The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water Research Education (2009)
- ISSN: 19367031
- DOI: 10.1111/j.1936-704X.2009.00061.x
Available from
Alexey Voinov's profile on Mendeley.
or
Available from
Alexey Voinov's profile on Mendeley.
Page 1
The Energy-Water Nexus: Why Should We Care?
17
UCOWRJournal of Contemporary Water researCh & eduCation
UNIVERSITIES COUNCIL ON WATER RESOURCES
J OURNAL OF CONTEMPORARY WATER RESEARCH & E DUCATION
I SSUE 143, P AGES 17-29, D ECEMBER 2009
The Energy-Water Nexus: Why Should We Care?
Alexey Voinov1,2 and Hal Cardwell1
1 institute for Water resources, us army Corps of engineers, fort Belvoir, Va;
2 Currently at international institute for Geo-information science and earth observation (itC), the netherlands
Water “will be to the 21st century what oil was to
the 20th.” (Fortune magazine 2000)
“That’s a big no. The president believes ... that it
should be the goal of policymakers to protect the
American way of life. The American way of life is
a blessed one.” (Ari Fleischer, White House Press
Secretary responding in May 2001 to whether
Bush would ask Americans to curb their first-in-
the-world energy consumption.)
Water and energy are essential for human livelihood and the large-scale capture and use of these resources have brought
many economic, social, and health benefits to
humans across the globe. Both energy and water
belong to the so-called critical natural capital
category, which means that they are essential for
human survival. As supply becomes scarce, they
exhibit high price inelasticity of demand, so that a
small reduction of supply leads to a huge increase
in price. As a result the total value (price x quantity)
rapidly increases as total quantity declines (Farley
and Gaddis 2007). This is true for any resource
that is essential and non-substitutable. As there is
less water or energy available, their price quickly
increases towards infinity. This can create havoc in
markets and stress the whole economic system, as
during the energy crisis of the 1970’s. Diminished
water supplies may lead to direct conflict and
violence. When energy and water supplies are
abundant, their value is low. It may seem that we
have an infinite supply and there is no need to
worry. However, as we approach depletion, even
small perturbations due to unforeseen climatic
events, sharp increases in demand or technical
malfunction results in disproportionate changes in
their values and prices, if the market is allowed to work.
Humans are quickly depleting non-renewable
fossil fuels to produce electricity, heat homes,
power vehicles and for other purposes. Likewise,
in many areas we are “depleting” (over utilizing
or degrading) our fresh water resources to the
extent that we must compensate for shortages by
either increasing energy use to import water from
other basins, desalinate salt water or reuse waste
water, or by depleting non-renewable water by
over-pumping water from fossil aquifers. These
practices are unsustainable and they may leave
future generations with fewer options and more
risks. Therefore, we will likely have to meet many
of our future water and energy needs via increased
efficiency and conservation.
Water and energy are intimately intertwined. For
example, in biofuel production water is essential for
growing, harvesting, and processing the biomass,
while additional energy is needed to allocate
and utilize water in the process (Figure 1). For a
comprehensive, valid assessment of these resources,
we need to conduct life cycle assessments that
track both the water and energy flows and storage
reservoirs for the entire system and estimate both
the inputs and outputs for each aspect of the system.
As water is required in production of almost all
forms of energy, energy is also essential for water
supply, treatment, desalinization, disposal, and
other uses. The water sector, including treatment
and conveyance, is presently one of the largest users
of energy, comparable to the paper and refining
industries (Anderson 1999). The demand for
energy in the water sector will likely substantially
outpace growth in other high-energy use sectors.
The most obvious use of water in the energy sector
is hydroelectric generation; however, the amount
of water withdrawn to generate thermal electric
power from fossil fuels is roughly equivalent to the
UCOWRJournal of Contemporary Water researCh & eduCation
UNIVERSITIES COUNCIL ON WATER RESOURCES
J OURNAL OF CONTEMPORARY WATER RESEARCH & E DUCATION
I SSUE 143, P AGES 17-29, D ECEMBER 2009
The Energy-Water Nexus: Why Should We Care?
Alexey Voinov1,2 and Hal Cardwell1
1 institute for Water resources, us army Corps of engineers, fort Belvoir, Va;
2 Currently at international institute for Geo-information science and earth observation (itC), the netherlands
Water “will be to the 21st century what oil was to
the 20th.” (Fortune magazine 2000)
“That’s a big no. The president believes ... that it
should be the goal of policymakers to protect the
American way of life. The American way of life is
a blessed one.” (Ari Fleischer, White House Press
Secretary responding in May 2001 to whether
Bush would ask Americans to curb their first-in-
the-world energy consumption.)
Water and energy are essential for human livelihood and the large-scale capture and use of these resources have brought
many economic, social, and health benefits to
humans across the globe. Both energy and water
belong to the so-called critical natural capital
category, which means that they are essential for
human survival. As supply becomes scarce, they
exhibit high price inelasticity of demand, so that a
small reduction of supply leads to a huge increase
in price. As a result the total value (price x quantity)
rapidly increases as total quantity declines (Farley
and Gaddis 2007). This is true for any resource
that is essential and non-substitutable. As there is
less water or energy available, their price quickly
increases towards infinity. This can create havoc in
markets and stress the whole economic system, as
during the energy crisis of the 1970’s. Diminished
water supplies may lead to direct conflict and
violence. When energy and water supplies are
abundant, their value is low. It may seem that we
have an infinite supply and there is no need to
worry. However, as we approach depletion, even
small perturbations due to unforeseen climatic
events, sharp increases in demand or technical
malfunction results in disproportionate changes in
their values and prices, if the market is allowed to work.
Humans are quickly depleting non-renewable
fossil fuels to produce electricity, heat homes,
power vehicles and for other purposes. Likewise,
in many areas we are “depleting” (over utilizing
or degrading) our fresh water resources to the
extent that we must compensate for shortages by
either increasing energy use to import water from
other basins, desalinate salt water or reuse waste
water, or by depleting non-renewable water by
over-pumping water from fossil aquifers. These
practices are unsustainable and they may leave
future generations with fewer options and more
risks. Therefore, we will likely have to meet many
of our future water and energy needs via increased
efficiency and conservation.
Water and energy are intimately intertwined. For
example, in biofuel production water is essential for
growing, harvesting, and processing the biomass,
while additional energy is needed to allocate
and utilize water in the process (Figure 1). For a
comprehensive, valid assessment of these resources,
we need to conduct life cycle assessments that
track both the water and energy flows and storage
reservoirs for the entire system and estimate both
the inputs and outputs for each aspect of the system.
As water is required in production of almost all
forms of energy, energy is also essential for water
supply, treatment, desalinization, disposal, and
other uses. The water sector, including treatment
and conveyance, is presently one of the largest users
of energy, comparable to the paper and refining
industries (Anderson 1999). The demand for
energy in the water sector will likely substantially
outpace growth in other high-energy use sectors.
The most obvious use of water in the energy sector
is hydroelectric generation; however, the amount
of water withdrawn to generate thermal electric
power from fossil fuels is roughly equivalent to the
Page 2
amount of water utilized by irrigated agriculture at
about 40 percent of U. S. withdrawals each (Hutson
et al. 2004).
For both energy and water, it is not just the
quantity that matters, but quality as well. For
water, quality is measured by the concentration of
impurities, constituents dissolved or suspended in
the water, as well as by its physical characteristics,
such as temperature. Water quality can be
significantly affected by energy-related projects.
For example, water used for cooling purposes
in power stations is returned to the river with a
higher temperature, which may prove detrimental
to some fisheries. Hydropower that requires dams
can also significantly affect physical and chemical
parameters of water. Mining may destroy whole
landscapes, including streams.
For energy, quality means efficiency, reliability,
and continuity of supply. We use one kind of energy
to produce other kinds of higher quality. Say, low
quality solar energy is abundant but hard to use.
In photosynthesis solar energy is accumulated in
woody biomass that can be then be used as a source
of energy of higher quality. With photovoltaics we
can convert solar energy directly into electricity,
which is of higher quality energy than biomass.
The efficiency can be measured utilizing the Energy
Return on Energy Invested index, discussed below.
If we need to use energy to produce a different type
of energy of the same quality, we lose efficiency.
The higher the quality, and the more efficient a
water or energy supply is, the more reliable and
the easier it is to provide to end users.
Water for Energy
As demand for water grows, there will be more
competition with regard to water needed for energy
production. If water becomes as limiting as energy,
there will be more pressure on water-intensive
energy producers to seek alternative supplies.
Energy Return on Water Invested is a useful
indicator to compare various methods of energy
generation. Ideally, it can be estimated for a given
technology by applying the life cycle assessment
methodology (International Standard Organization
2006, Guinée 2002) to calculate the energy
Figure 1. The life cycle of energy from biomass production.
Voinov and Cardwell18
Journal of Contemporary Water researCh & eduCationUCOWR
about 40 percent of U. S. withdrawals each (Hutson
et al. 2004).
For both energy and water, it is not just the
quantity that matters, but quality as well. For
water, quality is measured by the concentration of
impurities, constituents dissolved or suspended in
the water, as well as by its physical characteristics,
such as temperature. Water quality can be
significantly affected by energy-related projects.
For example, water used for cooling purposes
in power stations is returned to the river with a
higher temperature, which may prove detrimental
to some fisheries. Hydropower that requires dams
can also significantly affect physical and chemical
parameters of water. Mining may destroy whole
landscapes, including streams.
For energy, quality means efficiency, reliability,
and continuity of supply. We use one kind of energy
to produce other kinds of higher quality. Say, low
quality solar energy is abundant but hard to use.
In photosynthesis solar energy is accumulated in
woody biomass that can be then be used as a source
of energy of higher quality. With photovoltaics we
can convert solar energy directly into electricity,
which is of higher quality energy than biomass.
The efficiency can be measured utilizing the Energy
Return on Energy Invested index, discussed below.
If we need to use energy to produce a different type
of energy of the same quality, we lose efficiency.
The higher the quality, and the more efficient a
water or energy supply is, the more reliable and
the easier it is to provide to end users.
Water for Energy
As demand for water grows, there will be more
competition with regard to water needed for energy
production. If water becomes as limiting as energy,
there will be more pressure on water-intensive
energy producers to seek alternative supplies.
Energy Return on Water Invested is a useful
indicator to compare various methods of energy
generation. Ideally, it can be estimated for a given
technology by applying the life cycle assessment
methodology (International Standard Organization
2006, Guinée 2002) to calculate the energy
Figure 1. The life cycle of energy from biomass production.
Voinov and Cardwell18
Journal of Contemporary Water researCh & eduCationUCOWR
Page 3
produced per unit of fresh water used (megajoules/
liter, MJ/L or kcal/gal, 1 joule = 0.24 cal = 0.00028
watt/hour) for a given technology. Variations of
the life cycle assessment methodology are already
generally used to calculate the Energy Return on
Energy Invested for a technology (see Spreng 1988
for an overview) and the application of life cycle
assessment to estimate Energy Return on Water
Invested is analogous. However, things become
complicated since water does not necessarily have
to be consumed to produce energy. Much of the
water withdrawn for energy production is returned
back and can be reused. From a basin perspective,
the only consumption occurs when water is either
lost through evapotranspiration (in which case it
may also reappear in the basin, but at a different
place when rainfall occurs) or degraded through
contamination that changes its chemical properties
(e.g., toxic additions, including nutrients,
pesticides, herbicides) or physical properties (e.g.,
water temperature, oxygen content), to such an
extent that it is no longer usable.
Energy Return on Water Invested can be
calculated in a way similar to Energy Return on
Energy Invested. If, e
out
is the amount of energy
produced, and e
in
is the amount of energy used
in production, then, Energy Return on Energy
Invested, e = e
out
/ e
in
. In some cases net Energy
Return on Energy Invested is used, which is the
amount of energy we need to produce to deliver a
unit of net energy to the user:
e’ = e
out
/ (e
out
– e
in
). Or e’ = e / (e – 1).
Similarly Energy Return on Water Invested would
then be e
w
= e
out
/ w
in
, and net Energy Return on
Water Invested,
e
w
’ = (e
out
– e
in
)/w
in
= e
w
/ e’.
Energy Return on Energy Invested is usually
criticized for not taking into account all the other
resources (including social and environmental
ones) that are required to produce energy. One
could assume that as long as a technology has an e
> 1, it can then be chained as many times as needed
to produce infinite energy. This is certainly not the
case, because other resources may be depleted
along the chain (say, land, or pollution absorption
capacity, or certain metals or minerals that are
needed to run the operations). Therefore, Energy
Return on Energy Invested is a good indicator to
make comparisons between technologies (Cesar et
al. 2007); however, we must always keep in mind
the other limiting factors that can play a crucial role
(e.g., availability of land, environmental carrying
capacity, carbon dioxide and other greenhouse
gas emissions). Water is one such limiting factor,
so Energy Return on Water Invested is a good
supplement to Energy Return on Energy Invested,
taking into account the water needs for energy
production.
Mulder et al. (2007) estimate Energy Return on
Water Invested and net Energy Return on Water
Invested at various technologies showing that it can
range from 0.025 MJ/L for electricity production
from biomass up to 285.3 MJ/L for petroleum
diesel. Net Energy Return on Water Invested for
the same technologies was 0.02 and 228.4 MJ/L
respectively. The best net Energy Return on Water
Invested for biofuels (sugar cane ethanol) is 0.903,
over two orders of magnitude lower than the most
water-efficient fossil energy sources.
Indeed, the study by Kannan et al. (2004) for
a petroleum power plant in Singapore shows that
even electricity production, one of the least water-
efficient forms of fossil energy production, can
be made very water-efficient when necessary.
Singapore has perennial shortages of fresh water
and the petroleum power plant studied there has an
Energy Return on Water Invested seven times higher
than typical power plants with water recirculation.
This is because direct water withdrawals are
reduced to less than 0.02 L/MJ, a number dwarfed
by the lower-bound water withdrawals of 13 L/MJ
for biomass electricity production (Berndes 2002).
This implies that there are water-efficient fossil
electricity sources that yield almost 600 times as
much energy per unit of water invested, as does the
most water-efficient biomass source of electricity
reviewed by Berndes (2002).
Ethanol refining currently consumes 4-8 liters (1-
2 gal) and uses ~ 130 liters (34.34 gal) of water for
each liter of ethanol (Dominguez-Faus et al. 2009),
so we need 480 million to 4 billion m3 (127-1056
billion gal) of water to provide for the Presidents’
2025 goal of producing 120-240 billion liters (30-
60 billion gal) of ethanol. Some new technologies
used to convert cellulose to fuel use even more
water per liter of fuel gained than converting corn
to ethanol. Irrigating seed and field corn needed for
19
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
liter, MJ/L or kcal/gal, 1 joule = 0.24 cal = 0.00028
watt/hour) for a given technology. Variations of
the life cycle assessment methodology are already
generally used to calculate the Energy Return on
Energy Invested for a technology (see Spreng 1988
for an overview) and the application of life cycle
assessment to estimate Energy Return on Water
Invested is analogous. However, things become
complicated since water does not necessarily have
to be consumed to produce energy. Much of the
water withdrawn for energy production is returned
back and can be reused. From a basin perspective,
the only consumption occurs when water is either
lost through evapotranspiration (in which case it
may also reappear in the basin, but at a different
place when rainfall occurs) or degraded through
contamination that changes its chemical properties
(e.g., toxic additions, including nutrients,
pesticides, herbicides) or physical properties (e.g.,
water temperature, oxygen content), to such an
extent that it is no longer usable.
Energy Return on Water Invested can be
calculated in a way similar to Energy Return on
Energy Invested. If, e
out
is the amount of energy
produced, and e
in
is the amount of energy used
in production, then, Energy Return on Energy
Invested, e = e
out
/ e
in
. In some cases net Energy
Return on Energy Invested is used, which is the
amount of energy we need to produce to deliver a
unit of net energy to the user:
e’ = e
out
/ (e
out
– e
in
). Or e’ = e / (e – 1).
Similarly Energy Return on Water Invested would
then be e
w
= e
out
/ w
in
, and net Energy Return on
Water Invested,
e
w
’ = (e
out
– e
in
)/w
in
= e
w
/ e’.
Energy Return on Energy Invested is usually
criticized for not taking into account all the other
resources (including social and environmental
ones) that are required to produce energy. One
could assume that as long as a technology has an e
> 1, it can then be chained as many times as needed
to produce infinite energy. This is certainly not the
case, because other resources may be depleted
along the chain (say, land, or pollution absorption
capacity, or certain metals or minerals that are
needed to run the operations). Therefore, Energy
Return on Energy Invested is a good indicator to
make comparisons between technologies (Cesar et
al. 2007); however, we must always keep in mind
the other limiting factors that can play a crucial role
(e.g., availability of land, environmental carrying
capacity, carbon dioxide and other greenhouse
gas emissions). Water is one such limiting factor,
so Energy Return on Water Invested is a good
supplement to Energy Return on Energy Invested,
taking into account the water needs for energy
production.
Mulder et al. (2007) estimate Energy Return on
Water Invested and net Energy Return on Water
Invested at various technologies showing that it can
range from 0.025 MJ/L for electricity production
from biomass up to 285.3 MJ/L for petroleum
diesel. Net Energy Return on Water Invested for
the same technologies was 0.02 and 228.4 MJ/L
respectively. The best net Energy Return on Water
Invested for biofuels (sugar cane ethanol) is 0.903,
over two orders of magnitude lower than the most
water-efficient fossil energy sources.
Indeed, the study by Kannan et al. (2004) for
a petroleum power plant in Singapore shows that
even electricity production, one of the least water-
efficient forms of fossil energy production, can
be made very water-efficient when necessary.
Singapore has perennial shortages of fresh water
and the petroleum power plant studied there has an
Energy Return on Water Invested seven times higher
than typical power plants with water recirculation.
This is because direct water withdrawals are
reduced to less than 0.02 L/MJ, a number dwarfed
by the lower-bound water withdrawals of 13 L/MJ
for biomass electricity production (Berndes 2002).
This implies that there are water-efficient fossil
electricity sources that yield almost 600 times as
much energy per unit of water invested, as does the
most water-efficient biomass source of electricity
reviewed by Berndes (2002).
Ethanol refining currently consumes 4-8 liters (1-
2 gal) and uses ~ 130 liters (34.34 gal) of water for
each liter of ethanol (Dominguez-Faus et al. 2009),
so we need 480 million to 4 billion m3 (127-1056
billion gal) of water to provide for the Presidents’
2025 goal of producing 120-240 billion liters (30-
60 billion gal) of ethanol. Some new technologies
used to convert cellulose to fuel use even more
water per liter of fuel gained than converting corn
to ethanol. Irrigating seed and field corn needed for
19
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
Page 4
ethanol adds another 4 to 7 liters of water for each
liter of fuel (Mubako and Lant 2008). Irrigating
marginal land may need many times more water.
It should be also noted that various portions
of the production cycle have different water
requirements. For example, in biofuel production
irrigation requires orders of magnitude more
water than ethanol biorefineries (see Table 1).
However the intensity of water consumption can
be much higher for refineries, where thousands of
cubic meters of water are to be withdrawn on the
spot, significantly changing local hydrology and
requiring additional infrastructure to provide that
water.
Water required to produce one liter of Fischer-
Tropsch liquid product varies between 4.6 liters
to 6.8 liters (1.2-1.8 gal), depending on the coal
used for the process (160 to 250 liter per Mbtu
or 0.14-0.22 gal/kW-hour) (Marano and Ciferno
2001). For a 22,000 barrel-per-day operation, that
means 5-6 billion liters (1.32-1.58 billion gal) of
water per year, enough water to meet the domestic
needs of 26,000 people. According to estimates
from U. S. Department of Energy (DOE), more
than 4 liters of water are needed for every liter
of transportation fuel produced, threatening the
limited water supplies (DOE Report 2006:80).
China announced that it needs to curb coal-to-liquid
production, because of concerns over pollution
and the volumes of water consumed. Nevertheless
more recently it was announced that the facility
“will start operating later this year and is expected
to convert 3.5 million tons of coal per year into
one million tons of oil products such as diesel for
cars.” (Reuters 2008) They will use groundwater
and recycled water from coal mines to supply the 8
million tonnes it will need each year. In some parts
of China, 30 years ago the water table was 5 meters
below the ground. Today it is 35-40 meters below
the ground because the groundwater is used in an
unsustainable way.
Climate change will add to the synergies
between water and energy. Most of the water used
in energy production is used for cooling purposes,
and the greater the temperature differential the
more efficient the cooling process. This means that
there are strong requirements on the temperature of
water that is used. Therefore, as temperature at the
intake increases, there is a rising demand for water
to provide the same cooling effect with restrictions
on the outlet water temperature. Most plants have
regulations or other constraints that limit their
ability to adjust their withdrawal rates. In the short
run this means that they will get less cooling, a
corresponding decrease in turbine backpressure,
less efficient generation, and less electric energy
for the same amount of raw energy input. Also,
many nuclear plants have safety limits on intake
temperature that could trigger complete shutdowns
more frequently in altered climate scenarios. In
addition, environmental concerns usually impose
limitations on the temperature of water discharged
back into the streams and reservoirs.
As the cost of energy increases, demand will
grow for more energy-efficient technologies
and modes of operation. In particular, in the
energy-thirsty transportation sector, demand for
waterborne navigation throughout the country is
likely to increase, since waterborne transportation
is frequently low in energy and total costs. This
means more ships in rivers, canals, docks and ports.
Since this requires much new infrastructure, which
has high cost and long lead times, it is unlikely
that the system will react to short-term disruptions
in energy supply like those in the 1970s. But if
the energy shortage is severe and lasts over longer
Table 1. Estimated use of water for various technologies of biofuel production. (Aden et al. 2002, Phillips et al.
2007, Dutta and Phillips 2009).
Irrigation use Refinery use
Oil 0.5 – 1 liter water/liter gasoline
Corn 0 – 1909 l water/l ethanol 2 – 5 l water/l ethanol
Cellulose (Sorghum)
Sugar
Thermochemical
Carboxylate
0 – 398 l water/l ethanol
0 – 380 l water/l ethanol
0 – 277 l water/l ethanol
5.9 l water/l ethanol
1.65 l water/l ethanol
2.28 l water/l ethanol
Voinov and Cardwell20
Journal of Contemporary Water researCh & eduCationUCOWR
liter of fuel (Mubako and Lant 2008). Irrigating
marginal land may need many times more water.
It should be also noted that various portions
of the production cycle have different water
requirements. For example, in biofuel production
irrigation requires orders of magnitude more
water than ethanol biorefineries (see Table 1).
However the intensity of water consumption can
be much higher for refineries, where thousands of
cubic meters of water are to be withdrawn on the
spot, significantly changing local hydrology and
requiring additional infrastructure to provide that
water.
Water required to produce one liter of Fischer-
Tropsch liquid product varies between 4.6 liters
to 6.8 liters (1.2-1.8 gal), depending on the coal
used for the process (160 to 250 liter per Mbtu
or 0.14-0.22 gal/kW-hour) (Marano and Ciferno
2001). For a 22,000 barrel-per-day operation, that
means 5-6 billion liters (1.32-1.58 billion gal) of
water per year, enough water to meet the domestic
needs of 26,000 people. According to estimates
from U. S. Department of Energy (DOE), more
than 4 liters of water are needed for every liter
of transportation fuel produced, threatening the
limited water supplies (DOE Report 2006:80).
China announced that it needs to curb coal-to-liquid
production, because of concerns over pollution
and the volumes of water consumed. Nevertheless
more recently it was announced that the facility
“will start operating later this year and is expected
to convert 3.5 million tons of coal per year into
one million tons of oil products such as diesel for
cars.” (Reuters 2008) They will use groundwater
and recycled water from coal mines to supply the 8
million tonnes it will need each year. In some parts
of China, 30 years ago the water table was 5 meters
below the ground. Today it is 35-40 meters below
the ground because the groundwater is used in an
unsustainable way.
Climate change will add to the synergies
between water and energy. Most of the water used
in energy production is used for cooling purposes,
and the greater the temperature differential the
more efficient the cooling process. This means that
there are strong requirements on the temperature of
water that is used. Therefore, as temperature at the
intake increases, there is a rising demand for water
to provide the same cooling effect with restrictions
on the outlet water temperature. Most plants have
regulations or other constraints that limit their
ability to adjust their withdrawal rates. In the short
run this means that they will get less cooling, a
corresponding decrease in turbine backpressure,
less efficient generation, and less electric energy
for the same amount of raw energy input. Also,
many nuclear plants have safety limits on intake
temperature that could trigger complete shutdowns
more frequently in altered climate scenarios. In
addition, environmental concerns usually impose
limitations on the temperature of water discharged
back into the streams and reservoirs.
As the cost of energy increases, demand will
grow for more energy-efficient technologies
and modes of operation. In particular, in the
energy-thirsty transportation sector, demand for
waterborne navigation throughout the country is
likely to increase, since waterborne transportation
is frequently low in energy and total costs. This
means more ships in rivers, canals, docks and ports.
Since this requires much new infrastructure, which
has high cost and long lead times, it is unlikely
that the system will react to short-term disruptions
in energy supply like those in the 1970s. But if
the energy shortage is severe and lasts over longer
Table 1. Estimated use of water for various technologies of biofuel production. (Aden et al. 2002, Phillips et al.
2007, Dutta and Phillips 2009).
Irrigation use Refinery use
Oil 0.5 – 1 liter water/liter gasoline
Corn 0 – 1909 l water/l ethanol 2 – 5 l water/l ethanol
Cellulose (Sorghum)
Sugar
Thermochemical
Carboxylate
0 – 398 l water/l ethanol
0 – 380 l water/l ethanol
0 – 277 l water/l ethanol
5.9 l water/l ethanol
1.65 l water/l ethanol
2.28 l water/l ethanol
Voinov and Cardwell20
Journal of Contemporary Water researCh & eduCationUCOWR
Page 5
time, we will likely see more waterborne traffic,
and consequently, a higher rate of accidents
due to an increased number of ships, and more
impacts on the whole transportation system. In
particular, large amounts of coal are transported by
barges on waterways. As energy production and
overall economic performance depend more on
waterborne transportation, there will be even more
dependency upon smooth navigation. Navigation
disruptions because of drought or flooding could
have serious consequences that may propagate
through the whole economic system. As we will
see later, climate change can only exacerbate the
risks for the water-energy system.
Energy for Water
If there were unlimited energy, we would never
have a problem with obtaining water for use. For
example, there are vast resources of saline water
that could be desalinized to provide for all the
imaginable demands for water if there is energy
to run those operations and then pump water to
wherever it is needed. That is certainly not the
case. Energy is becoming an increasingly scarce
and, as a result, expensive commodity, and energy
efficiency is now a major concern. Water supply
in this case will need to compete with many other
energy uses, and the Water Return on Energy
Invested concept may become a useful measure to
compare various water supply projects.
Water Return on Energy Invested (w
e
= w
out
/ e
in
) can be calculated also in a way similar to
Energy Return on Energy Invested. Just like that
index, Water Return on Energy Invested does
not take into account any other resources besides
energy (including social and environmental ones)
that are required to produce water of the required
quality. So again when using Water Return on
Energy Invested to compare technologies, always
keep in mind the other limiting factors that can
spring into play: it is one of several indicators to
use in decision-making. There are many ways that
energy is required for production and distribution
of water.
Building and maintaining the infrastructure.
Water-related projects require huge capital and
energy investments. This includes energy for
building dams, canals, pipelines, irrigation, and
water disposal systems, including storm water
drainage.
Water purification and delivery. Energy is
needed to bring water to required quality standards
(drinking water) and for pumping water through
pipelines and canals, which is the main means for
water supply and distribution. This also includes
pumping for irrigation purposes, and pumping of
municipal and industrial waste water.
Waste water treatment. In addition to pumping,
this would include energy for aeration, stirring,
heating, and so forth (Table 2).
Direct transportation. Some water is moved
in trucks and trains. The $15 billon bottled
water industry is entirely dependent on energy
to manufacture, package, pump and haul bottled
water across huge distances. According to Fishman
(2007), “we are moving one billion bottles of
water around a week in ships, trains, and trucks in
the United States alone. That’s a weekly convoy
equivalent to 37,800 18-wheelers delivering water.”
Table 2. Current Average Unit Costs of Water (Shannon 2007). Assuming that most of the cost is for energy this can
give us an idea of relative energy consumption in different technologies.
Method Cost per 1000 m3 (263,000 gal)
Old Water $4-81, $40 average across U.S.
Reclamation non-potable $81-122 for industrial reuse
New conventional water $81-162 aquifer, direct draw (river, lake)
$243-405 for new developed water (dams, cannels, etc.)
Direct Reuse $348-405 for potable
Desalination (brackish) $405-486 for reduction from 8,000 ppm to 1,000 ppm
Desalination (seawater) $527 for next generation 200 million m3/yr plant Israel
$583 claimed in Tampa Bay (not achieved)
$648 actual current state-of-art RO costs
$770-1135 multistage flash distillation, depending on salinity and local energy costs
21
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
and consequently, a higher rate of accidents
due to an increased number of ships, and more
impacts on the whole transportation system. In
particular, large amounts of coal are transported by
barges on waterways. As energy production and
overall economic performance depend more on
waterborne transportation, there will be even more
dependency upon smooth navigation. Navigation
disruptions because of drought or flooding could
have serious consequences that may propagate
through the whole economic system. As we will
see later, climate change can only exacerbate the
risks for the water-energy system.
Energy for Water
If there were unlimited energy, we would never
have a problem with obtaining water for use. For
example, there are vast resources of saline water
that could be desalinized to provide for all the
imaginable demands for water if there is energy
to run those operations and then pump water to
wherever it is needed. That is certainly not the
case. Energy is becoming an increasingly scarce
and, as a result, expensive commodity, and energy
efficiency is now a major concern. Water supply
in this case will need to compete with many other
energy uses, and the Water Return on Energy
Invested concept may become a useful measure to
compare various water supply projects.
Water Return on Energy Invested (w
e
= w
out
/ e
in
) can be calculated also in a way similar to
Energy Return on Energy Invested. Just like that
index, Water Return on Energy Invested does
not take into account any other resources besides
energy (including social and environmental ones)
that are required to produce water of the required
quality. So again when using Water Return on
Energy Invested to compare technologies, always
keep in mind the other limiting factors that can
spring into play: it is one of several indicators to
use in decision-making. There are many ways that
energy is required for production and distribution
of water.
Building and maintaining the infrastructure.
Water-related projects require huge capital and
energy investments. This includes energy for
building dams, canals, pipelines, irrigation, and
water disposal systems, including storm water
drainage.
Water purification and delivery. Energy is
needed to bring water to required quality standards
(drinking water) and for pumping water through
pipelines and canals, which is the main means for
water supply and distribution. This also includes
pumping for irrigation purposes, and pumping of
municipal and industrial waste water.
Waste water treatment. In addition to pumping,
this would include energy for aeration, stirring,
heating, and so forth (Table 2).
Direct transportation. Some water is moved
in trucks and trains. The $15 billon bottled
water industry is entirely dependent on energy
to manufacture, package, pump and haul bottled
water across huge distances. According to Fishman
(2007), “we are moving one billion bottles of
water around a week in ships, trains, and trucks in
the United States alone. That’s a weekly convoy
equivalent to 37,800 18-wheelers delivering water.”
Table 2. Current Average Unit Costs of Water (Shannon 2007). Assuming that most of the cost is for energy this can
give us an idea of relative energy consumption in different technologies.
Method Cost per 1000 m3 (263,000 gal)
Old Water $4-81, $40 average across U.S.
Reclamation non-potable $81-122 for industrial reuse
New conventional water $81-162 aquifer, direct draw (river, lake)
$243-405 for new developed water (dams, cannels, etc.)
Direct Reuse $348-405 for potable
Desalination (brackish) $405-486 for reduction from 8,000 ppm to 1,000 ppm
Desalination (seawater) $527 for next generation 200 million m3/yr plant Israel
$583 claimed in Tampa Bay (not achieved)
$648 actual current state-of-art RO costs
$770-1135 multistage flash distillation, depending on salinity and local energy costs
21
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
Page 6
Desalinization. The minimum amount of energy
reported for seawater (34,000 ppm) desalinization
is 0.79 W-hr/liter (3 W-hr/gal). An indirect way
to identify Water Return on Energy Invested is to
look at the dollar cost of delivering water from
various sources. Table 3 lists some of the costs of
water at current prices. It also gives an idea of what
the relative costs of different technologies are.
Direct coupling of renewable energy generation to
desalinization facilities (e.g. wind-powered desal)
is a promising way to further increase efficiency.
Supply Side
So far most of the solutions for energy and
water shortages are sought on the supply side.
The traditional approach is to forecast the growth
trends for demand, and then seek resources
– either through new and improved conservation
or efficiency technologies, or through capturing
new local resources (e.g. developing new ground
water resources, or new oil fields), or importing
water or fuel from elsewhere. In most cases, the
Federal agencies are charged to provide the supply
necessary to meet existing or future demands.
For example, the U.S. Department of Energy is
responsible to “promote a diverse supply … of
reliable, affordable and environmentally sound
energy.” The U.S. Army Corps of Engineers and
U.S. Bureau of Reclamation are similarly directed
to provide water. Most of the Federal and state
efforts are focused on increasing the supply. For
example, in Nevada, the Southern Nevada Water
Voinov and Cardwell
Journal of Contemporary Water researCh & eduCationUCOWR
22
Table 3. Water Return on Energy Invested for some selected technologies of water production, recovery and application.
Reverse Osmosis
(Shannon 2007a)
50% water recovery
min Elec. 1.77 W•hr/liter
best Elec. 2.22 W•hr/liter
80% water recovery
min Elec. 5 W•hr/liter
best Elec. 8.40 W•hr/liter
Total annual energy for typical 3,785 m3/d (1 Mgal/d) wastewater treatment system (electrical plus fuel, expressed
as 1,000 kwh/yr) (Middlebrooks, 1979).
Treatment System
Efficient Quality, mg/L
Energy,
1,000
kwh/yr
Bio-
chemical
Oxygen
Demand
Suspended
Solid
Phosphorus Nitrogen
Rapid infiltration (facultative pond) 5 1 2 10 150
Slow rate, ridge + furrow (facultative pond) 2 1 0.1 3 181
Overland flow (facultative pond) 5 5 5 3 226
Facultative pond + intermittent filter 15 15 -- 10 241
Facultative pond + microscreens 30 30 -- 15 281
Aerated pond + intermittent filter 15 15 -- 20 506
Extended aeration + sludge drying 20 20 -- -- 683
Extended aeration + intermittent filter 15 15 -- -- 708
Trickling filter + anaerobic digestion 30 30 -- -- 783
Rotating biological contactor + anaerobic digestion 30 30 -- -- 794
Trickling filter + gravity filtration 20 10 -- -- 805
Trickling filter + N removal filter 20 10 -- 5 838
Activated sludge + anaerobic digestion 20 20 -- -- 889
Activated sludge + anaerobic digestion + filter 15 20 -- -- 911
Activated sludge + nitrification + filter 15 20 -- -- 1,051
Activated sludge + sludge incineration 20 20 -- -- 1,440
Activated sludge + AWT <10 5 <1 <1 3,809
Physical chemical advanced secondary 10 10 1 -- 4,464
reported for seawater (34,000 ppm) desalinization
is 0.79 W-hr/liter (3 W-hr/gal). An indirect way
to identify Water Return on Energy Invested is to
look at the dollar cost of delivering water from
various sources. Table 3 lists some of the costs of
water at current prices. It also gives an idea of what
the relative costs of different technologies are.
Direct coupling of renewable energy generation to
desalinization facilities (e.g. wind-powered desal)
is a promising way to further increase efficiency.
Supply Side
So far most of the solutions for energy and
water shortages are sought on the supply side.
The traditional approach is to forecast the growth
trends for demand, and then seek resources
– either through new and improved conservation
or efficiency technologies, or through capturing
new local resources (e.g. developing new ground
water resources, or new oil fields), or importing
water or fuel from elsewhere. In most cases, the
Federal agencies are charged to provide the supply
necessary to meet existing or future demands.
For example, the U.S. Department of Energy is
responsible to “promote a diverse supply … of
reliable, affordable and environmentally sound
energy.” The U.S. Army Corps of Engineers and
U.S. Bureau of Reclamation are similarly directed
to provide water. Most of the Federal and state
efforts are focused on increasing the supply. For
example, in Nevada, the Southern Nevada Water
Voinov and Cardwell
Journal of Contemporary Water researCh & eduCationUCOWR
22
Table 3. Water Return on Energy Invested for some selected technologies of water production, recovery and application.
Reverse Osmosis
(Shannon 2007a)
50% water recovery
min Elec. 1.77 W•hr/liter
best Elec. 2.22 W•hr/liter
80% water recovery
min Elec. 5 W•hr/liter
best Elec. 8.40 W•hr/liter
Total annual energy for typical 3,785 m3/d (1 Mgal/d) wastewater treatment system (electrical plus fuel, expressed
as 1,000 kwh/yr) (Middlebrooks, 1979).
Treatment System
Efficient Quality, mg/L
Energy,
1,000
kwh/yr
Bio-
chemical
Oxygen
Demand
Suspended
Solid
Phosphorus Nitrogen
Rapid infiltration (facultative pond) 5 1 2 10 150
Slow rate, ridge + furrow (facultative pond) 2 1 0.1 3 181
Overland flow (facultative pond) 5 5 5 3 226
Facultative pond + intermittent filter 15 15 -- 10 241
Facultative pond + microscreens 30 30 -- 15 281
Aerated pond + intermittent filter 15 15 -- 20 506
Extended aeration + sludge drying 20 20 -- -- 683
Extended aeration + intermittent filter 15 15 -- -- 708
Trickling filter + anaerobic digestion 30 30 -- -- 783
Rotating biological contactor + anaerobic digestion 30 30 -- -- 794
Trickling filter + gravity filtration 20 10 -- -- 805
Trickling filter + N removal filter 20 10 -- 5 838
Activated sludge + anaerobic digestion 20 20 -- -- 889
Activated sludge + anaerobic digestion + filter 15 20 -- -- 911
Activated sludge + nitrification + filter 15 20 -- -- 1,051
Activated sludge + sludge incineration 20 20 -- -- 1,440
Activated sludge + AWT <10 5 <1 <1 3,809
Physical chemical advanced secondary 10 10 1 -- 4,464
Page 7
Authority states: “One of the main objectives of
the Authority is to obtain additional water from
Colorado River to support urban growth of its
member agencies.” (Dziegielewski and Kiefer
2006:10). The Report of the Western Water Policy
Review Advisory Commission (1998) lists 12
Federal agencies with their responsibilities as
related to water (Fort 1998). Hardly any of them
have direct responsibility to reduce demand. At the
same time, problems with energy and water supply
are looming. There are two major factors that may
have a very negative impact on the supply side:
climate change and peak oil.
Climate change will affect supply of both energy
and water. It is hard to predict the exact extent and
rate of the impact, but the direction is quite clear
and we should certainly make provisions and adapt
to the forthcoming changes (Table 4).
Global warming could increase the cost of
natural disasters so quickly that one of the world’s
largest reinsurance firms, Swiss RE, warns that
climate change could all by itself bankrupt the
world economy before 20601 (Greer 2004). It
can significantly increase risk along many supply
chains. According to findings of the Military
Advisory Board (CNA 2007), “climate change acts
as a threat multiplier for instability in some of the
most volatile regions of the world.” Also it “will
add to tensions even in stable regions of the world.”
Besides, adaptation to climate change will require
more infrastructure, more new construction, which
means more energy and, perhaps, water to spend.
Peak Oil is the term used to describe the future
of fossil fuel production characterized by reduced
Figure 2. The pattern of oil extraction according to M. King Hubbert and his projections for peak oil (Hubbert
1974).
23
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
Table 4. Water-related changes associated with climate change and their impacts on energy and water.
Changes Effects
Melting glaciers and snow-packs Loss of long-term storage of water, lower baseflow, unreliable water
supply, more floods and droughts
Intrusion of saline water due to sea-
water rise
Problems with drinking water, need for treatment of brackish water
Changed patterns of precipitation
(“That ‘Drought’ in Southwest may
be normal, report says”)
Changes in spatial patterns of rainfall, loss of wetlands in certain places,
occurrence in others. Migration of habitat. Changed hydroperiod, impacts
of hydroelectric production
Increased frequency of “natural”
disasters
Changes in temporal patterns, hurricanes, floods and droughts, damage and
loss of infrastructure. Higher risk and insurance costs
Heat waves Higher temperatures, higher evapotranspiration, more losses from reser-
voirs, problems with cooling for nuclear and fossil electric
the Authority is to obtain additional water from
Colorado River to support urban growth of its
member agencies.” (Dziegielewski and Kiefer
2006:10). The Report of the Western Water Policy
Review Advisory Commission (1998) lists 12
Federal agencies with their responsibilities as
related to water (Fort 1998). Hardly any of them
have direct responsibility to reduce demand. At the
same time, problems with energy and water supply
are looming. There are two major factors that may
have a very negative impact on the supply side:
climate change and peak oil.
Climate change will affect supply of both energy
and water. It is hard to predict the exact extent and
rate of the impact, but the direction is quite clear
and we should certainly make provisions and adapt
to the forthcoming changes (Table 4).
Global warming could increase the cost of
natural disasters so quickly that one of the world’s
largest reinsurance firms, Swiss RE, warns that
climate change could all by itself bankrupt the
world economy before 20601 (Greer 2004). It
can significantly increase risk along many supply
chains. According to findings of the Military
Advisory Board (CNA 2007), “climate change acts
as a threat multiplier for instability in some of the
most volatile regions of the world.” Also it “will
add to tensions even in stable regions of the world.”
Besides, adaptation to climate change will require
more infrastructure, more new construction, which
means more energy and, perhaps, water to spend.
Peak Oil is the term used to describe the future
of fossil fuel production characterized by reduced
Figure 2. The pattern of oil extraction according to M. King Hubbert and his projections for peak oil (Hubbert
1974).
23
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
Table 4. Water-related changes associated with climate change and their impacts on energy and water.
Changes Effects
Melting glaciers and snow-packs Loss of long-term storage of water, lower baseflow, unreliable water
supply, more floods and droughts
Intrusion of saline water due to sea-
water rise
Problems with drinking water, need for treatment of brackish water
Changed patterns of precipitation
(“That ‘Drought’ in Southwest may
be normal, report says”)
Changes in spatial patterns of rainfall, loss of wetlands in certain places,
occurrence in others. Migration of habitat. Changed hydroperiod, impacts
of hydroelectric production
Increased frequency of “natural”
disasters
Changes in temporal patterns, hurricanes, floods and droughts, damage and
loss of infrastructure. Higher risk and insurance costs
Heat waves Higher temperatures, higher evapotranspiration, more losses from reser-
voirs, problems with cooling for nuclear and fossil electric
Page 8
discoveries, declining production, increasing
demand, politically sensitive reserves, “resource
nationalism,” and vulnerable infrastructure. The
“Hubbert Curve,” devised by geologist M. King
Hubbert in 1956, reflects production over time for
any oil reserve from a single oil well to a planet. It
is a bell shaped curve that describes how oil comes
slowly at first, rises to peak production, then falls
gradually to near zero (Hubbert 1974). The peak
arrives when roughly half the oil is gone (Figure 2).
Hubbert correctly predicted that oil production in
the continental U.S. would peak in approximately
1970 and production has slumped ever since. Many
energy scientists estimate that the worldwide peak
will occur before 2010. After the peak, according
to the Hubbert Curve, global oil production will
decline at about the same rate as it rose before.
With a peak before 2010, production in 2030 will
be somewhere around production in 1975 or 1980,
or maybe 20 billion barrels. However, by 2030
that oil production will have to meet the needs of
a doubled world population. Even if oil production
does not physically peak when anticipated, world
oil demand is outpacing our ability to supply
sufficient quantities of oil (as well as coal and
natural gas). Certainly, there will always be some
fossil fuels remaining in the ground; however, their
extraction will become increasingly expensive to
the point where it will make little sense to extract
them (this includes some alternative sources such
as tar sands, deep off-shore drilling, etc.). The
rapidly increasing costs may severely harm many
of the world’s economies – something we already
see with the current crisis.
Very similarly to oil reserves, we have the
luxury of fossil water – huge reserves of water,
sometimes of very high quality, accumulated
over many thousands of years and securely stored
underground. However, in many areas of the
world we are quickly depleting those reserves to
supplement over-allocated surface water supplies.
The U.S. Department of Agriculture reports that
in parts of Texas, Oklahoma, and Kansas – three
leading grain-producing states – the water table
for the Ogallala aquifer has dropped by more than
30 meters (100 feet). As a result, many wells have
gone dry on thousands of farms in the southern
Great Plains (Brown 2006).
Decreased production due to the peak oil factor is
likely to play a strong destabilizing effect on world
economy and energy markets, which may likely
result in calls for lower environmental standards,
deregulation and further privatization. There is a
growing sense of urgency because both water and
energy-related projects require significant time and
investments and cannot be implemented as a last
minute fix during emergencies.
Demand Side
It is getting increasingly clear that humanity can
survive only by living within the limits of physically
and economically available resources. In this
context, fossil fuels appear analogous to winning a
lottery ticket, or inheriting a fortune, which indeed
is exactly what it is. It is a huge energy reserve that
developed over eons without any cost to or input
by humans, that we can now utilize to our benefit
for the cost of extraction. Without that reserve,
we have only the steady supply of energy coming
from the sun, the water that comes from rainfall,
and whatever other resources we can recycle.
The windfall of fossil energy was our chance to
learn how to harness more of the solar energy
that comes to Earth and can be captured either
directly (photovoltaics) or indirectly (from wind,
bioenergy), or from non-solar sources (e.g., tidal,
geothermal). Whatever we learn and whatever
technologies we build while we still have access to
relatively cheap fossil fuels is what we will be left
with in the long years ahead after we run out of the
fossil reserve. Note that inventing technologies is
not enough: we will need energy, and much of it, to
develop the newly-invented infrastructure.
However, so far demand is treated as a given; it is
rarely managed or controlled, and it drives supply.
The U.S. has the third highest per capita domestic
water consumption – 217 m3/cap/yr (after Australia
– 341 m3/cap/yr and Canada – 279 m3/cap/yr). To
compare, in China it is 26 m3/cap/yr. This indicator
does not correlate with economic development: for
example in highly developed European countries
like Germany or the Netherlands the domestic
water consumption is quite low – 66 and 28 m3/
cap/yr, respectively (Chapagain and Hoekstra
2004). These figures are hard to compare directly,
since they may not account for climatic conditions
or what the actual uses are (e.g., there is little lawn
irrigation needed in the Netherlands). However,
Voinov and Cardwell24
Journal of Contemporary Water researCh & eduCationUCOWR
demand, politically sensitive reserves, “resource
nationalism,” and vulnerable infrastructure. The
“Hubbert Curve,” devised by geologist M. King
Hubbert in 1956, reflects production over time for
any oil reserve from a single oil well to a planet. It
is a bell shaped curve that describes how oil comes
slowly at first, rises to peak production, then falls
gradually to near zero (Hubbert 1974). The peak
arrives when roughly half the oil is gone (Figure 2).
Hubbert correctly predicted that oil production in
the continental U.S. would peak in approximately
1970 and production has slumped ever since. Many
energy scientists estimate that the worldwide peak
will occur before 2010. After the peak, according
to the Hubbert Curve, global oil production will
decline at about the same rate as it rose before.
With a peak before 2010, production in 2030 will
be somewhere around production in 1975 or 1980,
or maybe 20 billion barrels. However, by 2030
that oil production will have to meet the needs of
a doubled world population. Even if oil production
does not physically peak when anticipated, world
oil demand is outpacing our ability to supply
sufficient quantities of oil (as well as coal and
natural gas). Certainly, there will always be some
fossil fuels remaining in the ground; however, their
extraction will become increasingly expensive to
the point where it will make little sense to extract
them (this includes some alternative sources such
as tar sands, deep off-shore drilling, etc.). The
rapidly increasing costs may severely harm many
of the world’s economies – something we already
see with the current crisis.
Very similarly to oil reserves, we have the
luxury of fossil water – huge reserves of water,
sometimes of very high quality, accumulated
over many thousands of years and securely stored
underground. However, in many areas of the
world we are quickly depleting those reserves to
supplement over-allocated surface water supplies.
The U.S. Department of Agriculture reports that
in parts of Texas, Oklahoma, and Kansas – three
leading grain-producing states – the water table
for the Ogallala aquifer has dropped by more than
30 meters (100 feet). As a result, many wells have
gone dry on thousands of farms in the southern
Great Plains (Brown 2006).
Decreased production due to the peak oil factor is
likely to play a strong destabilizing effect on world
economy and energy markets, which may likely
result in calls for lower environmental standards,
deregulation and further privatization. There is a
growing sense of urgency because both water and
energy-related projects require significant time and
investments and cannot be implemented as a last
minute fix during emergencies.
Demand Side
It is getting increasingly clear that humanity can
survive only by living within the limits of physically
and economically available resources. In this
context, fossil fuels appear analogous to winning a
lottery ticket, or inheriting a fortune, which indeed
is exactly what it is. It is a huge energy reserve that
developed over eons without any cost to or input
by humans, that we can now utilize to our benefit
for the cost of extraction. Without that reserve,
we have only the steady supply of energy coming
from the sun, the water that comes from rainfall,
and whatever other resources we can recycle.
The windfall of fossil energy was our chance to
learn how to harness more of the solar energy
that comes to Earth and can be captured either
directly (photovoltaics) or indirectly (from wind,
bioenergy), or from non-solar sources (e.g., tidal,
geothermal). Whatever we learn and whatever
technologies we build while we still have access to
relatively cheap fossil fuels is what we will be left
with in the long years ahead after we run out of the
fossil reserve. Note that inventing technologies is
not enough: we will need energy, and much of it, to
develop the newly-invented infrastructure.
However, so far demand is treated as a given; it is
rarely managed or controlled, and it drives supply.
The U.S. has the third highest per capita domestic
water consumption – 217 m3/cap/yr (after Australia
– 341 m3/cap/yr and Canada – 279 m3/cap/yr). To
compare, in China it is 26 m3/cap/yr. This indicator
does not correlate with economic development: for
example in highly developed European countries
like Germany or the Netherlands the domestic
water consumption is quite low – 66 and 28 m3/
cap/yr, respectively (Chapagain and Hoekstra
2004). These figures are hard to compare directly,
since they may not account for climatic conditions
or what the actual uses are (e.g., there is little lawn
irrigation needed in the Netherlands). However,
Voinov and Cardwell24
Journal of Contemporary Water researCh & eduCationUCOWR
Page 9
they certainly reflect some of the patterns in
consumption, driven by relatively high water
prices and the culture of low domestic use that
is dominant in most European countries but still
quite foreign in the U.S. U.S. agricultural water
consumption is also increased by the high protein
meat diets that we choose.
The same trends apply to energy consumption,
as well as consumption of other goods and
services: with 4.6 percent of world population (US
Census, 2009), the U.S. produces 14.9 percent
and consumes 22.5 percent of world energy (EIA,
2009). Hall (1994) estimated that in terms of
resource consumption, every human born in the
U.S. is equivalent to 200 people born in Bangladesh.
It does not matter whether our population grows
because of high birth rates or because of high
immigration. In either case, because of our very
high consumption rates, every person in the U.S.
comes with a very high price tag for the resources
of this planet. Demand growth has a positive
feedback that magnifies itself. Additional goods
and services provided to meet new demands
require additional infrastructure and maintenance
that further increase demand. Every additional car
put on the street requires more roads, more repair
shops, more gasoline, more traffic control, etc. It
is a vicious circle that becomes almost impossible
to break if we stay within the standard “business as
usual” paradigm.
Human actions have no doubt been motivated
by efforts to survive and flourish, and one way to
read the earth’s history is to see it as the story of
the rise to primacy in the animal world of Homo
sapiens. The problem has been that, in this rise to
the top, human actions have had the consequence
of undermining the “conditions of production” in
ways that may ultimately sap the ability of humans
and others to survive on this planet (Wallerstein
2003). Curbing demand is cheaper, faster, and
ultimately more beneficial to individuals than
increasing supply. Conservation of energy saves
both energy and water. Optimal water use saves
both water and energy. More and more people
are realizing this and a few governments in the
U.S. and around the world have begun to respond
through energy-saver regulations, voluntary, and
domestic energy efficiency programs. But, as
public awareness and costs of our high use rates
increase (as they naturally will), the focus will
likely shift from solely the technical, engineering
arena to the socio-psychological domain. From
the growth paradigm, which is central to most
of the policies of today, we will have to move to
alternative sustainable approaches.
Thus far, government programs and private
sector advertising are focused on increasing
demand and production rather than decreasing
them. However, the same tools can be used to
promote the goals of conservation and lower
use. There are examples in the past, when public
perception was driven towards a common goal in
such a way that, for instance, during World War II it
was considered to be patriotic to purchase Treasury
Saving Bonds, in this way removing excess money
from the consumer market and saving it for a good
purpose. Similarly, at that time, very extensive
recycling programs, for example for tires and
metal, were put in place, and it was unpatriotic to
waste or not to recycle. It should be possible to
devise incentives to reduce demand for goods and
services and thereby reduce demand for energy
and water. With the current energy crisis, it would
make perfect sense to consider wasteful energy use
(i.e., driving big SUVs and trucks) to be unpatriotic
and support terrorism. Unfortunately, so far,
developing and selling energy and water is viewed
as a means to generate profit, benefiting the private
sector, and generating tax revenues. Consequently,
conservation “only” saves individuals money - it
does not “churn on the economy.”
There is a clear correlation between energy
consumption and economic development.
However, there is no obvious correlation between
gross domestic product and such “quality of life”
indicators as “life satisfaction,” or life expectancy.
With no sacrifice to life quality we can at least
halve the per capita gross domestic product and
therefore reduce energy consumption accordingly.
(Figure 3) It is really a matter of choice, social
attractiveness and cultural priorities, which can be
changed only with a strong leadership that should
be advanced and promoted by the Federal (and
other world) government(s).
Decreasing consumption may be an
unpopular measure, but that makes Federal
involvement especially important. So far most
of the advertisement industry is working towards
25
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
consumption, driven by relatively high water
prices and the culture of low domestic use that
is dominant in most European countries but still
quite foreign in the U.S. U.S. agricultural water
consumption is also increased by the high protein
meat diets that we choose.
The same trends apply to energy consumption,
as well as consumption of other goods and
services: with 4.6 percent of world population (US
Census, 2009), the U.S. produces 14.9 percent
and consumes 22.5 percent of world energy (EIA,
2009). Hall (1994) estimated that in terms of
resource consumption, every human born in the
U.S. is equivalent to 200 people born in Bangladesh.
It does not matter whether our population grows
because of high birth rates or because of high
immigration. In either case, because of our very
high consumption rates, every person in the U.S.
comes with a very high price tag for the resources
of this planet. Demand growth has a positive
feedback that magnifies itself. Additional goods
and services provided to meet new demands
require additional infrastructure and maintenance
that further increase demand. Every additional car
put on the street requires more roads, more repair
shops, more gasoline, more traffic control, etc. It
is a vicious circle that becomes almost impossible
to break if we stay within the standard “business as
usual” paradigm.
Human actions have no doubt been motivated
by efforts to survive and flourish, and one way to
read the earth’s history is to see it as the story of
the rise to primacy in the animal world of Homo
sapiens. The problem has been that, in this rise to
the top, human actions have had the consequence
of undermining the “conditions of production” in
ways that may ultimately sap the ability of humans
and others to survive on this planet (Wallerstein
2003). Curbing demand is cheaper, faster, and
ultimately more beneficial to individuals than
increasing supply. Conservation of energy saves
both energy and water. Optimal water use saves
both water and energy. More and more people
are realizing this and a few governments in the
U.S. and around the world have begun to respond
through energy-saver regulations, voluntary, and
domestic energy efficiency programs. But, as
public awareness and costs of our high use rates
increase (as they naturally will), the focus will
likely shift from solely the technical, engineering
arena to the socio-psychological domain. From
the growth paradigm, which is central to most
of the policies of today, we will have to move to
alternative sustainable approaches.
Thus far, government programs and private
sector advertising are focused on increasing
demand and production rather than decreasing
them. However, the same tools can be used to
promote the goals of conservation and lower
use. There are examples in the past, when public
perception was driven towards a common goal in
such a way that, for instance, during World War II it
was considered to be patriotic to purchase Treasury
Saving Bonds, in this way removing excess money
from the consumer market and saving it for a good
purpose. Similarly, at that time, very extensive
recycling programs, for example for tires and
metal, were put in place, and it was unpatriotic to
waste or not to recycle. It should be possible to
devise incentives to reduce demand for goods and
services and thereby reduce demand for energy
and water. With the current energy crisis, it would
make perfect sense to consider wasteful energy use
(i.e., driving big SUVs and trucks) to be unpatriotic
and support terrorism. Unfortunately, so far,
developing and selling energy and water is viewed
as a means to generate profit, benefiting the private
sector, and generating tax revenues. Consequently,
conservation “only” saves individuals money - it
does not “churn on the economy.”
There is a clear correlation between energy
consumption and economic development.
However, there is no obvious correlation between
gross domestic product and such “quality of life”
indicators as “life satisfaction,” or life expectancy.
With no sacrifice to life quality we can at least
halve the per capita gross domestic product and
therefore reduce energy consumption accordingly.
(Figure 3) It is really a matter of choice, social
attractiveness and cultural priorities, which can be
changed only with a strong leadership that should
be advanced and promoted by the Federal (and
other world) government(s).
Decreasing consumption may be an
unpopular measure, but that makes Federal
involvement especially important. So far most
of the advertisement industry is working towards
25
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
Page 10
increasing consumption, which directly translates
into using more energy and water. Federal action
can address that and help shift awareness of the
population towards conservation and efficiency.
There is an urgent need for a paradigm shift from
promoting growth to sustainability. Sustainable
growth is impossible on a finite planet; we can
only talk about sustainable development. That is
because it is unlikely that supply will be able to
forever respond to demand increases assuming
finite planetary resources. There are clear limits
to supply whereas demand is unlimited. It would
make more sense to manage demand and to make
it dependent upon the supply that is available
on a sustainable basis. This also applies to the
spatial distribution of resources: we should
develop demand in those places where we have
supply, and to the level that it can be sustained.
Ironically, in many cases we now have exactly the
reverse: nationally population is growing most
rapidly where water is least available. Conveying
energy creates large energy losses. Conveying
water requires much energy and also results in
significant losses of water due to evaporation and
seepage. Demand tends to feed upon itself. In this
case growing demand in areas where the supply is
limited is even further magnified by transportation
costs.
Conclusion
There are several factors that only increase the
complexity of the human-dominated system on
planet Earth. We no longer deal with dispersed
oases of civilization that barely affect each other.
We have created a global system that is closely
coupled and crises in one location send waves
of disruption throughout the system. The fact
that we live in a globalized system creates new
opportunities, but also increases our risks, since
there may be no refugia in case of a collapse. It will
be unlikely that one developed country or region
will be able to maintain its high quality of life if the
rest of the world will be in substantial crisis. We
have become very interdependent worldwide.
At the same time, as humans exert increasing
levels of impact upon the Earth’s life support system,
they are creating increasingly complex systems
of governance. The democratic decision support
system is robust and resilient, and it maintains itself
very well. However, it is not efficient in times of
crisis, when fast decisions and actions are required.
The checks and balances, which are essential for
the maintenance of the democracies, slow down the
change that may be needed for a fast response. As
the complexity of the governance system increases,
it becomes harder to expect average voters to have
the level of education and knowledge needed to
make the right decisions or the initiative to stay
involved. It becomes even more natural to delegate
the decision making to elected officials who know
what they are doing. At the same time, that may
erode the democratic process, as the knowledge gap
between well-informed officials and the general
electorate grows. This degrades the democracy and
requires further checks and balances that impede
decision-making.
The democratic process draws from market-
Figure 3. Relationship between gross domestic product per capita and life quality indices calculated for 97
countries.
Voinov and Cardwell26
Journal of Contemporary Water researCh & eduCationUCOWR
L
if
e
ex
pe
ct
an
cy
(
ye
ar
s)
L
if
e
sa
ti
sf
ac
ti
on
in
de
x
into using more energy and water. Federal action
can address that and help shift awareness of the
population towards conservation and efficiency.
There is an urgent need for a paradigm shift from
promoting growth to sustainability. Sustainable
growth is impossible on a finite planet; we can
only talk about sustainable development. That is
because it is unlikely that supply will be able to
forever respond to demand increases assuming
finite planetary resources. There are clear limits
to supply whereas demand is unlimited. It would
make more sense to manage demand and to make
it dependent upon the supply that is available
on a sustainable basis. This also applies to the
spatial distribution of resources: we should
develop demand in those places where we have
supply, and to the level that it can be sustained.
Ironically, in many cases we now have exactly the
reverse: nationally population is growing most
rapidly where water is least available. Conveying
energy creates large energy losses. Conveying
water requires much energy and also results in
significant losses of water due to evaporation and
seepage. Demand tends to feed upon itself. In this
case growing demand in areas where the supply is
limited is even further magnified by transportation
costs.
Conclusion
There are several factors that only increase the
complexity of the human-dominated system on
planet Earth. We no longer deal with dispersed
oases of civilization that barely affect each other.
We have created a global system that is closely
coupled and crises in one location send waves
of disruption throughout the system. The fact
that we live in a globalized system creates new
opportunities, but also increases our risks, since
there may be no refugia in case of a collapse. It will
be unlikely that one developed country or region
will be able to maintain its high quality of life if the
rest of the world will be in substantial crisis. We
have become very interdependent worldwide.
At the same time, as humans exert increasing
levels of impact upon the Earth’s life support system,
they are creating increasingly complex systems
of governance. The democratic decision support
system is robust and resilient, and it maintains itself
very well. However, it is not efficient in times of
crisis, when fast decisions and actions are required.
The checks and balances, which are essential for
the maintenance of the democracies, slow down the
change that may be needed for a fast response. As
the complexity of the governance system increases,
it becomes harder to expect average voters to have
the level of education and knowledge needed to
make the right decisions or the initiative to stay
involved. It becomes even more natural to delegate
the decision making to elected officials who know
what they are doing. At the same time, that may
erode the democratic process, as the knowledge gap
between well-informed officials and the general
electorate grows. This degrades the democracy and
requires further checks and balances that impede
decision-making.
The democratic process draws from market-
Figure 3. Relationship between gross domestic product per capita and life quality indices calculated for 97
countries.
Voinov and Cardwell26
Journal of Contemporary Water researCh & eduCationUCOWR
L
if
e
ex
pe
ct
an
cy
(
ye
ar
s)
L
if
e
sa
ti
sf
ac
ti
on
in
de
x
Page 11
based mechanisms and incentives, and, in turn,
creates them. In some cases these mechanisms can
be very effective to decentralize decision-making
and streamline it by making market forces guide
the system. However, markets are never perfect
and operate under strict regulations that can skew
the playing field through subsidies and regulations.
Besides, markets are blind to substantial human
needs and treat critical natural capital and resources,
such as energy and water, as any other goods and
services. As a result, laissez fair markets can easily
disrupt the system if they are not regulated.
The World Bank predicts that two-thirds of
the world’s population will run short of adequate
water in the next 20 years. This clearly makes
water a very lucrative target for privatization and
speculations. We see this happening around the
world as well as in this country (Hightower 2002).
In many cases, privatization seems like a
simple solution for Federal and state governments
to fix the aging infrastructure that, according
to estimates, may need up to $11 billion more
each year than it gets. However, in most cases
privatization inevitably leads to price hikes (25
percent and more), charges for public services such
as fire hydrants, and overall less security in water
supply. Whenever we deal with critical natural
capital there seems to be an urgent need for strong
governmental regulation and control over privately
managed resources. Privatization can easily
exclude huge numbers of consumers making water
unaffordable to low income families. As with other
critical natural capital, this is not an option. Public
partnerships and cooperatives seem to be far more
promising to handle this (Water for all 2007).
Clearly we need a quantum reduction in demand.
This is the most obvious low-cost solution. Both
energy and water use in the U.S. exceed all
estimates of real needs by an order of magnitude.
There are several ways to decrease demand:
Increase efficiency (which actually is an
alternative to increasing supply)
Use market tools and mechanisms:
- Tax luxury consumption
- Increase prices
- Encourage more use of increasing block rates
Use regulation:
- Penalize luxury consumption
- Peg water pricing to income levels
•
•
•
A combination of these methods will be in order.
Despite likely and justified concerns from the
environmental community, more dam construction
may be a reasonable alternative to control both
water supply and release. As more frequent extreme
water events (droughts and floods) brought by
climate change will require additional regulation
capability, dams will become essential means of
mitigation and adaptation. Such dams can also be a
source of additional hydropower.
Increasing transportation costs will be calling
for more closed and locally self-sufficient systems.
Small hydro, wind, solar, and biogas installations
can help produce additional energy at the point of
service, reducing conversion losses. They will also
help lower water demands and will provide essential
stability for the whole system. A distributed
network is more stable than a centralized one and
is better suited to deal with emergencies to avoid
such repercussions as the countrywide gasoline
price hike as a result of a hurricane in Louisiana.
Local water storage in small cisterns, pools, or
underground reservoirs will decrease flooding and
erosion, and can help recharge the groundwater
supply.
Acknowledgements
We respectfully acknowledge the valuable
suggestions and stimulating discussions that we
had with Norman H. Starler, Stacy Langsdale,
Mark Holtzapple, and Nate Hagens. Gerald Sehlke
has diligently edited the manuscript, considerably
improving it.
End Notes
The Swiss RE web site states: “Today, global
warming is a fact. Since the beginning of
industrialization and the rapid growth of world
population, man’s activities – along with natural
variability – have contributed to a change of climate
manifesting itself as a considerable increase in
global temperature. Climate change has the potential
to develop into our planet’s greatest environmental
challenge of the 21st century.” (http://www.swissre.
com/INTERNET/pwswpspr.nsf/fmBookMarkF
rameSet?ReadForm&BM=http://www.swissre.
com/INTERNET/pwswpspr.nsf/alldocbyidkeylu/
ULUR-6SGFZA? OpenDocument&PT=Swiss+Re-
Our+position+and+objectives).
1.
27
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
creates them. In some cases these mechanisms can
be very effective to decentralize decision-making
and streamline it by making market forces guide
the system. However, markets are never perfect
and operate under strict regulations that can skew
the playing field through subsidies and regulations.
Besides, markets are blind to substantial human
needs and treat critical natural capital and resources,
such as energy and water, as any other goods and
services. As a result, laissez fair markets can easily
disrupt the system if they are not regulated.
The World Bank predicts that two-thirds of
the world’s population will run short of adequate
water in the next 20 years. This clearly makes
water a very lucrative target for privatization and
speculations. We see this happening around the
world as well as in this country (Hightower 2002).
In many cases, privatization seems like a
simple solution for Federal and state governments
to fix the aging infrastructure that, according
to estimates, may need up to $11 billion more
each year than it gets. However, in most cases
privatization inevitably leads to price hikes (25
percent and more), charges for public services such
as fire hydrants, and overall less security in water
supply. Whenever we deal with critical natural
capital there seems to be an urgent need for strong
governmental regulation and control over privately
managed resources. Privatization can easily
exclude huge numbers of consumers making water
unaffordable to low income families. As with other
critical natural capital, this is not an option. Public
partnerships and cooperatives seem to be far more
promising to handle this (Water for all 2007).
Clearly we need a quantum reduction in demand.
This is the most obvious low-cost solution. Both
energy and water use in the U.S. exceed all
estimates of real needs by an order of magnitude.
There are several ways to decrease demand:
Increase efficiency (which actually is an
alternative to increasing supply)
Use market tools and mechanisms:
- Tax luxury consumption
- Increase prices
- Encourage more use of increasing block rates
Use regulation:
- Penalize luxury consumption
- Peg water pricing to income levels
•
•
•
A combination of these methods will be in order.
Despite likely and justified concerns from the
environmental community, more dam construction
may be a reasonable alternative to control both
water supply and release. As more frequent extreme
water events (droughts and floods) brought by
climate change will require additional regulation
capability, dams will become essential means of
mitigation and adaptation. Such dams can also be a
source of additional hydropower.
Increasing transportation costs will be calling
for more closed and locally self-sufficient systems.
Small hydro, wind, solar, and biogas installations
can help produce additional energy at the point of
service, reducing conversion losses. They will also
help lower water demands and will provide essential
stability for the whole system. A distributed
network is more stable than a centralized one and
is better suited to deal with emergencies to avoid
such repercussions as the countrywide gasoline
price hike as a result of a hurricane in Louisiana.
Local water storage in small cisterns, pools, or
underground reservoirs will decrease flooding and
erosion, and can help recharge the groundwater
supply.
Acknowledgements
We respectfully acknowledge the valuable
suggestions and stimulating discussions that we
had with Norman H. Starler, Stacy Langsdale,
Mark Holtzapple, and Nate Hagens. Gerald Sehlke
has diligently edited the manuscript, considerably
improving it.
End Notes
The Swiss RE web site states: “Today, global
warming is a fact. Since the beginning of
industrialization and the rapid growth of world
population, man’s activities – along with natural
variability – have contributed to a change of climate
manifesting itself as a considerable increase in
global temperature. Climate change has the potential
to develop into our planet’s greatest environmental
challenge of the 21st century.” (http://www.swissre.
com/INTERNET/pwswpspr.nsf/fmBookMarkF
rameSet?ReadForm&BM=http://www.swissre.
com/INTERNET/pwswpspr.nsf/alldocbyidkeylu/
ULUR-6SGFZA? OpenDocument&PT=Swiss+Re-
Our+position+and+objectives).
1.
27
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
Page 12
Author Bios and Contact Information
Alexey Voinov, PhD, is Associate Professor at the
International Institute for Geo-information Science and
Earth Observation (ITC). Prior to that Dr.Voinov was
coordinating the Chesapeake Research Consortium
Community Modeling Program, and was also Principle
Research Scientist at John’s Hopkins University. He has
spent one year with the AAAS Science and Technology
Fellowship program working with the Army Corps of
Engineers Institute for Water Resources. Before that he
was with the Institute for Ecological Economics, first
at Univ. of Maryland, and, later - Vermont, working on
integrated studies of the ecological and human dynamics
and sustainability sciences. His academic and teaching
interests evolve around modeling of various ecosystems,
with applications to environmental and integrated
assessment, management and decision support. He is a
keen advocate of stakeholder involvement in modeling
and decision making. Dr. Voinov is Editor of the
Journal for Environmental Modeling and Software and
President of the International Environmental Modeling
and Software Society. His recent book is on “Systems
Science and Modeling for Ecological Economics”
(Academic Press/Elsevier). He can be contacted at
+31(0) 53 487 4507 or email: aavoinov@gmail.com.
Hal Cardwell is with the Corps of Engineer’s Institute
for Water Resources, and is presently leading the Corps
new Conflict Resolution and Public Participation Center
www.iwr.usace.army.mil/cpc/, as well as the conceptual
development, case studies, and outreach to promote
collaborative modeling approaches for water conflict
resolution www.sharedvisionplanning.us. Prior to
coming to the Corps in 2002, Dr. Cardwell was with Oak
Ridge National Laboratory’s Environmental Sciences
Division for a decade, including five years on loan to
the US Agency for International Development (USAID)
working globally and then in Panama on water issues.
Dr. Cardwell is functionally fluent in Spanish, holds
a Ph.D. in Geography & Environmental Engineering
from the Johns Hopkins University. He can be reaches
at 703-428-9071 or Hal.E.Cardwell@usace.army.mil.
References
Aden, A., M. Ruth, K. Ibsen, J. Jechura, K. Neeves,
J. Sheehan, and B. Wallace, L. Montague, A.
Slayton, and J. Lukas. 2002. Lignocellulosic
Biomass to Ethanol Process Design and Economics
Utilizing Co-Current Dilute Acid Prehydrolysis
and Enzymatic Hydrolysis for Corn Stover, NREL
technical report, NREL/TP-510-32438, 154 p. http://
www.osti.gov/bridge/product.biblio.jsp?query_
id=1&page=0&osti_id=15001119.
Anderson, C. 1999. Energy Use in the Supply, Use,
Disposal of Water in California, California Water
Commission Report.
Berndes, G., C. Azar, T. Kaberger, and D. Abrahamson.
2001. Biomass & Bioenergy 20:371-383.
Brown, L. R. 2006. Plan B 2.0: Rescuing a Planet Under
Stress and a Civilization in Trouble, New York: W.W.
Norton & Company.
Cesar B. G., L. Zhu, and M. T. Holtzapple. 2007.
Sustainable Liquid Biofuels and their Environmental
Impact. Environmental Progress, Vol. 26 (3): 233-
250. Published online: 14 Jun 2007, Available at
http://www3.interscience.wiley.com/cgi-bin/abstract
/114279789/ABSTRACT.
Chapagain, A. K. and A. Y. Hoekstra. 2004. Water
footprints of nations. Volume 1: Main Report. Value
of Water Research Report Series No. 16. UNESCO-
IHE Delft.
CNA. 2007. National Security and the Threat of Climate
Change. Report of the Military Advisory Board.
Available at http://securityandclimate.cna.org.
Dominguez-Faus, R., J. G. Burken, P. J. Alvarez. 2009.
The Water Footprint of Biofuels: A Drink or Drive
Issue? - Environ. Sci. Technol. 43 (9): 3005–3010.
Dutta, A. and Phillips, S. D. 2009. Thermochemical
Ethanol via Direct Gasification and Mixed Alcohol
Synthesis of Lignocellulosic Biomass, NREL
technical report, NREL/TP-510-45913, 144 p. http://
www.osti.gov/bridge/product.biblio.jsp?query_
id=3&page=0&osti_id=962020 Dziegielewski B.,
and J. C. Kiefer. 2006. U.S. Water Demand, Supply
and Allocation: Trends and Outlook. Final Report to
U.S. Army Corps of Engineers Institute for Water
Resources. W912HQ-04-D-0007, 88 pages.
Energy Information Administration. 2009. http://www.
eia.doe.gov/emeu/international/energyconsumption.
html.
Farley, J. and E. Gaddis. 2007. An ecological economic
assessment of restoration. In J. Aronson, S. Milton
and J. Blignaut. Restoring Natural Capital: Science,
Business and Practice. Island Press: Washington,
D.C.
Fishman, C. 2007. Message in a Bottle. FastCompany.
Dec. 2007. http://www.fastcompany.com/magazine
/117/features-message-in-a-bottle.html.
Fort, D.D. 1998. (Ed.) Water in the West: challenge
for the next century. Final report of the Western
Water Policy Review Advisory Commission.
University of New Mexico (UNM), 378 p. http://
www.preventionweb.net/english/professional/
Voinov and Cardwell28
Journal of Contemporary Water researCh & eduCationUCOWR
Alexey Voinov, PhD, is Associate Professor at the
International Institute for Geo-information Science and
Earth Observation (ITC). Prior to that Dr.Voinov was
coordinating the Chesapeake Research Consortium
Community Modeling Program, and was also Principle
Research Scientist at John’s Hopkins University. He has
spent one year with the AAAS Science and Technology
Fellowship program working with the Army Corps of
Engineers Institute for Water Resources. Before that he
was with the Institute for Ecological Economics, first
at Univ. of Maryland, and, later - Vermont, working on
integrated studies of the ecological and human dynamics
and sustainability sciences. His academic and teaching
interests evolve around modeling of various ecosystems,
with applications to environmental and integrated
assessment, management and decision support. He is a
keen advocate of stakeholder involvement in modeling
and decision making. Dr. Voinov is Editor of the
Journal for Environmental Modeling and Software and
President of the International Environmental Modeling
and Software Society. His recent book is on “Systems
Science and Modeling for Ecological Economics”
(Academic Press/Elsevier). He can be contacted at
+31(0) 53 487 4507 or email: aavoinov@gmail.com.
Hal Cardwell is with the Corps of Engineer’s Institute
for Water Resources, and is presently leading the Corps
new Conflict Resolution and Public Participation Center
www.iwr.usace.army.mil/cpc/, as well as the conceptual
development, case studies, and outreach to promote
collaborative modeling approaches for water conflict
resolution www.sharedvisionplanning.us. Prior to
coming to the Corps in 2002, Dr. Cardwell was with Oak
Ridge National Laboratory’s Environmental Sciences
Division for a decade, including five years on loan to
the US Agency for International Development (USAID)
working globally and then in Panama on water issues.
Dr. Cardwell is functionally fluent in Spanish, holds
a Ph.D. in Geography & Environmental Engineering
from the Johns Hopkins University. He can be reaches
at 703-428-9071 or Hal.E.Cardwell@usace.army.mil.
References
Aden, A., M. Ruth, K. Ibsen, J. Jechura, K. Neeves,
J. Sheehan, and B. Wallace, L. Montague, A.
Slayton, and J. Lukas. 2002. Lignocellulosic
Biomass to Ethanol Process Design and Economics
Utilizing Co-Current Dilute Acid Prehydrolysis
and Enzymatic Hydrolysis for Corn Stover, NREL
technical report, NREL/TP-510-32438, 154 p. http://
www.osti.gov/bridge/product.biblio.jsp?query_
id=1&page=0&osti_id=15001119.
Anderson, C. 1999. Energy Use in the Supply, Use,
Disposal of Water in California, California Water
Commission Report.
Berndes, G., C. Azar, T. Kaberger, and D. Abrahamson.
2001. Biomass & Bioenergy 20:371-383.
Brown, L. R. 2006. Plan B 2.0: Rescuing a Planet Under
Stress and a Civilization in Trouble, New York: W.W.
Norton & Company.
Cesar B. G., L. Zhu, and M. T. Holtzapple. 2007.
Sustainable Liquid Biofuels and their Environmental
Impact. Environmental Progress, Vol. 26 (3): 233-
250. Published online: 14 Jun 2007, Available at
http://www3.interscience.wiley.com/cgi-bin/abstract
/114279789/ABSTRACT.
Chapagain, A. K. and A. Y. Hoekstra. 2004. Water
footprints of nations. Volume 1: Main Report. Value
of Water Research Report Series No. 16. UNESCO-
IHE Delft.
CNA. 2007. National Security and the Threat of Climate
Change. Report of the Military Advisory Board.
Available at http://securityandclimate.cna.org.
Dominguez-Faus, R., J. G. Burken, P. J. Alvarez. 2009.
The Water Footprint of Biofuels: A Drink or Drive
Issue? - Environ. Sci. Technol. 43 (9): 3005–3010.
Dutta, A. and Phillips, S. D. 2009. Thermochemical
Ethanol via Direct Gasification and Mixed Alcohol
Synthesis of Lignocellulosic Biomass, NREL
technical report, NREL/TP-510-45913, 144 p. http://
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29
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
Greer J. M. 2004. The Long Road Down: Decline and
the Deindustrial Future, http://www.oilcrisis.com/
whatToDo/decline.htm.
Guinée, Jeroen B. 2002. (Ed.) Handbook on Life Cycle
Assessment, Operational Guide to the ISO Standards,
704 p.
Hall, C. A. S., R. G. Pontius, J. Y. Ko, and L. Coleman.
1994. The environmental impact of having a baby
in the United States. Population and Environment
15:505-524.
Hightower, J. 2002. Taking our common wealth and
selling it. Stop the corporate takeover of our water.
Hightower Lowdown, June 2002, Vol. 4 (6). http://
www.hightowerlowdown.org/node/205.
Hubbert, M. K. 1974. On the Nature of Growth.
Testimony to Hearing on the National Energy
Conservation Policy Act of 1974, hearings before
the Subcommittee on the Environment of the
committee on Interior and Insular Affairs House of
Representatives. June 6, 1974. Tuesday, February 27,
2007 - Technocracy.org.
Hutson, S. S., Nancy L. Barber, Joan F. Kenny, Kristin S.
Linsey, Deborah S. Lumia, and Molly A. Maupin et
al. 2004. Estimated Use of Water in the United States
in 2000, Circular 1268, U.S. Geological Survey.
International Standard Organization. 2006. Environmental
management - Life cycle assessment - Requirements
and guidelines, ISO 14044:2006, 46 p.
Kannan, R., C. Tso, R. Osman, and H. Ho. 2004. Energy
Con. and Mgmt 45:3093-3107.
Marano, J. J., Ciferno, J.P. 2001. Life-cycle greenhouse-
gas emissions inventory for Fischer–Tropsch
fuels. Report Prepared for the US Department of
Energy, Energy and Environmental Solution, LLC,
Gaithersburg, MD, USA.
Middlebrooks, E. J. and C. J. Middlebrooks. 1979.
Energy Requirements for Small Flow Wastewater
Treatment Systems. Reprint of CRREL SR 79-7.
MCD-60, OWPO, USEPA. April 1979.
Mubako, S and Lant, C. 2008. The water resource
requirements of cron-baed ethanol. Water Resources
Research 44, W00A02, doi:10.1029/2007WR006683,
2008.
Mulder, K., N. Hagens, and B. Fisher. 2007. Burning
Water: A Comparative Analysis of the Energy Return
on Water Invested. In review for Ambio.
New Economics Foundation. 2006. New Economics
Foundation Life Satisfaction Index.
Phillips, S., Aden, A.. Jechura, J., Dayton, D..
Eggeman, T. 2007. Thermochemical Ethanol via
Indirect Gasification and Mixed Alcohol Synthesis
of Lignocellulosic Biomass, NREL technical
report, NREL/TP-510-41168, 132 p. http://
www.osti.gov/bridge/product.biblio.jsp?query_
id=3&page=0&osti_id=902168.
Shannon, M. A. 2007. Energy Dependence on
Waters, Waters Dependence on Energy. Center of
Advanced Materials for the Purification of Water
with Systems, Texas Water Development Board
2007 Plan and Projections. http://www.twdb.state.
tx.us/publications/reports/State_Water_Plan/2007/
2007StateWaterPlan/2007StateWaterPlan.htm.
Spreng D. T. 1988. Net energy requirements and the
energy requirements of energy systems. New York:
Praeger Press.
Torcellini, P, N. Long, and R. Judkoff. 2003.
Consumptive Water Use for U.S. Power Production.
NREL/TP-550-33905, 18 p., http://www.nrel.gov/
docs/fy04osti/33905.pdf.
U. S. Census. 2009. http://www.census.gov/main/www/
popclock.html.
U. S. Department of Energy. 2006. Report to Congress
on the Interdependency of Energy and Water,”
December 2006, page 60.
Wallerstein, I. 2003. The Ecology and the Economy:
What is Rational? Paper delivered at Keynote
Session of Conference, World System History and
Global Environmental change,” Lund, Sweden, 19-
22 September 2003. http://www.binghamton.edu/
fbc/iwecoratl.htm.
Water for all. 2007. Turning Up the Tap. How the
Private Water Industry Wants to Boost Profits – at the
Expense of Taxpayers. Public Citizen, http://www.
citizen.org/cmep/Water/articles.cfm?ID=10842.
29
UCOWR
The Energy-Water Nexus: Why Should We Care?
Journal of Contemporary Water researCh & eduCation
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