The Compatibility of Wind and Solar Technology with Conventional Energy Systems

Abstract

Energy converted directly from the sun and the wind is available intermittently. This is qualitatively different from the conventional sources of energy, mineral fuels. Mineral fuels embody energy stored over geologic time. This energy is available to us whenever we have the appropriate combination of supply source and conversion device. Energy converted directly from the sun and wind is an inherently fluctuating source; a random element is fundamental to the nature of the resource. We can count on its "gross availability;" we assume the sun will always be there. But we do not know whether the sun will shine or the wind will blow in any particular period. The supply cannot be directly manipulated to meet the demand. There are some "solar" technologies that do not feature this random availability (e.g. biomass, ocean thermal energy.) These are excluded from the following discussion in order to focus more narrowly on the consequences of uncertain availability. The questions we ask involve the interface of the somewhat random availability technology of wind and solar energy with the energy system based on mineral fuels. Are the two compatible? This question revolves for obvious reasons around the electric utility industry. Most importantly because wind and solar technologies produce electricity or substitutes for electricity. Even in those situations where the substitution or competition effect is relatively weak, electricity can be an attractive supplement or complemento solar energy. The case of electric backup for solar heating, the first concrete compatibility problem to emerge