Plant Oil Fuels Combined Heat and Power (CHP)

Abstract

Glossary Cogeneration Cogeneration, also known as combined heat and power (CHP), describes the simultaneous production of both mechanical energy and useful heat from various sources of energy by a thermo-dynamic process in a technical plant [1, 2]. Combined heat and power plant (CHP Plant) A combined heat and power plant (CHP plant) or cogen-eration plant provides simultaneously electricity and useful heat. Electricity generation efficiency Electricity generation efficiency or electrical efficiency is the ratio between the electricity output and the energy input of an energy conversion system. Whereas small-scale CHP plants with combustion engines feature electricity generation efficiencies of roughly 30%, large-scale CHP plants obtain up to 45% [3, 4]. Energy conversion efficiency Energy conversion efficiency or overall conversion efficiency is the ratio between the useful energy output and the energy input of an energy conversion system. For CHP plants, energy conversion efficiency is the sum of electricity conversion efficiency and heat conversion efficiency. Electrical and thermal auxiliary power for the CHP plant (e.g., for pumps, control unit, fuel preheating, etc.) has to be deducted [3]. Heat generation efficiency Heat generation efficiency or thermal efficiency is the ratio between the useful heat output and the energy input of an energy conversion system. It is the result of the heat extraction by heat exchangers. Here, the temperature level is decisive [3]. Plant oil fuel Plant oil fuel is derived from oil-containing plant parts for the use in plant oil compatible combustion engines. In Germany, for example, plant oil fuel quality is specified by the national pre-standard DIN V 51623 (publication expected in 2011). Power-to-heat ratio Power-to-heat ratio is the ratio between produced electrical and useable thermal energy. It is an evaluation criterion of CHP plants and ranges normally between 0.4 and 0.6. Because the power-to-heat ratio is increasing when heat generation efficiency is decreasing, additionally the energy conversion efficiency has to be specified [3]. Rapeseed oil fuel Rapeseed oil fuel is oil extracted from rapeseed, for the use in plant oil compatible combustion engines. In Germany, for example, rapeseed oil fuel quality is specified by the national standard DIN 51605 [5]. Thermal fuel power Thermal fuel power or rated thermal input describes the fuel heat content on basis of the net calorific value feed into an energy conversion system within a defined period of time [3]. Utilization ratio Utilization ratio of an energy conversion system is the ratio between the usable energy and the energy input within a given period of time.