CO2 emission from geothermal plants

Abstract

Geothermal energy is considered to be a benign energy source as regardsenvironmental impact. One of its impacts is the release of the greenhouse gas, CO2, to the atmosphere. In a recent survey by the IGA it was shown that in comparison with the burning of fossil fuels there is a considerable advantage to using geothermal energy. Mitigating circumstances for geothermal power plants include the possibility of cascading uses such as industrial production, space heating, greenhouse culture etc. that can be run parallel with the power production and reduce the gas emissionper energy unit. The CO2 emitted from geothermal plants is already part of the CO2 cycle, no new CO2 is being produced as is the case in fossil fuel plants. Furthermore this CO2 is usually removed from the cycle where there is already vigorous degassing from geothermal and volcanic areas and it is possible that the addition to the atmosphere is negligible. Studies already carried out to this effect have in fact suggested that this is the case. Thus it is suggested that background emission from geothermal areas be estimated before the total added from a power plant is estimated.On the basis of the results of such studies Italy has decided not to include geothermal CO2 emission as part of their anthropogenic greenhouse gas emission reported in connection with international agreements. Recently Iceland has decided to take the same course of action.