CO2 emissions and avoidance
Whenever carbon-containing fuels, e.g. fossil fuels, are combusted carbon dioxide (CO2) is released. The amount of CO2 produced depends on the type of fuel and the efficiency of the power plant.
According to the European Commission („An Energy Policy for Europe“), the following emission factors can be assumed:
Emission factors of CO2 equivalents
|Natural gas ||440 g/KWh |
|Oil ||550 g/KWh |
|Coal ||800 g/KWh |
The annual CO2 emissions worldwide amount to about 36 billion te. Most of this is released into the atmosphere and contributes to global warming. Therefore, one goal of the promoting renewable energy sources is the reduction of greenhouse gas emissions.
CO2 reduction through green electricity generation
When biomass is combusted for electricity generation, the amount of CO2 released equals the amount of CO2 the plant has taken out of the atmosphere and stored in its organism during its growth. This method of electricity production is therefore considered carbon neutral. When electricity is generated from other renewable energy sources, no CO2 is emitted at all. Yet, with electricity generation from fossil fuels such as natural gas, oil or coal, CO2 emissions vary from 0.2 to 0.9 te per MWh depending on the fuel and the plant's efficiency. The below graph relates this CO2 reduction effect of green electricity generation to the required financial support, i.e. it shows the cost of avoiding the emission of one tonne of CO2 for the different subsidised technologies (basis: market price of 60 €/MWh). One conclusion to be drawn from the above is that some green electricity technologies constitute relatively expensive measures compared to other CO2 reduction programmes.
CO2 emitted by biofuels in transport The next graph plots the CO2 emissions caused by a number of biofuels.
Each fuel’s emissions are shown as compared to petrol, which is benchmarked at 100%. A gas’s global warming potential describes how much more or less than CO2 it contributes to the greenhouse effect over a period of 100 years.