N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels |
Jun 2007
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N2O, a by-product of fixed nitrogen application in agriculture, is a “greenhouse gas” with a 100-year average global warming potential (GWP) 296 times larger than an equal mass of CO2. As a source for NOx, i.e. NO plus NO2, N2O also plays a major role in stratospheric ozone chemistry.
The increasing use of biofuels to reduce dependence on imported fossil fuels and to achieve “carbon neutrality” will further cause atmospheric N2O concentrations to increase, because of N2O emissions associated with N-fertilization.
Here a global average criterion for the ratio of N to dry matter in the plant material is proposed, which indicates to what degree the reduced global warming (“saved CO2”) achieved by using biofuels instead of fossil fuel as energy sources is counteracted by release of N2O.
This study shows that the use of several agricultural crops for biofuel production and climate protection can readily lead to enhanced greenhouse warming by N2O emissions.
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