Bioenergy
Bioenergy crops can reduce or offset greenhouse gas emissions by removing carbon dioxide from the air as they grow and storing it in crop roots and soil as organic carbon; by producing co-products like protein for animal feed, and by displacement of fossil fuels.
However, biofuel crops have distinctive greenhouse gas balances, which may also be negative depending on the production methods, the location and the degree to which direct and indirect land use changes are considered in the life cycle analysis. For example, while maize produced for ethanol can generate GHG savings of about 1.8 tons per ha/yr, and switchgrass of 8.6 tons per ha/yr, conversion of grassland and forest can release 300 tons/ha and 1 600-1000/2ha, respectively. Good agricultural practices and integrated food-energy production systems can partially mitigate this damage. Compared with other options, liquid biofuels are typically a very costly means of reducing greenhouse gases. Evidence suggests that carbon taxes, tradable permits and energy conservation may be more cost-effective than biofuels in reducing greenhouse gas emissions.
Wood based-energy is currently the most important source of renewable energy worldwide and can contribute to climate change mitigation through the displacement of carbon emissions from fossil fuels. In fact, net carbon emissions from generation of a unit of heat or electricity from wood energy are 10 to 20 times lower than emissions from fossil fuel-based energy. However, one has to account for the removal of woody biomass in the GHG balance, even if it is renewable. To date, most wood energy applications utilize feedstock from unsustainably managed forest land, with few “bioenergy crops” specifically grown for that purpose. However, with increasing oil prices and new technologies, there will be an increase in the demand for woodfuel from energy plantations which can provide a carbon ‘sinks’ when complemented with other better managed feedstock sources.
Key FAO Links
- Global Bioenergy Partnership (GBEP): Bioenergy and Climate Change publications
- Bioenergy and Food Security (BEFS) Project
- FAO and Bioenergy
- FAO Climate Change and Bioenergy Unit
Contact
Page content: Olivier.Dubois@fao.org (NRCB)
Environment, Climate Change and Bioenergy Division: NRC-Director@fao.org