28.05.2010

Global biomass potential under sustainable constraints

Quelle: European Commission

Biomass is increasingly used to make biofuels and generate electricity and is seen as a valuable source of renewable energy. A recent study has assessed the key factors relating to the sustainability of bioenergy production and suggests global biomass could potentially meet up to one third of the projected global energy demand in 2050.

There is ongoing debate about the sustainability of the future production of biomass, with concerns over its effect on food production and prices, biodiversity, and water and land resources. Nevertheless it is anticipated and expected that biomass will become a significant and necessary source of renewable energy in the future.

This study assessed the energy potentials of biomass by conducting an extensive review and sensitivity analysis of earlier research. Key uncertainties were evaluated in order to estimate their impact on the role of biomass as a sustainable source of energy.

Previous studies on the global energy potentials of biomass differ widely: from 1500 EJ (the highest technical potential) to 100 EJ (Exajoule = 1018 J), using residues only, in 2050. When constraints on biomass production are considered, the range of biomass potentials falls to about 200-500 EJ per year. With biomass demand estimated to be between 50 and 250 EJ in 2050, biomass could, in principle, meet up to one third of the global energy use, which is predicted to be about 600-1040 EJ per year.

Projected demand for food varies widely and depends on global population growth and dietary trends. The land requirements for food production depend heavily on advances in agricultural technology and future economic growth. Changes in the relative prices of agricultural commodities and different energy sources are seen as key drivers for future use of biomass and land.

Bioenergy production affects biodiversity on different levels. Local biodiversity may benefit from the growing of biomass, for example, when intensive agricultural practices are replaced by low-intensity biomass production systems. In general, mixed cropping systems and perennial woody and herbaceous crops do better than annual agricultural crops at the local level. Land use change at the global level may lead to reductions in biodiversity, but this depends heavily on land use management and land use planning. In the long-term, bioenergy is expected to contribute to a reduction in GHG emissions which in turn is expected to reduce the negative effects of climate change on biodiversity loss.

Demand for water is expected to increase in the coming years, generally reducing the availability of water in most regions, but particularly those where water is already scarce. Opportunities exist for energy crop production where the water supply is abundant and where water use efficiency can be improved. A key factor is the possibility of improving the overall water use efficiency in agriculture as well as in urban uses and thus increasing the biomass potentials.

Sustainable biomass production requires policies that:

1. Balance the production of food, animal feed and biomass by improving agricultural management and use of marginal and degraded land to grow perennial lignocellulosic crops, which generally have higher yields than annual crops and provide more possibilities to meet various sustainability criteria.

2. Address environmental concerns by choosing suitable bioenergy crops and sustainable land use planning

3. Positive GHG balances of bioenergy systems can be secured by choosing suited biomass sources (e.g. using residual biomass and perennial crops), while preventing direct and indirect land use changes.

4. Implement ways to ensure overall sustainability through, for example, biomass certification schemes and proper governance of land use.

Further information:

http://www.bioenergytrade.org/downloads/wabbiomassmainreportbiomassassessment.pdf