摘要
Global food and feed demands have been projected to double in the 21st century, which will further increase the pressure on the use of land, water and nutrients. At the same time, the political decisions to support renewable energy sources are accelerating the use of biomass, including grain, sugar, oilseed, and lignocellulosic crops for biofuel and power generation. Government directives — incited by climate change, high oil prices and geo-political tensions — promote partial replacement of fossil fuel by biofuels. Prices and availability of commodities used as staple food and feed are becoming already affected by the growing demand for bioenergy. Many implications of this demand for biofuel on the resource base (land, water, biodiversity), environment, rural economy, food prices and social impacts are unknown. The present study reviews and discusses the opportunities and limits of crops and resources for food, feed and biofuel production. There are gaps in our knowledge regarding the global capacity for sustainable plant-based bioenergy production, while maintaining food security; commercial biomass production will compete with food crops for arable land and scarce fresh water resources. The rapidly growing demand for food, feed and fuel will require a combination of further increases in crop yields (ca. 2 % per annum) and a doubling or tripling of resource-use efficiencies, especially of nitrogen-use efficiency and water productivity in production systems with high external inputs, over the next 20 to 30 years. Adaptation of cropping systems to climate change and a better tolerance to biotic and abiotic stresses by genetic improvement and by managing diverse cropping systems in a sustainable way will be of key importance. An integrated assessment of resource-use efficiencies, ecological services and economic profitability may guide the choice of crop species and cultivars to be grown in a target environment and region, depending on the added value for specific purposes: food, feed or fuel. To avoid negative impacts on food security, governments should give high priority to 2nd, 3rd and 4th generation technologies for bioenergy.