In the study, fields and pastures for food production were excluded from land use change to plantations for dedicated energy crops. These areas, the scientists assume, are going to be needed for feeding the world population which will very likely grow by two billion people by the mid of this century. Also, areas of untouched wilderness or high biodiversity have been excluded, as well as those forests or peatlands which store large amounts of the greenhouse gas carbon dioxide. For the whole Earth’s surface cultivation conditions of plants like poplar, eukalyptus and switchgrass were analysed – all being energy crops of the so-called second generation, not of the first generation comprising food crops like maize or rape.
Following these criteria, the computer simulation shows the spatial distribution of potential cultivation areas. In theses areas, bioenergy production would be more environmentally sustainable than in other places. Still, sensitive areas like the grasslands of the Humid Pampa in South America would be touched, the study says. It just got published in the journal 'Global Change Biology - Bioenergy'. The research project has been funded by the Leibniz Scientific Community's promotion of excellence program with one million euros.
The researchers ran a whole set of scenarios for biomass plantations. The bioenergy potential ranges from 25 to 175 exajoule by year: lower outcome with strong land use restrictions and without irrigation, higher outcome with little land use restrictions and strong irrigation. A middle scenario would result in about 100 exajoule, while the world's energy consumption is estimated to double from today's 500 to 1000 exajoule in the year 2050. Roughly the same amount of energy production, in addition to biomass plantations, could result from agricultural residues.
“Without energy production from biomass, according to many studies, ambitious goals of climate protection would be hardly achievable,“ PIK research domain chair Wolfgang Lucht says. He explains that a limitation of global warming to two degrees Celsius above preindustrial level would quite inevitably require twenty percent of bioenergy. “How much energy can be produced at which environmental costs therefore is a critical and controversial question.“ Plantations with dedicated energy crops will play an especially important role in the future, the scientists assume. Studies estimating their potential, however, are “in many cases too optimistic“ and neglect the environmental costs, Lucht says. Often, global agricultural yield increases are assumed to make important areas available for the cultivation of dedicated energy crops. This view neglects that the global demand for food is growing – and that water scarcity in many areas limits the intensification of agriculture.
Land use change will contribute to energy security and rural
development only if it is internationally coordinated and regionally
adapted, the PIK-researchers conclude. A biomass certification
scheme could be beneficial. Most notably an increased use of
agricultural residues instead of cultivating dedicated energy crops
could be an important contribution to sustainability.
Article: Beringer, T.,
Lucht, W., Schaphoff, S.: Bioenergy production potential of global
biomass plantations under environmental and agricultural
constraints. GCB Bioenergy, 2011
[doi:10.1111/j.1757-1707.2010.01088.x]
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