Straw Discovered as a Potential Sustainable Energy Resource
Straw from agriculture could help address future energy needs, a new study published in the journal Applied Energy suggests.
Led by researchers from the Helmholtz Center for Environmental Research, Thueringian Regional Institute for Agriculture (TLL) and German Biomass Research Center, the report found that of the 30 million tons of cereal straw produced nationally every year, between 8-13 million could be used sustainably for energy or fuel production. This could in turn provide between 1.7-2.8 million households with electricity and 2.8-4.5 million with heating, the researchers estimate.
According to the study, Germany underwent an increase in winter wheat, rye and winter barley production from 1950 to 2000, at which point it plateaued. In all, the researchers determined that 30 megatons (one megaton equals 1 million tons) of cereal straw were produced annually in 1999, 2003 and 2007; however, since not all parts of the straw can be used, and because much of it is employed as bedding for livestock, only about half of this is available in the end. Furthermore, a portion of the straw must be left scattered on the land in order to prevent nutrients from being permanently extracted.
Based on a number of calculations and tests, the scientists determined that either 8, 10 or 13 megatons of straw can be used every year without resulting in any disadvantage either to other forms of utilization or to the soil.
To what degree the use of straw could contribute to a reduction in greenhouse gases depends on how the straw is used, the researchers explain. When replacing fossil fuels in the case of, for example, heat generation, combined heat and power generation or as second-generation biofuel production, the reduction falls between 72 and 92 percent.
Based on current conditions in Germany, the researchers argue that the use of straw in combined heat and power generations would benefit the nation’s climate the most.
“Straw should therefore primarily be used in larger district heating stations and/or combined heat and power stations, but technology must be developed for an environmentally-friendly utilisation,” stressed Armin Vetter from TLL, who has been operating a straw-fuelled power station for 17 years.