Bioenergy can turn "Bio"

Energy can be won from maize, rape or other plants, yet the large-scale cultivation of energy plants is not automatically environmentally friendly. “Bioenergy will play a role in many regions of the world, but it will very much depend on how this bioenergy is obtained”, says Dr. Daniela Thrän from the Department Bioenergy of the Helmholtz Centre for Environmental Research - UFZ in Leipzig. The UFZ researchers here work closely together with the German Biomass Research Centre (DBFZ) and investigate how the ground and hydrologic balance change through the cultivation of energy plants and how this affects landscapes and their biodiversity. In doing so, they also assess the greenhouse gas balances, evaluate the various exploitation technologies and their markets and devise recommendations for policy makers.

For instance, enormous cultivation areas destroy habitats for animals and plants and in agriculturally used regions biodiversity is lost at an especially fast rate. A solution could be provided by broader strips between fields, offering sufficient retreats for small animals in form of wild plants and trees.

And this could entail also a financial benefit, Thrän thinks. For in future, wood will be in even higher demand as a source of energy and in principle, the wild growth at the edges of fields could be mown and also used in biogas plants. For instance, the microbiologists at the Department Bioenergy work on improving the bacterial processes in biogas plants in such a manner as to enable the usage of a wide spectrum of residual plant matter. “It is important that this is achieved not only in high-tech plants such as Bioliq at the KIT, where high-quality fuels are being produced, but that small biogas plants on site can also use residual matter for the production of electricity and heat in an improved way”, Thrän explains. In Germany, biological energy sources could cover about 15 percent of the primary energy demand in future, with bioenergy providing advantages over fossil energy sources both in the production of thermal heat and in the utilisation as a fuel.

“However, we model also how the metabolism of the ground, the carbon cycles and water management change through the cultivation of energy plants”, explains Thrän. For example, perennial energy plants such as timber or grasses or mixed crops composed of different plants requiring less fertiliser than food plants are advantageous. This is because fertiliser is produced at a high cost of energy and impairs the CO2 balance of energy plants.

The UFZ researchers around Thrän have developed a consulting tool from which can be derived recommendations as regards the use of certain plants for certain regions and their special grounds and climatic conditions. For instance, maize requires regular precipitation and especially in the middle of Germany it could get significantly dryer over the course of the next decades. “Our research results will contribute to new legal guidelines and funding conditions for the cultivation of energy plants”,Thrän hopes. A uniform solution for all regions will not be possible. It is more important to efficiently use existing residual matter to a greater degree than now and to take the conditions on site into consideration in order to save on fertiliser and not to pollute the ground and hydrologic cycles. If this is the case, then, bioenergy can become much more environmentally friendly.