"Bio-energy - Chances and Limits" is the title of the paper more than 20 scientists have been working on at the German Leopoldina National Academy of Sciences since 2010. But the chemists, biologists, ecologists and climatologists clearly think there are more limits than chances for the meaningful use of renewable resources to produce energy, at least in Germany.

"The current proposal by politicians to have bio-energy supply 23 percent, sometimes even 30 percent of our overall energy supply is entirely illusionary," is the sobering conclusion drawn by Bernhard Schink, one of three coordinators of the study and professor of microbial ecology at the University of Konstanz. Germany is now part of what has become known as the "energy revolution," relying heavily on bio-gas, bio-diesel, and bio-ethanol. German cars, for example, use gasoline or diesel containing 5 to 10 percent ethanol.

Difficulty balancing calculations

There are two basic arguments for the use of bio-energy. The supply of fossil fuels like oil and coal is limited. Importing them creates economic and political dependency. Ever more sophisticated production techniques to extract from "inferior" resources such as oil sands, pose environmental risks. To add to that, the use of fossil fuels releases carbon dioxide, a greenhouse gas responsible for global warming. Bio-energy emits the same amount of CO 2 into the atmosphere that plants consume - at first glance, a balance.

But all climate-related aspects of biomass production have to be taken into account, an approach taken by the Leopoldina study. A complete balance would account for fertilizers, which cause nitrogen-based greenhouse gases to be released, including tractor exhaust fumes when sowing, plowing and harvesting, and even emissions from fertilizer production and transport to the farmer's field. Similarly complicated is the question, how much energy can be "gained" for example with one liter of bio-ethanol? The entire energy consumption throughout the production chain must be taken into consideration.

Areas in Brazil are particuarly suited for the production of biofuels from sugar cane

Shortage of space in Germany

Bio-ethanol only makes sense in a country like Brazil with lots of land, a low population density and a quasi-ideal crop such as sugar cane, the scientists concluded in their report. "In Germany, space is limited, today we import one-third of our total biomass production from abroad, mainly as animal feed." Knowing this, it would be "difficult to justify growing grow 'energy plants,' while importing food from other countries." This outsourcing of agriculture must be included in any overall calculation, Schink said. The study's authors say that only forms of bio-energy "that neither lead to food shortages nor cause food prices to skyrocket" are deserving of support.

Fruit and vegetable waste is a valuable resource

On balance, the Leopoldina scientists think the only reasonable scenario for the use of bio-energy is through the recovery of waste, not only in agricultural areas, but also in towns and cities - that is, the production of bio-gas from materials that would otherwise have ended up in landfills. Instead of adding more biofuel to gasoline, Germany should expand other "renewable" resources, the researchers suggest. Photovoltaic, solar thermal and wind energy are much more efficient and sustainable overall.

Report a "vexatious blunder"

Elmar Baumann, director of the German Biofuel Industry Association (VDB) called the Leopoldina paper a "vexatious blunder." It doesn't offer anything new, "there is data that has already been published elsewhere, it asks questions that have already been asked, so you ultimately have to ask what the point of the study was," he said. Biofuel from German rapeseed makes clear environmental sense, Baumann said. It is regulated and certified: the Biofuel Sustainability Regulation requires industry to reduce greenhouse gas emissions by at least 35 percent compared to fossil fuels. The production chain factors listed in the Leopoldina report, he said, "are included in the balance sheet, meaning it is complete." The scientists, Baumann said, failed to make mention that no alternative exists for bio-diesel or bio-ethanol in transport. The recommendation of solar and wind energy cannot help here, he said.

Bio-ethanol as an interim solution

Schink agrees with the criticism: "Objectively this is absolutely correct, ultimately we are not offering an alternative." However, he says he can imagine saving fossil fuels in other areas of, thus reserving petroleum for internal combustion engines until electric vehicles become more widely used. But the Leopoldina study explicitly cites one example of how bio-ethanol could make economic and environmental sense in Germany: a new technique developed by German researchers at the University of Hohenheim of producing biofuel and bio-gas at the same time. To date this method has only worked on a small scale, "extending it to industrial use would certainly require more development work," Schink said.

Author: Michael Gessat / jlw

Editor: Simon Bone