Oct
22
Germans Look to Straw For Fuel
October 22, 2013 | 1 Comment
Straw, the stem and some of the leaves of cereal grasses like wheat, oats and rye grasses could be seen as under utilized as a biomass residue and waste material. Keeping straw on the farm is also a valid way to not deplete and protect soils. The biomass of straw is a very interesting commodity, however.
Straw could supply energy to several millions of households in Germany. Image Credit: Stefan Michalski/ UFZ. Click image for the largest view.
The German research suggests using the nation’s straw in part could provide 1.7 to 2.8 million average households with electricity and at the same time 2.8 to 4.5 million households with heating.
The results highlight the potential contribution of straw to renewable sources of energy. The TLL scientists published their results in the peer-reviewed scientific journal Applied Energy.
From the scientists point of view in the study they analyzed the development of residual substances resulting from German agriculture. Accounting for 58%, straw can be regarded as the most important resource, and yet so far it has hardly been used for energy production.
From 1950 to 2000 there was a noticeable rise in the cultivation of winter wheat, rye and winter barley in Germany, which then remained relatively constant. To remove any bias from weather fluctuations, the average values were taken from 1999, 2003 and 2007. On average, approx. 30 megatons of cereal straw per year were produced in these years. Due to the fact that not all parts of the straw can be used and the fact that straw also plays an important role as bedding in livestock farming, only about half of these 30 megatons are actually available in the end.
The German team also considered that cereal straw plays an important role in the humus balance of soils. For this reason some of the straw must be left scattered on the agricultural land to prevent nutrients from being permanently extracted from the soil. To calculate the humus balance of soils, the team of scientists tested three different methods of calculation.
Depending upon the method of calculation used, 8, 10 or 13 megatons of straw can be used sustainably every year for energy production – i.e. without causing any disadvantages to the soils or other forms of utilization. “To our knowledge this is the first time that a study like this has been conducted for an EU country, demonstrating the potential of straw for a truly sustainable energy use, while taking into account the humus balance,” stresses Prof. Daniela Thraen, scientist at the DBFZ and the UFZ.
Straw could contribute to the future energy mix.
Political correctness requires assessing to what degree straw use will contribute to greenhouse gas reduction. But, that depends on how the straw is used. A reduction compared to fossil fuels can be somewhere between 73 and 92 percent when using straw for the generation of heat, combined heat and power generation or as second-generation biofuel production. The different greenhouse gas balances cast a differentiated light on the European Union’s goal of covering ten percent of transportation sector’s energy use by using biofuels.
Once again the study emphasizes how the use of bioenergy needs to take into account various factors. Given the conditions prevalent in Germany, the use of straw in combined heat and power generation would be best for the climate. “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 utilization,” stresses Dr. Armin Vetter from TLL, who has been operating a straw-fuelled power station for 17 years.
According to the summary of the new study, straw-based energy applications should be developed in Germany in particular in those regions with favorable conditions and appropriate power plants.
All this wouldn’t be spinning straw into gold. But, Denmark is considered to be the world leader in straw-based energy applications. 15 years ago a master plan was introduced there, ensuring in the meantime in Germany´s northern neighboring country that over 5 billion kilowatt hours of energy per year is generated from straw.
These kinds of biomass ideas could very well work. The problem is soil depletion, the removal of the phosphorus and potassium and the other trace elements. One field of research sorely missed is a means to recover the fertility elements and send them back to the land at affordable cost.
Then these kinds of ideas would have a much better chance of making economic sense.
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The fact that they are acknowledging the important role straw plays on the farm is encouraging. They realize you cannot take it all without adverse effects.
“You can sheer a sheep many a time, but you can only skin him once.”