Tuesday, 17 February 2009

Food scraps and farm waste to be chewed up to create energy

(click headline for original article)
Food scraps and farm waste to be chewed up to create energy
… and who would wonder, its all about money. Or bankers? Or both?

There are opportunities, but then there is lots that can go wrong.

Germany has more than 3,500 of those bio digesters, biogas-plants, fermenters, call them what you like; not that all the farmers fell in love with the beautifully designed, tent like covered, round, greenish painted swimming pools or the loud and smelly engines. No, there is no love involved, but incentives, money; very attractive feed-in tariffs led to these monsters becoming a “must-have” for any clever farmer boy.

Soon farmers’ bankers and financiers saw the opportunity to print money; more so if the scale was taken beyond the normal farmers’ thinking pattern; slurry is fine, but lots of it and a mix of wheat flour and energy maize is much better; loads of maize, transported from close and far away neighbouring farmers contracted to grow nothing else but maize; bigger plants and optimized technologies, driving efficiencies (= kWe output) higher and higher.

The efficiency though is that of the financial model leaving way behind the original idea of utilising a natural process. Nature as in “little bacteria fermenting under controlled conditions what is becoming a growing threat to the environment” (slurry > methane from mass farming) and convert it into bio or renewable energy by producing methane which drives a gas engine generating decentralised electricity and (hopefully) the farmer taking advantage of the thermal energy (heat) as well.

By optimising the mix, stirring it, warming it up to 37°C the “energy farmer” utilises the most efficient first 30 or 35 bacteria working days, optimal conditions for his little helpers making the engines run at their highest efficiency rates; re-charging the pool with a fresh, loaded slurry mix makes the bacteria work harder again, the engines keep on running hard, the kW metres top up the purse.

What is pumped out – long before it can be used as just-a-fertiliser - from the fermenters onto open fields is still the same mix of slurry plus ambitiously grown, fertilised, harvested, chipped and transported energy maize plus the intensively farmed wheat flour, while the former hard working bacteria are now slowing down having to go another two thirds of the way until the mix is sorted out and the fermenting process is running out of food. With other words the optimised business plan of any biogas plant takes into account that approximately one third of the methane will be generating electricity and heat, but the remaining two thirds will go the same path into the environment as before. These remaining two thirds of an optimised mix is producing far more GHG (green house gases) than that of slurry spread on fields prior to the incentives creating the new financial model of biogas plants. The incentives are paid for the electricity fed back into the grid no matter how much methane leftovers there are and whether or not the heat is utilised wisely.

By the way, the mix works even better with water instead of slurry, less contamination and the smell is not as bad. It is still biogas, though.

Carpe diem.


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