A pilot project in Germany is collecting food waste from wholesale fruit and vegetable markets and cafeterias to ferment and make methane, which will then be used to power vehicles that have been converted to run on natural gas.

The pilot plant has been developed by the Fraunhofer Institute for Interfacial Engineering and Biotechnology and is located next to Stuttgart's wholesale produce market for easy access to food waste. The plant will make methane from the waste by using microorganisms to break down the food in a two-stage digestion process over a few days.

Because the food waste being fermented on any given day can be more or less acidic depending on what was tossed out, the pH levels have to be constantly monitored in order for the microorganisms to best do their thing. The waste is held in several tanks that feature a management system that monitors many parameters, including pH level. The software then calculates how many liters of which waste should be mixed together to feed to the microorganisms.

The plant produces about two-thirds methane and one-third carbon dioxide from the process, but nothing goes unused:  the filtrate water which contains nitrogen and phosphorous, and the carbon dioxide produced from the fermentation are both used to cultivate algae for another project, while the sludge left behind from the fermentation is sent to other institutes that are capable of making methane from it.

The pilot project has been funded by the German Federal Ministry of Education and Research and has partnerships with energy company Energie Baden-Württemberg, which is processing the biogas, and with Daimler, which is supplying natural gas-converted vehicles to run on the fuel.

via Gizmag

In the past couple of years, we've seen many, many tests being carried out by numerous different airlines and agencies to study the possibilities of using biofuel as an entire replacement for or as a blend with conventional jet fuel. But biofuels as a replacement for petroleum-based jet fuel may not be the ideal solution.

Biofuels are better than straight petroleum-based products, but there are drawbacks to biofuels, as well. Dedicating cropland to grow fuel crops can cut down on the available land and farming resources for food production. There are arguments against algae-based fuels, as well. They don't compete with food for farmland, but the industrial infrastructure needed to produce algae-based fuel at scale is a daunting prospect.

Of course, conversion to any new material is a daunting prospect. The development of new technologies will eventually be necessary, one way or another. To continue to research alternatives and to find the best mix of feedstock for alternative fuels is importatnt not only for aviation, but for all energy technologies.

Virgin Atlantic, which is one of the many airlines to have tested biofuels, is now exploring a jet fuel replacement that, rather than using bio materials as feedstock, is derrived from waste industrial gas from steel production.  But if that relies on petroleum fuels as the original feedstock, then the long term viability of that process is also questionable.

via: Treehugger and Guardian