Power Plant Converts Fruit and Veggie Waste Into Natural Gas For Cars 118
Zothecula writes "Some readers might remember the Mr. Fusion unit in Back to the Future that Doc Brown fills with household garbage, including a banana peel and some beer, to power the iconic time-traveling DeLorean. While we're still some way from such direct means of running our cars on table scraps, researchers at Fraunhofer have developed a pilot plant that ferments the waste from wholesale fruit and veg markets, cafeterias and canteens to make methane, which can be used to power vehicles."
Re:Good idea, expand it to cover more fule sources (Score:5, Informative)
Unfortunately the chemicals that industrial agriculture uses interferes with the nutrient cycle that you're thinking of. Because everything other than the plant of interest is treated as something to be killed off with insecticides, fungicides, etc., the soil microbes are killed off, and the survivors are in an imbalanced ecological state which means that they're more likely to act in ways not helpful to the crop. It all leads back to dependency on oil-based fertilizers and pesticides while the soil is little more than a medium to hold the plant upright.
Otherwise, your solution would fit right in.
Re:Expand it to cover more fuel sources. (Score:5, Informative)
I live in the middle of an agriINDUSTRY area. Most of the agricultural waste is left to rot in the fields. To bring it to some place where it could be processed into fuel would consume fuel. Further, much of this waste is recycled into the soil by insects, worms, fungi and bacteria to become fertilizer for the next crop (lest the soil become exhausted.)
It's a neat idea, but you can use any hydrocarbon waste for this process - cardboard, paper or wood scraps.
Re:Expand it to cover more fuel sources. (Score:5, Informative)
Actually high cellulose content products don't work much at all. You need a high nitrogen content material (poop is the preferred material, ideally bird stuff because it contains the urine as well). There is a particular ratio of carbon to nitrogen that works best and by using various combinations of poop and different vegetable matter you get a mixture that gives the most methane and the least CO2. Vegetable leaf matter by itself will work, slowly, but produces a much higher CO2 to methane ratio so is not very useful for combustion. I assume that actual fruit and vegatables have higher nitrogen content than the leaves.
I built a few methane digesters in the 70's and I can tell you that it's not as easy as it sounds to actually produce useful amounts of methane. There is a lot of continuous mixing that has to happen or thick viscous mats form and keep things from working right. This consumes energy. You also can't really compress methane much without using more energy to compress it than you get out of it.
Of course if it's armageddon and you have lots of pig poop & crazy midgets to run things, this could actually work.
Re:UGH! Wrong Direction! (Score:4, Informative)
Carbon from renewable sources moves in a cycle. The carbon dioxide that is released by burning plants is absorbed by growing plants. Carbon, being an element, can't be created or destroyed except in nuclear reactions (something plants aren't capable of doing), so there can be no net carbon release from renewable processes. The reason why fossil fuels contribute to carbon dioxide release is because fossil fuels represent stored carbon over millions of years, from an epoch when carbon dioxide was more prevalent in our atmosphere.