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Page added on February 10, 2012
Pilot plant converts fruit and veggie waste into natural gas for cars
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.
Given the rising oil prices in recent years, many drivers have been converting their cars to run on natural gas. But like oil, natural gas is a fossil fuel with limited reserves whose price has also risen in recent years and is likely to continue to do so. Fraunhofer’s development provides an alternative way to obtain natural gas, not from Earth’s reserves, but from fruit and vegetable waste.
The pilot plant is part of the ETAMAX project and has been constructed adjacent to Stuttgart’s wholesale market. Due to begin operation in the next few months, the plant generates methane by using various microorganisms that act on the food waste in a two-stage digestion process that lasts just a few days.
“The waste contains a lot of water and has a very low lignocellulose content, so it’s highly suitable for rapid fermentation,” says Dr.-Ing. Ursula Schließmann, head of department at the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB).
Because the microorganisms require constant environmental conditions to function and the waste can vary in composition every day – some days it will contain a high proportion of acidic citrus fruits, on others it might have more cherries, plums or lettuce – the researchers must adjust the pH value through substrate management.
“We hold the waste in several storage tanks, where a number of parameters are automatically calculated – including the pH value. The specially designed management system determines exactly how many liters of waste from which containers should be mixed together and fed to the microorganisms,” explains Schließmann.
Enhancing the environmental benefits of the plant, everything the plant generates can be utilized, including the liquid filtrate and the sludgy residue that can’t be broken down any further by the microorganisms. The filtrate water, which contains nitrogen and phosphorous, is used as a culture medium for the cultivation of algae at a second sub-project in Reutlingen. And while two thirds of the biogas produced at the Stuttgart plant is methane, around 30 percent is carbon dioxide, which is also used to cultivate the algae. Meanwhile, the remaining sludgy fermentation residue is delivered to the Paul Scherrer Institute in Switzerland and the Karlsruhe Institute of Technology, where it is also converted into methane.
In addition to Fraunhofer, the ETAMAX project also involves the participation of energy company Energie Baden-Württemberg (EnBW), which uses membranes to process the generated biogas, and Daimler, which supplies a number of experimental vehicles designed to run on natural gas. The German Federal Ministry of Education and Research (BMBF) has funded the five-year project to the tune of six million euros (approx. US$7.97 million). If the various components mesh together as hoped, similar plants could be built where large quantities of organic waste can be found.
Source: Fraunhofer
6 Comments on "Pilot plant converts fruit and veggie waste into natural gas for cars"
Kenz300 on Fri, 10th Feb 2012 5:27 pm
Every landfill can now be converted to produce biofuels, energy (methane) and raw materials for new products. It is time to move to a more sustainable model. The world produces a lot of trash every day. It is time to put that trash to good use.
eastbay on Fri, 10th Feb 2012 7:36 pm
This is pathetic! It’s not waste!
It’s nutritious compost material containing scarce nutrients that should be returned to the soil, not burned.
This contraption is just another fine example of humans looking around to discover what else can be burned to keep a small fraction of our hugely energy wasteful personal transport on the road.
DC on Fri, 10th Feb 2012 8:27 pm
Its all about the cars isnt it. Got to keep them running, no matter what it takes. I wonder what the energy balance for this boondoggle is? How many tons, yes tons of plant matter will it take to fill the tank of one mobile-trash bin?
http://www.futurepundit.com/archives/001744.html
Burning trash for low-grade heat energy is no answer either. It runs into 2 basic problems. One, the energy liberated from the trash is going to be pretty low, far less than the energy it took to produce, ship, break the trash, then go thro all the steps to collect it for burning. For food waste the problem is even worse. Industrial food production is criminally wasteful in terms of energy. Taking 10 units\energy to produce 1 unit of food. What % of food ends up as waste. We fat lazt N.A. apparently like to thro out around 50% or so of the total food we produce. so now we have .5 units of food to left over, with a production cost of 20 energy units. Then someone expends a LOT of fossil-fuel energy to run out and collect all that food waste for delivery to a central miracle waste food zapper. Of course, nowhere near the 50% of the 1 unit of food we thro out will ever get collected. Be lucky if 25% of it ever saw a zapper. so now were down to .125% of total food waste(optimisically!) that might end up being made into ‘fuell. Minus the energy required for the process itself. Again. be lucky if its 50% efficent, that is too say, over 1/2 the energy produced at end has to go run the process itself.
Now were down to .00625% or so. Again cant forget it took 10 units of energy inputs intially to go that tiny .00625 were now gonna try to convert back into fuel…whew. Basically, long story short, we ran into a negative energy balance long before we get this point. In fact, it was hopeless at the collection stage. Best idea of all. Start a compost pile and use the compost in a community or sell to local farms. Fuel from scarps..another moronic idea to profit from the decline of the age of oil. My mumbers may not be perfect, but, I think It not hard to see this idea is pretty foolish.
The other issue is, to set up a waste fo energy system like this in the 1st place, requires a criminally wasteful society in the 1st place. We are all that, but the end of the oil age, will also mean the end of the constant stream of trash we produce. And no one in a oil-constrained world will be throwing out 50% of there net food production just because that apple or potato is not the color or shape pleaseing to consumers…
BillT on Sat, 11th Feb 2012 12:24 am
EROEI…this idea is dead in the water.
Not only is it impractical, but the largest landfill would not last a year if real quantities of energy were to be produced. Not to mention all of the toxic chemicals released into the air in the process. Get used to the idea of NOT having a fuel powered personal vehicle.
John Baldwin on Sat, 11th Feb 2012 9:25 am
Crazy waste of energy and effort, biomethane is the future:
http://www.bogaspartner.de
Make bimethane, inject to grid, take it out at CNG filling station.
BillT on Sat, 11th Feb 2012 9:31 am
John…would the fact that methane would have to be trucked to the stations, just like gasoline is today, make a difference in your idea that this would work? There is no ‘grid’ to take it anywhere. The natural gas grid we have today took decades and billions of dollars to install. A new grid is impossible at this point.