Food as Fuel?
In the News
September 23, 2012
At the end of Back to the Future, Doc Brown tells Marty McFly that he has converted the DeLorean time machine from a plutonium-based gas-guzzler to an Earth-friendly vehicle deriving power from simple household garbage. In 1985, this idea seemed at once both fictional and revolutionary. Today, however, alternative fuels made from food are a bona fide reality and could one day become the norm – rather than the exception.
There are companies that are developing ways to make gasoline components from algae, diesel fuel from animal fat or vegetable oil, and car fuel from – you guessed it – simple household garbage. And now, even spinach is getting its due.
Recently, researchers at Vanderbilt University figured out a way to create more powerful solar cells from Popeye’s favorite food – spinach. By mixing the protein in spinach with silicon, they were able to produce a “biohybrid” solar cell able to generate more electrical current and voltage than any similar biohybrid solar cell created previously.
Dr. David Cliffel, Associate Professor of Chemistry at Vanderbilt University, explains that in their biohybrid cell, the light is absorbed by the photosynthetic protein. This light energy moves an electron from one end of the protein to the other end, creating a photocurrent. The photocurrent is then collected by the underlying electrode and a redox mediator. In this particular experiment, they changed the underlying electrode from gold to silicon and found a significant increase in photocurrent. But why use spinach?
“Spinach has been used for the ability to isolate the photosynthetic protein complexes like photosystem I easily for more than 30 years,” says Cliffel. “Photosystem I and Photosystem II are responsible for the ability of plants to harness sunlight in higher order plants. A small number of researchers have been working for many years to find ways to incorporate these proteins in artificial energy conversion systems, and our research is the newest finding in this field by taking advantage of our expertise in protein electrochemistry."
Cliffel says that spinach isn’t the only plant that would work in this arena, and they are currently pursuing other plants. The future of these studies, he says, may be able to someday achieve the high efficiency of photoconversion possible within the protein to a complete artificial device. Another benefit is that this energy conversion uses common, non-toxic elements without the need for rare, expensive, or toxic elements.
“The ability to use the common techniques of molecular biology to improve our ability to use photosystems in artificial devices holds promise for increasing the absorption spectra of these devices to yield higher conversion efficiencies of sunlight to generate photoelectrochemical energy,” says Cliffel.
These methods, adds Cliffel, could lead to co-operation with farmers and others in the food industry with expertise in growing experimental plants. In their case, they used relatively little amounts of the spinach plant, and it can last for nine months or more. Cliffel thinks biomass techniques might be useful for food waste too.
Another food fuel making headlines is vegetable oil. Craig Reece, owner of the U.S.-based PlantDrive.com, associated with the Canadian-based PlantDrive.ca, a company that provides high quality kits and components for the conversion of diesel engines to use 100% vegetable oil as fuel, says that using vegetable oil as an alternative fuel is a cost effective and smart way to produce renewable energy. Plant oil fuels used to replace diesel fuel use very little energy in their production as fuel. And most importantly, says Reece, we’re living in a time where we are using up the finite amount of conventional fuel that remains on this planet, so alternative fuels are more important than ever.
“Diesel fuel made from vegetable oil is renewable – the oilseed plant, when grown, absorbs the CO2 emitted by the oil from the seed when it's burned as fuel,” says Reece.
Also, the carbon footprint impact of renewable fuels is lower than newly created conventional fuels. Reece says that in the case of waste vegetable oil (WVO), the carbon inputs (chemical fertilizers, tractor fuel, transportation costs) needed to produce the oilseed crop were already there for its primary use as cooking oil, and when the used fryer oil is re-used as a fuel, none of these carbon inputs are "new.” WVO therefore has the smallest carbon footprint of any fuel.
“If a farm uses organic, non-petroleum-based fertilizers or manure and also uses plant oils as tractor fuel, and then transports the crop to the oilseed press using trucks fueled by plant oil, they can even further reduce the carbon footprint of the resulting fuel,” says Reece.
He adds, “We need to remember that petroleum fuels are not renewable – we're mining compressed prehistoric swamps that we're no longer creating, and when the fuel produced by these ancient underground swamps is gone, it's gone forever.”