Let Them Eat Cake: Microbes Turn Food Scraps Into Energy

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It's no big secret that a lot of food gets wasted every year. Millions of tons of food (if not more), not only from leftovers but also from food products that go unsold or suffer weather-related casualties, are unceremoniously dumped into huge landfills where they are left to rot. Ever wondered what could be done with this excess food?

Ruihong Zhang, a bioengineer from UC Davis, may have just found a possible solution to this vexing problem: a bioreactor filled with microbes that feast on solids, including foods and yard waste, and convert them into biogas, principally methane and hydrogen. This natural gas can then be burned to produce electricity or compressed into a fuel to power vehicles. A large-scale test unit installed at UC Davis has already converted over eight tons of waste into 300,000 to 600,000 liters of biogas a day, which is sufficient to power about 80 homes. If implemented on a wider scale, it could effectively help us dispose of all those large piles of landfill waste in an energy-conscious fashion. Not surprisingly, the project has already attracted its fair share of attention from several food producers and municipalities, and Zhang has formed a partnership with startup Onsight Biosystems, to commercialize it.

Still, since relatively little is known about how the bacteria living within the reactors produce natural gas, Zhang belies much could be learned from sequencing their genomes, a process that could also provide insight on how to ameliorate the bioreactors' productivity.

"Sequencing these organisms will give us a better idea of who the players are so we can better control the conditions or improve the design to further improve conversion of waste into biogas," said Zhang.

The Joint Genome Institute, which plans on taking up this challenge, hopes to determine which types of genes predominate in these microbes and how their communities change and adapt to different temperatures and acidities, which can significantly affect the performance of the bioreactors. "We want to compare what kind of microbes are there at different conditions and try to figure out why one [set of conditions] works better than the other," says Martin Wu, a geneticist at UC Davis who will work with Zhang on this new project.

While it remains to be seen whether these bacteria will prove the end-all solution to eliminating all of our landfill waste (factors such as cost, ease of construction, etc are not yet fully fleshed out), Zhang's bioreactor system is a promising new technology that has the additional benefit of delivering a renewable source of energy.

Via ::From Leftovers to Energy (magazine)

See also: ::China Moves to Ban Food Crops in Ethanol Production, ::Turning Grease to Fuel, and Despair to Hope, ::South Africa’s Biofuels Strategy. Food or Fuel?, ::Beer Waste to Energy: Anheuser-Busch's BERS System