Farmland near Keynsham, England Ollie Phipps/Flickr

By spring 2017, the town of Keynsham could get up to 80 percent of its electricity from food waste alone

The future of green energy production might be in that bag of slimy kale in the back of your refrigerator. That’s the promise of a new power plant being built in a small U.K. town. The plant, now under construction in Keynsham, a town of 16,000 residents between Bath and Bristol, will use anaerobic digestion to generate electricity from food waste. The plan is to make enough of it to supply 80 percent of the town’s needs.

Plants like these aren’t in themselves a new idea, of course. Anaerobic digestion of sewage is common across the world. Several European countries, notably Germany, have also invested in power plants run partly on food waste, whose energy yield is generally higher than that for sewage slurry. What is potentially groundbreaking is that Keynsham’s plant, which is being built by the company Resourceful Earth, aims to be the first in a national network of small waste recycling/power production facilities designed to service individual communities. Instead of shipping expensively extracted fuels to large centralized power plants and then transmitting that electricity across long distances, this scaled-down approach uses a resource that’s locally abundant—food waste from nearby residents—and distributes the power it creates within the same area.

This so-called distributed generation model is generally more efficient and resilient than the more-common centralized generation power network, especially if, as in Keynsham, the plants consume renewable sources of energy. This combination of waste management and power generation could spin up a virtuous cycle of reduced carbon emissions, smaller landfills, less power transmission infrastructure, and cheaper electricity for residents. With a construction price of £8 million ($9.8 million), the plant isn’t even that expensive.

The technology itself is quite simple. Locally sourced food waste is digested by bacteria in an airless environment, producing methane. This methane is then captured and burned to produce electricity, a process that will begin at Keynsham in spring 2017. Prices haven’t yet been fixed or published, but the hope is that the electricity will be offered at a considerably lower rate than conventionally sourced electricity. The residue left over after the methane has been extracted—called digestate—can then be pasteurized and used as a fertilizer.

The idea of burning gas being a green solution might seem counterintuitive, but converting food to biogas via digestion is actually climate-friendlier than composting it: As it biodegrades, compost (which Resourceful Earth already makes) emits methane, which can trap a lot more heat in the atmosphere than carbon dioxide. Composting doesn’t produce extra methane: The gas would have been released anyway as the waste rotted. Capturing it and burning it releases no more carbon dioxide than the plants absorbed while growing, but methane emissions are completely eliminated.

It’s an elegant solution, but only a partial one: Even if the U.K. waste-food mountain remained as high as it is currently—around 15 million tons a year—and all this waste was used for anaerobic digestion, the total power produced would only be enough to provide power for 350,000 households. That sounds impressive, but wouldn’t go far in a country of 26.7 million households.

Still, Resourceful Earth’s plan to synchronize recycling and power production is worth watching: Rolled out nationwide, it might help the U.K. hit its carbon emissions targets—a reduction of 80 percent from 1990 levels by 2050 —without boosting energy costs.

About the Author

Most Popular

  1. A man and a woman shop at a modern kiosk by a beach in a vintage photo.
    Design

    Why Everyday Architecture Deserves Respect

    The places where we enact our daily lives are not grand design statements, yet they have an underrated charm and even nobility.

  2. A chef prepares food at a restaurant in Beijing, China.
    Life

    What Restaurant Reviews Reveal About Cities

    Where official census data is sparse, MIT researchers find that restaurant review websites can offer similar demographic and economic information.

  3. A NASA rendering of a moon base with lunar rover from 1986.
    Life

    We Were Promised Moon Cities

    It’s been 50 years since Apollo 11 put humans on the surface of the moon. Why didn’t we stay and build a more permanent lunar base? Lots of reasons.

  4. The legs of a crash-test dummy.
    Transportation

    A Clue to the Reason for Women’s Pervasive Car-Safety Problem

    Crash-test dummies are typically models of an average man. Women are 73 percent more likely to be injured in a car accident. These things are probably connected.

  5. Environment

    How ‘Corn Sweat’ Makes Summer Days More Humid

    It’s a real phenomenon, and it’s making the hot weather muggier in the American Midwest.

×