News / Science & Technology

    Microbes Produce Electricity from Sewage

    A microbes clings to a carbon filament, serving as an efficient electrical conductor. (Xing Xie, Stanford Engineering)
    A microbes clings to a carbon filament, serving as an efficient electrical conductor. (Xing Xie, Stanford Engineering)

    Related Articles

    Man-Made Earthquakes on the Rise

    In the US, there were more than 300 earthquakes above magnitude 3.0 from 2010 to 2012

    Hydrogen Fuel Closer to Reality

    Commercialization of such a solar-thermal reactor is likely years away
    VOA News
    Researchers have devised a way to generate electricity using raw sewage and special bacteria.

    Engineers at Stanford University call the invention a “microbial battery” and hope one day the technology will be suitable for use at sewage treatment plants.

    For now, the prototype is about the size of a D-cell battery and looks like a “chemistry experiment with two electrodes, one positive, the other negative, plunged into a bottle of wastewater.”

    Engineers at Stanford University have extracted electricity from raw sewage. (Xing Xie, Stanford Engineering)Engineers at Stanford University have extracted electricity from raw sewage. (Xing Xie, Stanford Engineering)
    x
    Engineers at Stanford University have extracted electricity from raw sewage. (Xing Xie, Stanford Engineering)
    Engineers at Stanford University have extracted electricity from raw sewage. (Xing Xie, Stanford Engineering)
    Inside that murky vial, attached to the negative electrode like barnacles to a ship's hull, an unusual type of bacteria feast on particles of organic waste and produce electricity that is captured by the battery's positive electrode.

    "We call it fishing for electrons," said Craig Criddle, a professor in the department of civil and environmental engineering.

    The electrons come from exoelectrogenic microbes – organisms that evolved in airless environments and developed the ability to react with oxide minerals, rather than breathe oxygen as we do, to convert organic nutrients into biological fuel.

    For years, scientists have tried to tap the energy produced by these creatures, but until now it has proved challenging.

    The Stanford researchers approach was new.

    At the battery's negative electrode, colonies of wired microbes cling to carbon filaments that serve as efficient electrical conductors.

    "You can see that the microbes make nanowires to dump off their excess electrons," Criddle said. To put the images into perspective, about 100 of these microbes could fit, side by side, in the width of a human hair.

    As these microbes ingest organic matter and convert it into biological fuel, their excess electrons flow into the carbon filaments, and across to the positive electrode, which is made of silver oxide, a material that attracts electrons.

    The electrons flowing to the positive node gradually reduce the silver oxide to silver, storing the spare electrons in the process.

    According to Xing Xie, an interdisciplinary researcher, after a day or so the positive electrode has absorbed a full load of electrons and has largely been converted into silver.

    At that point it is removed from the battery and re-oxidized back to silver oxide, releasing the stored electrons.

    The battery, scientists say, is about 30 percent efficient in extracting the energy from waste water. While that may sound small, it is roughly the same efficiency as the best commercially available solar cells.

    And while waste water will never offer the same potential solar energy could, the Stanford researchers say it’s worth pursuing because at the very least, it could offset some of the electricity used to treat sewage, or about  3 percent of the total electrical load in developed nations.

    One drawback with the battery is the expense of silver.

    "We demonstrated the principle using silver oxide, but silver is too expensive for use at large scale," said Yi Cui, an associate professor of materials science and engineering.

    "Though the search is underway for a more practical material, finding a substitute will take time."

    You May Like

    Syrian Rebel Realignment Likely as al-Qaida Leader Blesses Split

    Jihadist group Jabhat al-Nusra splits from al-Qaida in what observers dub a ‘deception and denial’ exercise

    New India Child Labor Law Could Make Children More Vulnerable

    Concerns that allowing children to work in family enterprises will push more to work

    What Take-out Food Reveals About American History

    Carry-out food explains a lot about the changes taking place in society, so here's the deal with pizza, Chinese food and what racism has to do with taking food to go

    This forum has been closed.
    Comment Sorting
    Comments
         
    by: Christian from: Colombia
    September 17, 2013 8:51 PM
    That´s one of the most smart and necessary inventions that human being have done until now because in this moment we just need to protect the environment all people even in Colombia are in emergency about the environment without oxygen it´s imposible to survive.

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Uganda Unveils its First Solar-powered Busi
    X
    July 28, 2016 4:16 AM
    A solar-powered bus described by its Ugandan makers as the first in Africa has made its public debut. Kiira Motors' electric bus, Kayoola, displayed recently at a stadium in Uganda's capital. From Kampala, Maurice Magorane filed this report narrated by Salem Solomon.
    Video

    Video Uganda Unveils its First Solar-powered Bus

    A solar-powered bus described by its Ugandan makers as the first in Africa has made its public debut. Kiira Motors' electric bus, Kayoola, displayed recently at a stadium in Uganda's capital. From Kampala, Maurice Magorane filed this report narrated by Salem Solomon.
    Video

    Video Silicon Valley: More Than A Place, It's a Culture

    Silicon Valley is a technology powerhouse and a place that companies such as Google, Facebook and Apple call home. It is a region in northern California that stretches from San Francisco to San Jose. But, more than that, it's known for its startup culture. VOA's Elizabeth Lee went inside one company to find out what it's like to work in a startup.
    Video

    Video Immigrant Delegate Marvels at Democratic Process

    It’s been a bitter and divisive election season – but first time Indian-American delegate Dr. Shashi Gupta headed to the Democratic National Convention with a sense of hope. VOA’s Katherine Gypson followed this immigrant with the love of U.S. politics all the way to Philadelphia.
    Video

    Video Philadelphia Uses DNC Spotlight to Profile Historic Role in Founding of United States

    The slogan of the Democratic National Convention now underway in Philadelphia is “Let’s Make History Again” which recognizes the role the city played in the foundation of the United States in the 18th century. As VOA’s Kane Farabaugh reports, local institutions are opening their doors in an effort to capitalize on the convention spotlight to draw visitors, and to offer more than just a history lesson.
    Video

    Video A Life of Fighting Back: Hillary Clinton Shatters Glass Ceiling

    Hillary Clinton made history Thursday, overcoming personal and political setbacks to become the first woman to win the presidential nomination of a major U.S. political party. If she wins in November, she will go from “first lady” to U.S. Senator from New York, to Secretary of State, to “Madam President.” Polls show Clinton is both beloved and despised. White House Correspondent Cindy Saine takes a look at the life of the woman both supporters and detractors agree is a fighter for the ages.
    Video

    Video Dutch Entrepreneurs Turn Rainwater Into Beer

    June has been recorded as one of the wettest months in more than a century in many parts of Europe. To a group of entrepreneurs in Amsterdam the rain came as a blessing, as they used the extra water to brew beer. Serginho Roosblad has more to the story.
    Video

    Video First Time Delegate’s First Day Frustrations

    With thousands of people filling the streets of Philadelphia, Pennsylvania for the 2016 Democratic National Convention, VOA’s Kane Farabaugh narrowed in on one delegate as she made her first trip to a national party convention. It was a day that was anything but routine for this United States military veteran.
    Video

    Video Commerce Thrives on US-Mexico Border

    At the Democratic Convention in Philadelphia this week, the party’s presumptive presidential nominee, Hillary Clinton, is expected to attack proposals made by her opponent, Republican presidential nominee Donald Trump, to build a wall along the U.S.-Mexico border. Last Friday, President Barack Obama hosted his Mexican counterpart, President Enrique Peña Nieto, to underscore the good relations between the two countries. VOA’s Greg Flakus reports from Tucson.
    Video

    Video Film Helps Save Ethiopian Children Thought to be Cursed

    'Omo Child' looks at effort of African man to stop killings of ‘mingi’ children
    Video

    Video London’s Financial Crown at Risk as Rivals Eye Brexit Opportunities

    By most measures, London rivals New York as the only true global financial center. But Britain’s vote to leave the European Union – so-called ‘Brexit’ – means the city could lose its right to sell services tariff-free across the bloc, risking its position as Europe’s financial headquarters. Already some banks have said they may shift operations to the mainland. Henry Ridgwell reports from London.
    Video

    Video Recycling Lifeline for Lebanon’s Last Glassblowers

    In a small Lebanese coastal town, one family is preserving a craft that stretches back millennia. The art of glass blowing was developed by Phoenicians in the region, and the Khalifehs say they are the only ones keeping the skill alive in Lebanon. But despite teaming up with an eco-entrepreneur and receiving an unexpected boost from the country’s recent trash crisis the future remains uncertain. John Owens reports from Sarafand.
    Video

    Video Migrants Continue to Risk Lives Crossing US Border from Mexico

    In his speech Thursday before the Republican National Convention, the party’s presidential candidate, Donald Trump, reiterated his proposal to build a wall along the U.S.-Mexico border if elected. Polls show a large percentage of Americans support better control of the nation's southwestern border, but as VOA’s Greg Flakus reports from the border town of Nogales in the Mexican state of Sonora, the situation faced by people trying to cross the border is already daunting.

    Special Report

    Adrift The Invisible African Diaspora