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

China’s Influence Grows With New Infrastructure Bank

Multibillion-dollar China-backed and BRICS-supported Asian Infrastructure Investment Bank seen as possible challenger to such lenders as IMF, World Bank More

Video Rabbi Hits Road to Heal Jewish-Muslim Relations in France

Rabbi Michel Serfaty makes the rounds in his friendship bus to encourage dialogue and break down barriers between the two groups More

Post-deal Iran Leaders Need 'Economic Momentum' to Solidify Power Base

Economists say deal could inject more than $100 billion into coffers - not enough to entirely rescue ailing economy - but maybe adequate to create 'economic momentum' More

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.
US Gay Marriage Ruling Yields Real-life Impacti
X
Michael Bowman
June 28, 2015 10:05 PM
Friday’s landmark Supreme Court decision legalizing same-sex marriage throughout the United States is an outcome few thought possible just years ago, and shows a nation that increasingly tolerates and even celebrates the hopes and aspirations of gay people. VOA’s Michael Bowman spoke to a same-sex couple that will benefit from the high court ruling, and to a Christian scholar who is apprehensive about its potential consequences for America’s faith community.
Video

Video US Gay Marriage Ruling Yields Real-life Impact

Friday’s landmark Supreme Court decision legalizing same-sex marriage throughout the United States is an outcome few thought possible just years ago, and shows a nation that increasingly tolerates and even celebrates the hopes and aspirations of gay people. VOA’s Michael Bowman spoke to a same-sex couple that will benefit from the high court ruling, and to a Christian scholar who is apprehensive about its potential consequences for America’s faith community.
Video

Video Syrians Flee IS Advance in Hasaka

The Syrian government said Monday it has taken back one of several districts in Hasaka overrun by Islamic State militants. But continued fighting elsewhere in the northern city has forced thousands of civilians from their homes. In this report narrated by Bill Rodgers, VOA Kurdish Service reporter Zana Omer describes the scene in Amouda, where some of the displaced are taking refuge.
Video

Video Rabbi Hits Road to Heal Jewish-Muslim Relations in France

France is on high alert after last week's terrorist attack near the city Lyon, just six months after deadly Paris shootings. The attack have added new tensions to relations between French Jews and Muslims. France’s Jewish and Muslim communities also share a common heritage, though, and as far as one French rabbi is concerned, they are destined to be friends. From the Paris suburb of La Courneuve, Lisa Bryant reports about Rabbi Michel Serfaty and his friendship bus.
Video

Video S. Korea Christians Protest Gay Rights Festival

The U.S. Supreme Court decision mandating marriage equality nationwide has energized gay rights supporters around the world. Gay rights remain a highly contentious issue in a key U.S. ally, South Korea, where police did a deft job Sunday of preventing potential clashes between Christian protesters and gay activists. Kurt Achin reports from Seoul.
Video

Video Saudi Leaks Expose ‘Checkbook Diplomacy’ In Battle With Iran

Saudi Arabia’s willingness to wield its oil money on the global diplomatic stage appears to have been laid bare, after the website WikiLeaks published tens of thousands of leaked cables from Riyadh’s Ministry of Foreign Affairs. VOA's Henry Ridgwell reports.
Video

Video Nubians in Kenya Face Land Challenges

East Africa's ethnic Nubians have a rich cultural history that dates back thousands of years, but in Kenya they are facing hardships, including the loss of lands they have lived on for generations. They say the government has reneged on its pledge to award them title deeds for the plots. VOA's Lenny Ruvaga reports.
Video

Video Syrian Refugees Return to Tal Abyad

Syrian refugees in Turkey confirm they left their hometown of Tal Abyad because of intense fighting and coalition airstrikes, not because Kurdish fighters were engaged in ethnic cleansing, as some Turkish officials charged. VOA Kurdish Service reporter Zana Omer, in Tal Abyad, finds that civilians coming back to the town agree, as we hear in this report narrated by Roger Wilkison.
Video

Video Military Experts Question New Russian Tank Capabilities

Russia has been showing off its new tank design – the Armata T-14. Designers claim it is 20 years ahead of current Western designs - and driving it feels like playing a computer game. But military analysts question those assertions, and warn the cost could be too heavy a burden for Russia’s struggling economy. Henry Ridgwell reports.
Video

Video In Kenya, Police Said to Shoot First, Ask Questions Later

An organization that documents torture and extrajudicial killings says Kenyan police were responsible for 1,252 shooting deaths in five cities, including Nairobi, between 2009 and 2014, representing 67 percent of all gun deaths in the areas reviewed. Gabe Joselow has more from Nairobi.
Video

Video In Syrian Crisis, Social Media Offer Small Comforts

Za’atari, a makeshift city in Jordan, may be the only Syrian refugee camp to tweet its activities, in an effort to keep donors motivated as the war in Syria intensifies and the humanitarian crisis deepens. Inside the camp, families say mobile phone applications help hold together families that are physically torn apart. VOA’s Heather Murdock reports.
Video

Video Chemical-Sniffing Technology Fights Australia's Graffiti Vandals

Cities and towns all over the world spend huge amounts of resources battling graffiti writers who deface buildings, public transport vehicles and even monuments. Authorities in Sydney, Australia, hope a new chemical-sniffing technology finally will stop vandals from scribbling on walls in the passenger areas of commuter trains. VOA’s George Putic has more.
Video

Video Cambodia Struggling to Curb Child Labor

Earlier this year a United Nations report found 10 percent of Cambodian children aged 7-14 are working – one of the highest rates in the region – and said one in four children in that age bracket are forced to quit school to help their families. Although the child labor rate has dropped over the past decade, Cambodia has a lot more to do – including keeping more children in school. Robert Carmichael reports for VOA from Phnom Penh.

VOA Blogs