Microbes Convert Wastewater into Useable Electricity

Millions of tiny microbes infest the water carrying the detritus of human life and society. Some of them steadily break down the organic material in waste streams and produce electrons in the process. By harvesting these electrons, scientists have created microbial fuel cells. New research shows how such biological power plants can be stacked to create usable current.

Willy Verstraete and his colleagues at Ghent University in Belgium tested the fuel cells in an array of configurations: in a series, in parallel and individually. Over the course of more than 200 days, the researchers fed the microbes on a diet of anaerobic and aerobic sludge, as well as hospital and potato processing factory wastewater. By the end of the experimental time frame, short-term power densities--a measure of power produced per unit of mass--of the fuel cells had tripled. The team also found that the parallel stack produced electric charge most efficiently, consistently creating stronger current.

The scientists main discovery, however, had to do with the co-evolution of the electrochemical properties of the fuel cell and the actual microbial community. At the start of the experiment, the tiny power plants relied on a diverse community of proteobacteria, including several species of Geobacter and Shewanella and produced power somewhat inefficiently. But by the end of the experiment--when performance was at its peak--one species, Brevibacillus agri, made up the majority of the electron-producing microbes.

This microbial evolution calls for further research into the electron-producing properties of various species and their interaction, the authors write. A paper presenting the findings will be published in the May 15 issue of Environmental Science & Technology. --David Biello

Scientists find Antarctic ice shrank significantly

WASHINGTON (Reuters) - The Antarctic ice sheet shrank significantly during the past three years, according to the findings of a NASA study released on Thursday.

Using data from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE), scientists concluded that Antarctica's ice sheet decreased by about 152 cubic kilometers annually from April 2002 to August 2005.

The estimated loss was enough to raise global sea level about 1.2 millimeters (0.04724 inch) during the study period or about 13 percent of the overall observed sea level rise for the same period, according to the study conducted by researchers at the University of Colorado, Boulder.

That is about how much water the United States consumes in three months and represents a change of about 0.4 millimeter (0.01575 inch) per year to global sea level rise, the study concluded.

Most of the mass loss came from the West Antarctic ice sheet, the study said.

"Antarctica is Earth's largest reservoir of fresh water," researcher Isabella Velicogna said.

"The GRACE mission is unique in its ability to measure mass changes directly for entire ice sheets and can determine how Earth's mass distribution changes over time," she said.

"Because ice sheets are a large source of uncertainties in projections of sea level change, this represents a very important step toward more accurate prediction," Velicogna said.

Measuring variations in Antarctica's ice sheet mass is difficult because of its size and complexity.

Twin GRACE satellites, which can track tiny changes in Earth's gravity field, monitored the entire Antarctic ice sheet as a whole.

© Reuters 2006. All Rights Reserved.

New water purification invention

Author: Erick Schonfeld

Date Published: 2006-02-19

San Francisco (Business 2.0) -

Dean Kamen, the engineer who invented the Segway, is puzzling over a new equation these days. An estimated 1.1 billion people in the world don't have access to clean drinking water, and an estimated 1.6 billion don't have electricity. Those figures add up to a big problem for the world—and an equally big opportunity for entrepreneurs.

To solve the problem, he's invented two devices, each about the size of a washing machine that can provide much-needed power and clean water in rural villages.

"Eighty percent of all the diseases you could name would be wiped out if you just gave people clean water," says Kamen. "The water purifier makes 1,000 liters of clean water a day, and we don't care what goes into it. And the power generator makes a kilowatt off of anything that burns."

Light in the darkness

Kamen is not alone in his quest. He's been joined by Iqbal Quadir, the founder of Grameen Phone, the largest cell phone company in Bangladesh. Last year, Quadir took prototypes of Kamen's power machines to two villages in his home country for a six-month field trial. That trial, which ended last September, sold Quadir on the technology.

So much so in fact that Quadir's startup, Cambridge, Mass.-based Emergence Energy, is negotiating with Kamen's Deka Research and Development to license the technology. Quadir then hopes to raise $30 million in venture capital to start producing the power machines. (With the exception of the Segway, which Kamen's own company sold, Kamen has typically licensed his inventions to others.)

The electric generator is powered by an easily-obtained local fuel: cow dung. Each machine continuously outputs a kilowatt of electricity. That may not sound like much, but it is enough to light 70 energy-efficient bulbs. As Kamen puts it, "If you judiciously use a kilowatt, each villager can have a nighttime."

A satellite picture of the earth at night shows swaths of darkness across Southeast Asia, the Middle East, and Africa. For the people living there, a simple light bulb would mean an extension of both their productivity and their leisure times.

Entrepreneurial power

The real invention here, though, may be the economic model that Kamen and Quadir hope to use to distribute the machines. It is fashioned after Grameen Phone's business, where village entrepreneurs (mostly women) are given micro-loans to purchase a cell phone and service. The women, in turn, charge other villagers to make calls.

"We have 200,000 rural entrepreneurs who are selling telephone services in their communities," notes Quadir. "The vision is to replicate that with electricity."

During the test in Bangladesh, Kamen's Stirling machines created three entrepreneurs in each village: one to run the machine and sell the electricity, one to collect dung from local farmers and sell it to the first entrepreneur, and a third to lease out light bulbs (and presumably, in the future, other appliances) to the villagers.

Kamen thinks the same approach can work with his water-cleaning machine, which he calls the Slingshot. While the Slingshot wasn't part of Quadir's trial in Bangladesh, Kamen thinks it can be distributed the same way. "In the 21st century, water will be delivered by an entrepreneur," he predicts.

The Slingshot works by taking in contaminated water – even raw sewage -- and separating out the clean water by vaporizing it. It then shoots the remaining sludge back out a plastic tube. Kamen thinks it could be paired with the power machine and run off the other machine's waste heat.

Compared to building big power and water plants, Kamen's approach has the virtue of simplicity. He even created an instruction sheet to go with each Slingshot. It contains one step: Just add water, any water. Step two might be: add an entrepreneur.

"Not required are engineers, pipelines, epidemiologists, or microbiologists," says Kamen. "You don't need any -ologists. You don't need any building permits, bribery, or bureaucracies."

The price of freedom

Still, even if some of the technical challenges have been solved ("I know the technology works and I'd fall on my sword to prove it," insists Kamen), the economic challenges still loom.

Kamen's goal is to produce machines that cost $1,000 to $2,000 each. That's a far cry from the $100,000 that each hand-machined prototype cost to build.

Quadir is going to try and see if the machines can be produced economically by a factory in Bangladesh. If the numbers work out, not only does he think that distributing them in a decentralized fashion will be good business -- he also thinks it will be good public policy. Instead of putting up a 500-megawatt power plant in a developing country, he argues, it would be much better to place 500,000 one-kilowatt power plants in villages all over the place, because then you would create 500,000 entrepreneurs.

"Isn't that better for democracy?" Quadir asks. "We see a shortage of democracy in the world, and we are surprised. If you strengthen the economic hands of people, you will foster real democracy."

Lights, water, freedom. Now that's entrepreneurial.

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New idea: Inject sea water to raise Venice

BEIJING, Nov. 23 -- A group of Italian engineers and geology experts said Monday they are considering injecting sea water under Venice to raise the waterlogged city 30 centimeters and rescue it from the tides and floods that bedevil it.

"It would allow Venice to regain ... nearly the same amount of centimeters by which it sank over the last 300 years," said Giuseppe Gambolati, the head of the project.

The US$117-million project entails digging 12 holes with a 30-centimeter diameter within a 9.6-kilometer area around the city of Venice, and to pump sea water into the ground, said Gambolati, an engineer and professor at the University of Padua.

The sea water is expected to make the sand that lies underneath expand, which combined with a topping of waterproof clay would eventually push up the soil, Gambolati said.

The project is still in its initial phase and it will have to be discussed and evaluated by various city, regional and state commissions before being approved.

Venice is threatened by water on several fronts. The city is sinking while the level of the Adriatic sea is rising and high tides are becoming more frequent, flooding into famed St. Mark's Square and prompting officials to set up raised plank walkways.

The decades-old debate on how to save Venice from water brought approval in 2003 of a vast project to build a flood barrier to ease the effect of high tides.

(Source: Shenzhen Daily/Agencies)