Fuel Your Car With Garbage: Back to the Future?

In news reports here, here, and here, we learn that microbiologists are devising fuel cells that could potentially run on garbage--reminding one of the "Mr. Fusion" garbage burning DeLorean from the movie. From the Eurekalert newsrelease:

"Microbial fuel cells show promise for conversion of organic wastes and renewable biomass to electricity, but further optimization is required for most applications," says Derek Lovley of the University of Massachusetts in Amherst. Earlier this month, Lovley announced at a meeting that he and his colleagues were able to achieve a 10-fold increase in electrical output by allowing the bacteria in microbial fuel cells to grow on biofilms on the electrodes of a fuel cell.

This week, Gemma Reguera, a researcher in Lovley's lab will present data identifying for the first time how these bacteria are able to transfer electrons through the biofilms to the electrodes.

"Cells at a distance from the anode remained viable with no decrease in the efficiency of current production as the thickness of the biofilm increased. These results are surprising because Geobacter bacteria do not produce soluble molecules or 'shuttles' that could diffuse through the biofilm and transfer electrons from cells onto the anode," says Reguera.

She and her colleagues discovered that the bacteria produce conductive protein filaments, or pili 'nanowires,' to transfer electrons. The finding that pili can extend the distance over which electrons can be transferred suggests additional avenues for genetically engineering the bacteria to further enhance power production.

In further developments using bacteria to produce energy, Researchers from the Universidad Nacional Autonoma de Mexico announce that they have genetically engineered the bacterium Bacillus subtilis to directly ferment glucose sugar to ethanol with a high (86%) yield. This is the first step in a quest to develop bacteria that can breakdown and ferment cellulose biomass directly to ethanol.

"Currently ethanol is produced primarily from sugarcane or cornstarch, but much more biomass in the whole plant, including stems and leaves, can be converted to ethanol using clean technology," says Aida-Romero Garcia, one of the researchers on the study. The next step is to engineer the bacteria to produce the enzymes, known as cellulases, to break the stems and leaves down into the simple carbohydrates for fermentation.

Bacteria can not only produce alternative fuels, but could also aid in oil production by boosting output of existing wells. Michael McInerney and his colleagues at the University of Oklahoma will present research demonstrating the technical feasibility of using detergent-producing microorganisms to recover entrapped oil from oil reservoirs.

"Our approach is to use microorganisms that make detergent-like molecules (biosurfactants) to clean oil off of rock surfaces and mobilize oil stuck in small cavities. However, up till now, it is not clear whether microorganisms injected into an oil reservoir will be active and whether they will make enough biosurfactant to mobilize entrapped oil," says McInerney.

He and his colleagues were able to inoculate an oil reservoir with specific strains of bacteria and have these bacteria make biosurfactants in amounts needed for substantial oil recovery. Source.

In other science news, using carbon nanotubes to create nanotech membrane filters promises to achieve chemical separations at lower costs, including desalination of saltwater, air purification, and chemical separation for industrial processes and chemical refining.

A nanotube membrane on a silicon chip the size of a quarter may offer a cheaper way to remove salt from water. Researchers at Lawrence Livermore National Laboratory have created a membrane made of carbon nanotubes and silicon that may offer, among many possible applications, a less expensive desalination.

The nanotubes, special molecules made of carbon atoms in a unique arrangement, are hollow and more than 50,000 times thinner than a human hair. Billions of these tubes act as the pores in the membrane. The super smooth inside of the nanotubes allow liquids and gases to rapidly flow through, while the tiny pore size can block larger molecules. This previously unobserved phenomenon opens a vast array of possible applications.

The team was able to measure flows of liquids and gases by making a membrane on a silicon chip with carbon nanotube pores making up the holes of the membrane. The membrane is created by filling the gaps between aligned carbon nanotubes with a ceramic matrix material. The pores are so small that only six water molecules could fit across their diameter.

“The gas and water flows that we measured are 100 to 10,000 times faster than what classical models predict,” said Olgica Bakajin, the Livermore scientist who led the research. “This is like having a garden hose that can deliver as much water in the same amount of time as a fire hose that is ten times larger.” Source.

I am always looking for technologies that could be used for remote habitats--including undersea, outer space, mid-ocean, or other isolated habitats--to produce energy, clean water, food, and other necessities from unconventional materials, including recycled organics. Many of the new microbiological and nanotechnological technologies certainly suggest possible approaches to providing such functions, and more.