America’s energy problems are quickly coming to a head. Fuel continues to increase in price and the hunt for renewable and clean options to power our homes, offices, factories and vehicles is on.Many swear by solar, wind or water energy, but a potentially industry-changing innovation is hiding under our feet. Literally.
Microorganisms like bacteria have been on this earth and lived in every different part of the planet for billions of years before humans came onto the scene. And they will be here long after we are too.
In microbial energy technologies, microorganisms make fuels out of raw organic materials, thereby converting the chemical energy in the biomass into chemical energy in the form of ethanol or hydrogen, for example.
In addition, microbes can convert solar energy to hydrogen.Those fuels are then burned to make electrical energy or, in the case of internal combustion engines, kinetic energy to power a car.
Most research on energy-producing microbes is done on naturally-occurring bacteria that researchers can grow in the lab. [SEE SOME OF THE MICROBE-BASED ENERGY PROJECTS IN THE WORKS]
By introducing new genes into these bacteria in the form of circular sections of DNA called plasmids, they can make the microbes express new proteins. If they can come up with the right kinds of proteins, they can hijack the bacteria’s natural mechanisms to make different compounds or live under different conditions.
One key to large-scale success in microbial bioenergy is managing the microbial community so that that the community delivers the desired bioenergy product reliably and at a high rate.
Photo: Stanford University
“Microbial communities are complex,” Stanford University researcher Alfred Spormann said in a statement. “For example, oxygen-consuming bacteria can help stabilise the community by preventing the build-up of oxygen gas, which methanogens cannot tolerate. Other microbes compete with methanogens for electrons. We want to identify the composition of different communities and see how they evolve together over time.”There are several problems that researchers can run into when trying to scale up their lab experiments: First, the bacteria need to survive when grown in tight spaces and in large amounts.
Getting them to grow in industrial-sized vats is difficult though. The bacteria need to have enough access to their energy source and nutrients, not to mention oxygen (or a lack of oxygen for some species, like the methanogens mentioned above). They also need to be kept at the right temperatures — too hot or too cold and their proteins won’t work efficiently. This is tough since in large amounts, bacteria and other living organisms tend to give off lots of heat.
Researchers also have to program the tiny cells to be able to make fuels in large amounts and in ways that researchers can isolate them to make them usable in an industrial setting. Third, this fuel needs to not kill the bacteria while they are being grown and harvested.
Researchers are still working with different bacteria that they can adapt to scale up to these conditions. One option, which would hold microbes that make hydrogen gas as a fuel, is seen above. Here’s how it would work, from the Biological Energy Interest Group at MIT:
Engineered microbes such as cyanobacteria or unicellular eukaryotic green-algae are grown in a photobioreactor consisting of closed, parallel transparent tubes. The medium in which they live is kept in circulation and hydrogen gas is harvested from the ends of the tubes. The hydrogen can be used on site, stored, or transported for use elsewhere
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