Researchers are working on multiple ways that microorganisms, specifically bacteria, can be used to create energy.Here are a few ways they are harnessing the billions of years of microbial evolution to make energy cleaner and more reliable.
A group at MIT is working to train microbes that usually make bioplastics to make a fuel called isobutanol, which can be directly substituted for or mixed with gasoline.
The team, whose research was recently published in the journal Applied Microbiology and Biotechnology, has programmed the microbes to make a fuel instead of their natural carbon compounds. When the bacteria, called Ralstonia eutropha, are put in a nutrient-poor environment, they start making carbon-based compounds that they can store and break down as an energy source later.
'What it does is take whatever carbon is available, and stores it in the form of a polymer, which is similar in its properties to a lot of petroleum-based plastics,' study researcher Christopher Brigham said in a statement from the university.
By tweaking the genes of the microbes, the team forced the microbes to make the fuel isobutanol instead of these polymers.
The team is currently working to get the bacteria to use carbon dioxide or other carbon-based waste products as their starting product, instead of the sugars they are currently using.
The system would also need to be scaled up to industrial levels before it is commercially viable.
A group at Stanford University is working on a microbe-based system to produce methane, which can be used the same way natural gas is used currently.
These microbes, called methanogens, are able to turn energy into methane. They think they could use a tank of methanogens to turn clean electricity from the wind or sun into methane, which could be used as a storage product or as a source of chemical compounds for industry.
'Most of today's methane is derived from natural gas, a fossil fuel,' study researcher Alfred Spormann, said in a statement from Stanford. 'And many important organic molecules used in industry are made from petroleum. Our microbial approach would eliminate the need for using these fossil resources.'
Methane can be used to fuel aeroplanes, ships and other vehicles.
Seaweed, at least in North America, is a relatively unexploited source of nutrition. It is high in sugars and lacks the tough proteins called lignins that make getting energy from other plant matter, like cornstalks, difficult, even for bacteria.
So, instead of making bioethanol from corn, some researchers think they could make it from other plants, like seaweed, without disrupting the food manufacturing chain.
That all sounds great, but there's one problem: the energy-containing compound in seaweed are in a form called alginate. Alginate is a gummy sugar substance that makes up the cell walls of the algae. But alginate is also strong: It stands up to most reactions that would disassemble most other sugars.
To beat alginate, a team of researchers led by Yasuo Yoshikuni, of Bio Architecture Lab in California, are using microbes they've isolated from the ocean to break down the gummy sugars and turn them into biofuels and other chemicals.
The only problem? Seaweed farms are pretty hard to sustain in large numbers, so it might be tough to expand from lab samples to industrial-scale production.
Humans get rid of their sewage and other waste using energy and tons of money every year. This makes researchers like Oriana Bretschger, of the J. Craig Venter Institute in San Diego, wonder if there's anything better we can be doing with it. Instead of using energy, could we be using it to create energy?
'It's a substantial energy resource that we just end up landfilling,' Bretschger told New Scientist. 'If we could recover the energy we could do waste water treatment for free.'
Bretschger's group announced in March that they had developed a 380-liter microbial fuel cell, which can break down organic waste to produce electricity. The microbes they use have been tinkered with to make them better at digesting organic waste, the kind found in sewage.
They hope with further improvement, they could harvest 30 to 40 per cent of the energy trapped in wastewater.
Another group, at a company called Terrabon, is also working to harness waste and turn it into energy using what they call the MixAlco system. The system converts low-cost, readily available biomass into valuable chemicals that can be processed into renewable gasoline fuels, their website says.
By using a proprietary combination of naturally occurring microbes from natural habitats -- like the fermenting vat stomachs of cattle, the guts of termites, and methane-producing swamps -- they say they can digest all different kinds of waste.
They claim their reactors can make energy from not just wastewater, but also from things like forest product residues such as wood chips, wood molasses and other wood waste, and non-edible energy crops.
Their website claims their first bio-refinery will be fully operational in 2013.
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