Scientists at the Department of Energy's Pacific Northwest National Laboratory (PNNL) developed a system to convert methane into a deep green, energy-rich, gelatin-like substance that can be used as the basis for biofuels and other bioproducts, specialty chemicals and even animal feed.
Manure from dairy cows, cattle and other livestock that provide us food often breaks down into methane. Drilling processes used to obtain the oil and natural gas we use to drive cars and trucks or heat our homes often vent or burn off excess methane to the atmosphere.
PNNL scientists aimed to solve this problem by getting two different micro-organisms to live together in harmony. One is a methane-loving methanotroph, which is found underground near places where natural methane production typically occurs. The other is a photosynthetic cyanobacterium that resembles algae, which uses light along with carbon dioxide to produce oxygen.
These two micro-organisms co-exist in a bioreactor at PNNL. Here, methane gas from a Washington dairy farm and Colorado oil fields was fed to the microbes. One bacterium, Methylomicrobium alcaliphilum 20Z, ate the methane and produced carbon dioxide and energy-rich biomass made up largely of a form of carbon that can be used to produce energy. The other micro-organism, Synechococcus species 7002, uses light to produce the steady stream of oxygen its counterpart needs to carry out the methane-consuming reaction.
Each one accomplishes a significant duty while supplying the other with a substance it needs to survive. According to PNNL, the micro-organisms are engaging in a "productive metabolic coupling."
The PNNL process produces a cleaner biogas, either liquid or solid, with either the flick of a switch or exposure to sunlight. When there's methane to convert, the cyanobacteria absorb light and use carbon dioxide as fuel to produce oxygen. When there is not much methane, researchers dim the lights to reduce the oxygen, which slows the action of the methanotrophs.