Bioconversion Process Can Bring Life to Natural Gas Market

Methanotroph image courtesy of Intrexon.

Industry leaders have partnered to determine the commercial scalability of a biological process that can convert natural gas into isobutanol. Natural gas is currently experiencing a surplus within the chemical and energy industry. Isobutanol, however, has the potential to become a valuable liquid fuel. Using this biological process to convert natural gas into isobutanol might therefore have significant economic results.

Isobutanol has a lot of potential to replace gasoline as a liquid fuel. First, the fuel is cleaner burning due to its oxygen to carbon ratio. As a result, it burns with less carbon monoxide and without nitrogen oxides (NO_x) or sulfur dioxide. Isobutanol also has a higher energy density than ethanol, so blending gasoline with isobutanol instead of ethanol will have a benefit to customers at the pump.

Natural gas, however, is currently experiencing a large surplus in industry. As a result, it is often flared at the wellhead rather than shipped to market. This is done to limit harmful emissions. For example, a lack of pipeline forces about one third of all natural gas produced by the Bakken oil field to be flared at the wellhead.

Intrexon Energy Partners (IEP) and Dominion Energy plan to use a bioengineered methanotroph bacteria to convert this surplus methane into isobutanol and farnesene (α: 3,7,11-trimethyl-1,3,6,10-dodecatetraene) under aerobic conditions and standard temperature and pressure (STP).

"We are excited to partner with IEP and help realize the promise of their [gas to liquid] platform to harness a plentiful feedstock in natural gas for the bio-production of isobutanol. Dominion is committed to being a good environmental steward while providing reliable, affordable energy services for our customers," said Diane Leopold, president of Dominion Energy.

Methanotroph metabolic process. Image courtesy of Intrexon.

The metabolic process of the bacteria will first convert the methane into methanol and then into pyruvate (the conjugate base of 2-oxopropanoic acid) before producing the isobutanol product. IEP reports that this process uses methane as the sole carbon substrate under STP. Therefore, this could help to reduce the cost of thermochemical conversion methods and the use of expensive plant-based feeds that compete with food crops.

IEP also reports that the metabolic process has a theoretical yield twice as large as conventional commercial yeast products. They therefore predict that the process will be profitable within the first year of production for small-scale plants.

From the first looks of it, the biggest effort of the process might be the separation of the isobutanol product from the feed, by-products, organic matter and other contents needed to keep the microbes alive.

Do you see isobutanol as a future liquid fuel replacement in the automotive industry? Is this the process to finally utilize all the wasted energy potential by flaring natural gas? Comment below.