Converting gaseous waste substrates to liquid fuels

As most people are aware, waste gases from human applications are making their way into the atmosphere leading to adverse climate changes; this has led to efforts across the globe to find ways to either capture and hold waste gases or use them in another productive way.

In this new effort, the research team looked to see if it might be possible to capture waste gases that are normally expelled from applications such as steel making facilities or coal fired power plants and convert them into a type of fuel that could be used by transport trucks as a replacement for diesel fuel.

To find out, the team came up with a two-stage process. The first stage involved building a bioreactor that converted a mixture of carbon dioxide, dihydrogen, or carbon monoxide gasses to acetic acid (the acid that makes vinegar taste sharp).

The bioreactor did its job using anaerobic acetogen Moorella thermoacetica. In the second stage, the acetic acid was fed as a substrate to a secondary bioreactor where it was converted into a lipid—the second bioreactor worked aerobically by making use of an engineered yeast, Yarrowia lipolytica.

The lipid produced, the team reports, was in the form of an oil that could be used as a replacement for diesel fuel in transport trucks—they also note that the process is relatively inexpensive.

The team at MIT has been working on the project for the past five years, which they have now patented and licensed to GTL Biofule Inc., a company that has been testing the process at a pilot plant in China since last fall. The project has been successful to the extent that a much larger plant has been planned with construction to start very soon.

The researchers are confident their process will scale well, and if they are right, they envision plants being built to capture and convert gases from a variety of applications, including farm waste and garbage dumps.