Sandia LabNews

Researchers converting natural gas to liquid transportation fuel


Sandia researcher Eizadora Yu prepares biomass harvested from liquid fungal cultures for nucleic acid analysis. The cultures come from the endophytic fungus Hypoxylon sp, which produces compounds potentially used for fuel. (Photo by Dino Vournas)

A multi-project, $34 million effort by the Advanced Research Projects Agency – Energy (ARPA-E) is aimed at developing advanced biocatalyst technologies that can convert natural gas to liquid fuel for transportation, and Sandia will use its expertise in protein expression, enzyme engineering, and high-throughput assays to help make it happen.

The ARPA-E program, known as REMOTE, or Reducing Emissions using Methanotrophic Organisms for Transportation Energy, involves 15 projects. Sandia is a part of a two-year, $1.5 million award led by MOgene Green Chemicals, a subsidiary of St. Louis-based MOgene, LC, and will work toward “sunlight-assisted conversion of methane to butanol.”

The broad goal is to have another source of energy in the US that doesn’t have to be imported and could lead to lower CO emissions than conventional fossil fuels.

Methanotrophs are microbes that can metabolize methane. Blake Simmons (8630) calls them the “poster child” of organisms capable of metabolizing and converting methane. The goal of the project is to engineer pathways from these organisms into another microbial host that can generate butanol. Butanol can be used as a fuel in an internal combustion engine and has, along with ethanol, long been considered one of the best biofuel options for transportation energy.

“The need for hydrocarbons that are non-petroleum in origin is still growing, including for applications such as aviation and diesel engines,” says Blake. “But in its natural state, you’re not going to readily burn natural gas in those types of engines, and the same goes for some combustion engines.” Natural gas, he says, requires a special modification to be used effectively as a liquid fuel in vehicles, much like biomass needs to be converted before it can be used as a drop-in fuel.

“With biomass, we are essentially taking something that exists in nature and converting it into a low-cost, low-carbon, domestically sourced fuel. With this project, we’re using natural gas as the input rather than biomass,” Blake says. Natural gas extracted from the ground is not renewable, he points out, but is playing an increasingly important role for DOE and the nation’s energy supply.

Blake says MOgene brings a great deal of organism expertise to the table, while Sandia offers enzyme engineering and other capabilities.

Improving on what nature has given us

Using organisms to convert natural gas into liquid transportation fuels isn’t a new objective for the research community, Blake says. “There have been plenty of investigations into this in the past, since there are plenty of organisms in nature that thrive and survive and multiply off of natural gas metabolism. The problem, though, is that they exist in unique, tailored environments and are typically very slow at what they do.” ARPA-E’s projects, he says, are hoping to improve upon “what nature has given us” and develop new, more efficient pathways to speed up the process and convert gaseous feedstocks at a pace and scale that is commercially viable. Currently, there are no proven biological methods for converting gaseous inputs such as natural gas into butanol.

“What we and others are doing is looking at the core metabolism of these microbes,” Blake says. “Then, we can either engineer it to make it faster in native organisms, or we can take the metabolism out of those organisms and put it in something more industrially relevant.”

Though the research community has wrestled with this problem before without much success, Blake thinks Sandia might be up to the task.

“Time and time again, through various LDRDs [Laboratory Directed Research and Development projects] and our work at the Joint BioEnergy Institute [JBEI], Sandia has proven its ability to express proteins that are difficult to express,” Blake says. The lab also possesses engineering and modeling tools as well as the ability to build high-throughput custom enzyme assays, significant proficiencies that can lead to better performance in enzymes. Few research organizations, says Blake, offer that package of technical capabilities to tackle a problem like this one.

Blake acknowledges that meeting the objectives will not be a simple or trivial endeavor. “People have been trying to express this class of enzymes for a couple of decades,” he says. “So this definitely won’t be a slam dunk.”

But based on Sandia’s work with membrane proteins and various tools developed over the years, he thinks the lab is up to the test. “It’s been a confounding scientific challenge for the research community, and this is a notoriously difficult class of proteins,” he admits. “But I think we have the collective experience and capabilities at Sandia to figure it out.”