One major overarching goal in the United States is to have another source of energy the country does not need to import and could lead to lower carbon monoxide emissions than conventional fossil fuels.
That is where researchers at Sandia National Laboratories come in as they will use their expertise in protein expression, enzyme engineering and high-throughput assays as part of a multi-project, $34 million effort by the Advanced Research Projects Agency-Energy (ARPA-E) aimed at developing advanced biocatalyst technologies that can convert natural gas to liquid fuel for transportation.
ARPA-E calls its program Reducing Emissions using Methanotrophic Organisms for Transportation Energy (REMOTE) and it involves 15 different projects. Sandia is a part of a two-year award led by MOgene Green Chemicals, a wholly owned subsidiary of St. Louis-based MOgene, LC, and will work toward sunlight-assisted conversion of methane to butanol.
Methanotrophs are microbes that can metabolize methane. Sandia’s Blake Simmons, manager of the labs’ biofuels and biomaterial science and technology group, calls this microbe 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 a fuel in an internal combustion engine and, along with ethanol, is one of the best biofuel options for transportation energy.
“The need for hydrocarbons that are nonpetroleum in origin is still growing, including applications such as aviation and diesel engines,” Simmons said. “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 requires a special modification to effectively see use as a liquid fuel in vehicles, much like biomass needs conversion before it can be a drop-in fuel, he said.
“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,” said Simmons. Natural gas extracted from the ground is not renewable, but it is playing an increasingly important role for the Department of Energy and the nation’s energy supply.
Simmons said MOgene brings a great deal of organism expertise to the table, while Sandia offers enzyme engineering and other capabilities.
Using organisms to convert natural gas into liquid transportation fuels isn’t a new objective for the research community, Simmons said. “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,” he said. ARPA-E’s projects 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,” Simmons said. “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, Simmons thinks Sandia is up to the task based on the labs’ work with membrane proteins and various tools developed over the years.
“People have been trying to express this class of enzymes for a couple of decades, so this definitely won’t be a slam dunk,” Simmons said. “It’s been a confounding scientific challenge for the research community, and this is a notoriously difficult class of proteins. But we have the collective experience and capabilities at Sandia to figure it out.”