Avjet Biotech principal scientist discusses Red Wolf technology
North Carolina-based Avjet Biotech Inc., a developer of distributed refining systems and parent company of Red Wolf Refining, has released an overview of its biorefining process. The company’s patented RWR System uses a thermal catalytic process to refine triglycerides into biobased aviation fuels.
“The Red Wolf process produces true drop-in fuels from renewable resources,” said ABI CEO Donald Evans. “The capability of this refining system to create aviation biofuel from native feedstocks will help us support the U.S. military in its effort to reduce dependence on foreign oil.”
According to William Roberts, ABI principal scientist and a professor at North Carolina State University, the objective of the RWR process is to produce fungible drop-in replacement transportation fuels from a wide variety of renewable oils, including those sourced from oilseed crops, animal fats or algae. “The first step in the process is we take these fats, oils and lipids, and we mix them with hot water and hydrolyze them,” Roberts said. “This takes the fatty acids and breaks them off the glycerin backbone.” A thermocatalytic process then deoxygenates the fatty acids. “We drive the two oxygens off as carbon dioxide and we saturate any unsaturated bonds within the fatty acid,” he added.
The result is a straight chain, saturated hydrocarbon, Roberts said, which is an ideal molecule to reform into transportation fuels. According to Roberts, the next step in the process is to change the structure of the molecule to either increase the flash point or suppress the freeze point. Some cracking is also done, he said, which means some of the longer molecule chains are broken into shorter chains. “We’ve demonstrated the ability to take a number of different feedstocks and produce a number of different molecule blends to meet the fuel specifications that we’re aiming for,” Roberts continued.
Glycerin is one of the “waste” or coproducts that results from the technology, Roberts said. “This glycerin is a C3 oxygenated molecule that has some value.” The glycerin that comes out of the hydrolysis reactors is mixed with water. Roberts said the water can be recovered and reused, while the glycerin can be sold as a coproduct or burned to provide heat and power. “One of the advantages of the system that we use is to cleave the fatty acid off the glycerin, we use hot water rather than a catalyst,” Roberts added. While glycerin that comes out of a typical biodiesel process contains catalyst salts that have to be removed before the product is sold or burned, Roberts said that that issue is negated in the RWR process because hot water rather than a catalyst is used.
According to him, competing processes are generally based on a technology that uses additional hydrogen to drive off oxygen from the triglyceride feedstocks. “It saturates the bond between the fatty acid and the glycerin backbone and takes the glycerin and makes it into propane, and then you can saturate the bonds,” he said. One of the primary drawbacks of this hydrogen-adding process is that hydrogen consumption is large. “To make the process cost-competitive you really need to have it co-located with a refinery where you have access to lots of hydrogen and the ability to use lots of smaller fragments, because you have a hard time in that process controlling what the fatty acids eventually break into,” Roberts said.
The RWR process has been specifically designed to be cost-competitive at smaller, distributed scales. In fact, ABI is targeting 10 MMgy as the average size for plants employing the RWR process because these kinds of smaller plants are better equipped to operate on locally produced feedstocks, whether they are oilseeds or animal fats.