The demand for “green” methanol as a low-carbon fuel is rising, making it a valuable commodity, as well as a promising avenue for waste-carbon utilization, especially since it can be readily produced from “stranded” carbon sources, such as flare gas. At its landfill-gas processing plant in Houston, Montauk Renewables, Inc. (Pittsburgh, Pa.; www.montaukrenewables.com) is planning a pilot plant to deploy a novel technology developed by Emvolon (Woburn, Mass.; www.emvolon.com) to produce carbon-negative methanol from the site’s flare gas.
Emvolon’s process is very efficient and cost-effective at converting methane-containing streams, because its key technology utilizes a modified internal combustion engine (ICE) rather than a chemical reactor, resulting in a modular and scalable design.
“We operate the system to be very fuel-rich, and we’ve gone beyond anything that people have done in the literature. It is very difficult to ignite a mixture without any sort of external assistance once you have a very lean or rich mixture. It takes a lot of special controls to do this,” explains Emmanuel Kasseris, CEO of Emvolon.
The ICE has been specially tuned to handle this extremely fuel-rich environment to optimize it for the partial oxidation of a methane-containing stream into hydrogen and CO (syngas) instead of CO2 and water. “We make very high hydrogen concentrations in our syngas, so we also make power that can be used to run some of the utilities,” comments Kasseris. The syngas is then compressed and converted to liquid methanol using a conventional catalytic process. The pilot plant at Montauk Renewables is designed to produce over 15,000 gal/yr of green methanol, with plans to eventually expand to 2,400,000 gal/yr on that site.
“For the next generation of the technology, we have actually used the modified ICE as a compressor, reactor and expander to replace more expensive process equipment. We have gotten very high conversions, on par with the best reactors in the world using this engine technology,” adds Kasseris.
Within Emvolon’s modified catalytic diesel engine — based on a typical truck engine — the cylinders can be retrofitted with a custom catalyst-containing piston (photo). To further develop the process, Emvolon has partnerships underway with Waukesha and Clariant AG related to engine design and catalysis, respectively. ■