Edan Prabhu took part in the Global Energy Show in Calgary, June 13-15, 2023, presenting the Oxiperator for oxidizing weak methane without a catalyst. The following abstract provides an overview of what he shared with the energy industry:
Mitigating Weak Methane: Oxidizing without a Catalyst
Objective: A New Solution for Weak Methane Oxidation
In oil, gas and coal operations, weak methane emissions (below 2% volumetric concentration or 20,000 ppmv) have historically been vented or evaded capture. Newly proposed Canadian methane regulations and the Global Methane Pledge will challenge existing methane mitigation tools, especially for weak methane. At least half of global methane emissions are “weak.”
Research on catalysts for oxidation of weak methane, such as methane slip from lean-burn engines, have been partially successful, but catalyst cost, poisoning and longevity are concerns. Regenerative Thermal Oxidizers are bulky, take a long time to heat up, and require flow reversals every few minutes. A new solution is needed.
Method: High Temperature Porous Heat Transfer
A novel high-temp, all-metal, porous heat exchanger has achieved oxidation of methane at concentrations as low as 0.6% by volume in air, by harnessing the energy inherent in methane itself. It shows promise to oxidize methane as low as 0.3%, even 0.2% (2,000 ppm). The exchanger has been tested at 25 cubic feet per minute (cfm) of air flow.
The porous heat exchanger can operate at pressures up to 10 or more atmospheres. Higher pressure may offer several advantages. Because gas density increases with pressure, the heat exchanger will be smaller. The higher pressure could be used to power a gas turbine, which in turn could drive a compressor that provides the pressure. With methane concentrations as low as 1.5%, the system will be able generate surplus power.
The porous heat exchanger can have several uses for methane. It could also be used to oxidize and remove VOCs from industrial waste gases.
Process: Develop and Demonstrate
Plans are underway to further develop the exchanger, test it to its pressure, temperature and methane oxidation limits, and to then demonstrate it for oxidizing methane slip from lean-burn gas engines. Exchangers with capacity for 1,000 cfm, 10,000 cfm and 40,000 cfm air flow are planned. Demonstration projects on lean burn engines and tank vapor emissions are planned for Alberta oil and gas production.
The porous heat exchangers will be manufactured using 3D printing, thus greatly reducing material use while also increasing heat transfer. Participants include Carnegie Mellon University for its metallurgy and high temperature 3D printing expertise, University of California Davis for its high-temperature high-pressure microchannel heat exchanger expertise, and Colorado State University for its lean burn gas engine expertise, the American Bureau of Shipping concerned with lean-burn engine methane slip on ships, and Kaiser Aluminum’s Imperial Machine and Tool, for its 3D printing capability.
The testing will be witnessed by independent experts and the test results reviewed by peer groups.
Edan Prabhu is the founder and CEO of Prabhu Energy Labs. A mechanical engineer and inventor, he has spent a lifetime on energy innovation. He has extensive experience with wind, solar, nuclear and fossil fuels, serving on the National Biomass Advisory Board after 20+ years at public utility Southern California Edison. Edan continues to champion sustainable energy, clean use of waste fuels and methane abatement. He was awarded 9 US patents on weak methane and other waste fuels.