Four-stroke Engine Cycle Releases Hydrogen from Methane, Captures Carbon Dioxide

By adding a catalyst, a hydrogen separating membrane and carbon dioxide sorbent to the century-old four-stroke engine cycle, scientists have illustrated a laboratory – scale hydrogen reforming system that releases the green fuel at relatively low temperature in a procedure that can be scaled up or down to meet particular needs.

The procedure could offer hydrogen at the point of use of residential fuel cells or neighbourhood power plants, power production and electricity in natural-gas powered automobiles, fuelling of municipal buses or other hydrogen-based automobiles, and supplementing intermittent renewable energy sources like photovoltaics.

Known as the Co2/H2 Active Membrane Piston reactor, the device functions at temperatures much lower than traditional steam reforming procedures, consumes substantially less water and could also function on other fuels like methanol or bio-derived feedstock. It also captures and concentrates carbon dioxide emissions, a by-product that now lacks a secondary use, though that could alter in the future.

Unlike traditional engines that run at thousands of revolutions per minute, the reactor operates at just a few cycles per minute or more slowly, relying on the reactor scale and need rate of hydrogen production, and hence, there are no spark plugs as there is no fuel combusted.

Four-stroke engine cycle

“We already have a nationwide natural gas distribution infrastructure, so it is much better to release hydrogen at the point of use rather than trying to distribute it,” says Andrei Fedrorov, a Georgia Institute of Technology lecturer who has been working on CHAMP since 2008. “Our technology could release this fuel of choice wherever natural gas is available that could resolve on of the major limitations with the hydrogen economy.”

Federov’s lab first carried out the thermodynamic estimations suggesting that the four-stroke procedures could be modified to release hydrogen in relatively small amounts where it would be employed. The aim of the study were to prepare a modular reforming process that could operate at between 400 and 500 degree Celsius, use just two molecules of water for every molecule to methane to produce four hydrogen molecules, be able to scale down to meet particular requirements, and capture the leading carbon dioxide for potential utilization of sequestration.

“We intend to completely rethink how we crafted reactor systems,” says Fedorov. “To gain the sort of efficacy we needed, we realize we would require to dynamically altering the volume of the reactor vessel. We looked at the current mechanical systems that could do this.”

“We took the traditional chemical processing plant and prepared an analog using the magnificent machinery of the internal combustion engine,” says Fedorov. “The reactor is modular and scalable, so you could have one module or a hundred of modules depending on how much hydrogen you required. The procedures for reforming fuel, purifying hydrogen and capturing dioxide emission are all linked into one compact system.”