Four Stroke Engine Cycle Produces Hydrogen From Methane, Captures Carbon Dioxide

Four Stroke Engine Cycle Produces Hydrogen From Methane, Captures Carbon Dioxide
Georgia Tech professor Andrei Fedorov (left) and an undergraduate research assistant Yuzhe Peng are shown with the laboratory-scale hydrogen reforming system that produces the green fuel at relatively low temperature in a process that can be scaled up or down to meet specific needs. Credit: Candler Hobbs, Georgia Tech

In an internal combustion- four stroke engine (ICE), the ignition and combustion of the fuel occur within the engine itself. The basic process of the engine is releasing energy from fuel and air and then convert the energy into work through combustion. But the engine will not an internal combustion- four stroke engine anymore when it being transformed into a modular reforming reactor. It will not an IC engine when it could create hydrogen to charge cells wherever there’s a natural gas supply available.

Scientists did the same and figure out a laboratory-scale hydrogen reforming system. This new system produces the green fuel at a relatively low-temperature process that can meet specific needs. Scientists just added a catalyst, a hydrogen separating membrane and carbon dioxide sorbent to the century-old four stroke engine cycle to build this hydrogen reforming system.

The system is known as the CO2/H2 Active Membrane Piston (CHAMP) reactor. It needs temperature much lower than conventional steam reforming processes and few amount of water to operate. In addition, it captures carbon dioxide emissions. It could also work on other fuels. For example, methanol or bio-derived feedstock.

A professor from the Georgia Institute of Technology said, “We already have a nationwide natural gas distribution infrastructure. It’s much better to produce hydrogen at the point of use rather than trying to distribute it. Our technology could produce this fuel of choice wherever natural gas is available, which could resolve one of the major challenges with the hydrogen economy.

Conventional IC engines operate at 1000 revolutions per minute. But this new reactor operates at only a few cycles per minute or more slowly, It all relies on the reactor scale and appropriate rate of hydrogen production. And the most important it does not have spark plugs because there’s no fuel combusted.

The key to the reaction process of this reactor is the variable volume provided by a piston rising and falling in a cylinder. As with a conventional engine, a valve controls the flow of gasses into and out of the reactor as the piston moves up and down. The four stroke engine system works like this:

  • Natural gas (methane) and steam are drawn into the reaction cylinder through a valve as the piston inside is lowered. The valve closes once the piston reaches the bottom of the cylinder.
  • The piston rises into the cylinder, compress the steam and methane as the reactor getting heat. Once it reaches approximately 400 degrees Celsius, catalytic reactions take place inside the reactor, forming hydrogen and carbon dioxide. The hydrogen exits through a selective membrane, and the pressurized carbon dioxide is adsorbed by the sorbent material, which is mixed with the catalyst.
  • Once the hydrogen has exited the reactor and carbon dioxide is tied up in the sorbent, the piston is lowered, reducing the volume (and pressure) in the cylinder. The carbon dioxide is released from the sorbent into the cylinder.
  • The piston is again moved up into the chamber and the valve opens, expelling the concentrated carbon dioxide and clearing the reactor for the start of a new cycle.

READ: New Technique of Deriving Hydrogen from Grass Using Just Sunlight and a Cheap Catalyst

Professor Fedorov said, “All of the pieces of the puzzle have come together. The challenges ahead are primarily economic in nature. Our next step would be to build a pilot-scale CHAMP reactor.

In today’s date, the hydrogen is created in hight temperature reforming process. The methane is then combined with steam at about 900 degrees Celsius. This process requires lots of water. At last, the outcoming low-density gas transported to where it will be used.

To produce hydrogen from for stroke engine, scientists primarily observed thermodynamic calculations. They just wanted to create a modular reforming process that could operate at between 400 and 500 degrees Celsius. Hence, the resulting process operates under the lower temperature and uses only 2 water molecules. It is able to scale down to meet the specific needs and capture the resulting carbon dioxide for potential utilization or sequestration.

In addition, the system is able to produce 100 kilograms hydrogen per day. The volume and piston speed in the CHAMP reactor can be adjusted to meet hydrogen demands while matching the requirements for the carbon dioxide sorbent regeneration and separation efficiency of the hydrogen membrane.

Fedorov said, “We wanted to completely rethink how we designed reactor systems. To gain the kind of efficiency we needed, we realized we’d need to dynamically change the volume of the reactor vessel. We looked at existing mechanical systems that could do this. Then we realized that this capability could be found in a system that completed more than a century of improvements: the internal combustion engine.”

The reactor is scalable and modular, so you could have one module or a hundred of modules depending on how much hydrogen you needed. The processes for reforming fuel, purifying hydrogen and capturing carbon dioxide emission are all combined into one compact system.