Solar Energy, Technology Key to Patented “Green” Methane Breakthrough
Researchers from the University of Michigan and McGill University have developed a way to harvest solar energy and convert it into a carbon-neutral “green” methane that is capable of replacing natural gas. “Green” methane can be used as a form of synthetic gas because 90% of natural gas is comprised of methane.
“This is needed now because there is a desire to reduce and recycle CO2 and to move to a carbon-neutral economy,” said Zetian Mi, professor of electrical engineering and computer science at the University of Michigan, who together with Jun Song, professor of materials engineering at McGill University, led the research.
The process for making “green” methane takes a page from nature’s playbook; it uses solar cell wafers to increase the efficiency of its artificial photosynthesis process. Because solar cell efficiency is 20% or higher, Mi and his team of researchers decided to use silicon (Si) solar cells to amp up the artificial photosynthesis process to make it more efficient.
Essentially, the process creates a way to recycle stored CO2 or CO2 from smokestacks and convert it into a synthetic fuel that heavy industrial companies – like oil and gas, petrochemical, mining, and other companies – can use for their operations. Technologies that capture atmospheric CO2 and the infrastructure for transporting and distributing methane already exist.
“The current approach to reducing CO2 emission often relies on transporting CO2 through pipelines and storage underground. We envision that large emitters of CO2 in the future can put that into a solar farm and generate [a clean burning] fuel,” Mi said.
To develop the “green” methane process, the team of researchers needed to break apart water molecules, figure out a way to bend a CO2 bond so that it can be used to form a new chemical and design a catalyst that could attach the hydrogen to carbon effectively.
Ultimately, the team designed a catalyst device – made from a solar cell wafer covered with nanowires that are dotted with copper and iron nanoparticles – that can break down and reconnect carbon and hydrogen. The device inputs include sunlight and a thin film of water. In the future, such a device can also be designed to use electricity as an energy source when the sun isn’t shining.
“It’s a technology with a lot of promise. There is no roadblock in terms of its scalability because this device is made of GaN [Gallium Nitride] and Si, the two most-produced semiconductors, and earth-abundant catalysts,” Mi said, noting that the patented technology can be commercially available within the next five to ten years. The University of Michigan holds the patents for this artificial photosynthesis device.
Mi’s team has been working on artificial photosynthesis technology for 10 years. More recently, his team started collaborating with Song’s team at McGill University and with researchers at McMaster University on this project.
Emissions Reduction Alberta, the Engineering Council of Canada, and the University of Michigan College of Engineering’s Blue Sky Program funded their research.
by Editor