Scientists flip energy equation with solar leaf that converts CO2 into fuel

Researchers at the University of Illinois at Chicago say the fuel from carbon dioxide can remove the greenhouse gas from the atmosphere, and provides a sustainable type of fuel that is as cheap as a gallon of gas. 

Courtesy of University of Illinois at Chicago
At a lab at the University of Illinois, simulated sunlight powers a solar cell that converts atmospheric carbon dioxide directly into syngas.

It’s often smarter to borrow from nature than reinvent the wheel.

That was the approach of researchers at the University of Illinois at Chicago (UIC) to remove carbon dioxide (CO2 ) from the atmosphere, and convert it into an efficient, inexpensive fuel.

The result: an artificial leaf that turns CO2  into fuel, "at a cost comparable to a gallon of gasoline" could render fossil fuel obsolete, according to the researchers.

The “leaf” is one of a growing number of inventions that mimic photosynthesis to remove excess carbon from the atmosphere, and convert it into new, sustainable forms of energy to power our world.

“The new solar cell is not photovoltaic — it’s photosynthetic,” said Amin Salehi-Khojin, an assistant professor of mechanical and industrial engineering at UIC and the study’s lead author, in a statement. “Instead of producing energy in an unsustainable one-way route from fossil fuels to greenhouse gas, we can now reverse the process and recycle atmospheric carbon into fuel using sunlight.”

The solar cells Dr. Salehi-Khojin and his team built function like a plant’s leaves. Except instead of converting carbon dioxide into sugar, the artificial leaf converts the gaseous compound into synthesis gas — a mixture of hydrogen and carbon monoxide. Synthesis gas, or syngas, could be burned for fuel, or converted into diesel or other hydrocarbon fuels.

The concept of reduction reaction — converting CO2  into a burnable form of carbon — isn’t new. But scientists previously relied on silver and other expensive precious metals to break gas into storable energy. UIC researchers took a different approach. They relied on a nano-structured compound, a transition metal dichalcogenide (TMCD), to break down carbon dioxide. They paired a kind of TMCD — a nanoflake tungsten — with an ionic liquid inside a two-compartment, three-electrode electrochemical cell.

When light strikes the "leaf," hydrogen and carbon monoxide bubble from the cathode, while free oxygen and hydrogen ions are released from the anode.  

Leafs could be spread throughout a solar farm, or used in smaller applications, the researchers said.

The invention isn’t the only one of late to use the concept of photosynthesis to create a new form of energy. The researchers note the process they employed has been used to create other forms of hydrogen energy. Researchers at Harvard University have even created hydrogen through synthetic photosynthesis in a process they say is 10 times more efficient than in nature, as The Christian Science Monitor’s Jason Thomson reported in June.

That process relies on bacteria. The system is confined to a jar with just two electrodes, Ralstonia eutropha bacteria, and water. When an electric current passes through the electrodes, it breaks the water molecules down, releasing hydrogen gas.

“You can use hydrogen as a source of energy, [and] burn it,” co-author Pamela Silver of Harvard University told the Monitor. “Instead, we decided to take advantage of bacteria that take in hydrogen and carbon dioxide and use them to grow.”

As they grow, explains Dr. Silver, these organisms produce certain compounds. The bacteria can be genetically engineered to make useful things like alcohol and plastic precursors.

While the artificial leaf UIC researchers invented is just artificial, not bionic, it’s applicability isn’t confined to this world. They note it can even be used if water is found on Mars. Mars’s atmosphere is mostly CO2 , after all.

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.