Unique photo-catalyst material turns CO2 emissions into renewable hydrocarbon fuels

March 3, 2017 by Robert (Chris) Scoggins, Texas A&M University
Unique photo-catalyst material turns CO2 emissions into renewable hydrocarbon fuels

Researchers with the Department of Mechanical Engineering at Texas A&M University are making the best use of our energy waste—turning one of our most potent pollutants and greenhouse gasses, carbon dioxide (CO2), into hydrocarbon fuels that can help the environment and solve growing energy needs.

"We're essentially trying to convert CO2and water, with the use of the sun, into in a process called artificial photosynthesis," said Dr. Ying Li, associate professor of and principal investigator. "In this process, the photo-catalyst material has some unique properties and acts as a semiconductor, absorbing the sunlight which excites the electrons in the semiconductor and gives them the electric potential to reduce water and CO2 into carbon monoxide and hydrogen, which together can be converted to liquid ."

The first step of the process involves capturing CO2from emissions sources such as power plants that contribute to one-third of the global carbon emissions. As of yet, there is no technology capable of capturing the CO2, andat the same time re-converting it back into a source that isn't expensive. The material, which is a hybrid of titanium oxide and magnesium oxide, uses the to absorb the CO2 and the titanium oxide to act as the photo-catalyst, generating electrons through sunlight that interact with the absorbed CO2 and water to generate the fuel.

The project is still in the fundamental research stage. One of the challenges with this technology is that the current of converting CO2and water into renewable solar fuels remains low, less than a few percent. According to Li, the conversion process also takes considerable time and the material can only absorb a fraction of the emitted sunlight. For Li and his team, solving these issues revolves around engineering more efficient materials with nano-scale structures and advancing the reactor design so that the materials placed within the reactor can absorb sunlight in the most efficient manner.

"There are also other considerations," said doctoral student Huilei Zhao, a student contributing to the ongoing research in Li's research group. "Concentrated sunlight exposure can lead to a higher conversion efficiency and we've found that if we operate at a higher temperature with this reaction, the conversion efficiency can be dramatically increased."

The project is a part of a five-year research grant and CAREER Award for Li from the National Science Foundation, and is currently in its third year. By the end of the project, Li hopes to have developed a higher level of conversion efficiency and determine if the process can be commercially viable.

"There are two different ways to quantify the efficiency," said Li. "What is the fraction of the solar energy we are storing into fuels, or what is the fraction of CO2 being converted to fuels? In either case, we need to achieve a near 10-percent efficiency to make the process economically competitive."

Li explains that the commercial viability of this material is crucial, and while such as oil and natural gas remain cheap, low conversion rates do not serve to make the material attractive in meeting national energy needs. He says, however, that too many people are thinking in the short term.

"We may think in the current stage that this technology is not competitive with fossil fuels," Li said. "But, if we think in the long run, our fossil fuels can only support our energy needs for maybe a couple hundred years if we use them at the current rate. What will happen after that? We will still need these liquid hydrocarbon fuels to power our machines, vehicles and airplanes. Electricity made through renewable resources alone will not be enough because we cannot store and transport it effectively. Therefore, we believe this new technology of producing renewable hydrocarbon fuels is important in dealing with both global climate issues and our need for sustainable energy."

Explore further: Researchers discover a cell in spinach that uses sunlight to produce electricity and hydrogen

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1 / 5 (1) Mar 03, 2017
Huh? They're talking about capturing CO2 from power plant "flue" gases. So we burn fossil fuels, capture the CO2 and we're now green. When we burn the captured gases, convert to fuel we've simply re-constituted the oil effluent to be reburned later on. That's NOT green. That's simply delayed, not avoided pollution. Then they state "after the oil is all burned" what will we do? Well this process appears to require flue gases to work so it's over when the oil burning is over. Duh? Lastly, this process would be "the best" if it grabbed free CO2 from the air now, not flue gases. That way it's removing oil based CO2 as well as natural CO2 so when the oil is gone it doesn't matter, we have the atmospheric CO2 to use. If this was developed to be very efficient we could and should stop oil burning all together as soon as we can. The possibility is there with this process.
not rated yet Mar 05, 2017
That's NOT green.

Consider that the powerplant may be running on the same synthetic fuel you just created.

It's simply more efficient to capture the CO2 at the point of origin rather than filter it from the air.

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