A fossil fuel technology that doesn't pollute

A fossil fuel technology that doesn't pollute
L.S. Fan, Distinguished University Professor in Chemical and Biomolecular Engineering at The Ohio State University, holds samples of materials developed in his laboratory that enable clean energy technologies. Credit: Jo McCulty, The Ohio State University.

Engineers at The Ohio State University are developing technologies that have the potential to economically convert fossil fuels and biomass into useful products including electricity without emitting carbon dioxide to the atmosphere.

In the first of two papers published in the journal Energy & Environmental Science, the engineers report that they've devised a process that transforms shale gas into products such as methanol and gasoline—all while consuming carbon dioxide. This process can also be applied to coal and biomass to produce useful products.

Under certain conditions, the consumes all the carbon dioxide it produces plus additional carbon dioxide from an outside source.

In the second paper, they report that they've found a way to greatly extend the lifetime of the particles that enable the chemical reaction to transform coal or other fuels to electricity and useful products over a length of time that is useful for commercial operation.

Finally, the same team has discovered and patented a way with the potential to lower the capital costs in producing a fuel gas called synthesis gas, or "syngas," by about 50 percent over the traditional technology.

The technology, known as chemical looping, uses metal oxide particles in high-pressure reactors to "burn" and biomass without the presence of oxygen in the air. The metal oxide provides the oxygen for the reaction.

Chemical looping is capable of acting as a stopgap technology that can provide clean electricity until renewable energies such as solar and wind become both widely available and affordable, the engineers said.

"Renewables are the future," said Liang-Shih Fan, Distinguished University Professor in Chemical and Biomolecular Engineering, who leads the effort. "We need a bridge that allows us to create clean energy until we get there—something affordable we can use for the next 30 years or more, while wind and solar power become the prevailing technologies."

Five years ago, Fan and his research team demonstrated a technology called coal-direct chemical looping (CDCL) combustion, in which they were able to release energy from coal while capturing more than 99 percent of the resulting carbon dioxide, preventing its emission to the environment. The key advance of CDCL came in the form of iron oxide particles which supply the oxygen for chemical combustion in a moving bed reactor. After combustion, the particles take back the oxygen from air, and the cycle begins again.

The challenge then, as now, was how to keep the particles from wearing out, said Andrew Tong, research assistant professor of chemical and at Ohio State.

While five years ago the particles for CDCL lasted through 100 cycles for more than eight days of continuous operation, the engineers have since developed a new formulation that lasts for more than 3,000 cycles, or more than eight months of continuous use in laboratory tests. A similar formulation has also been tested at sub-pilot and pilot plants.

"The particle itself is a vessel, and it's carrying the oxygen back and forth in this process, and it eventually falls apart. Like a truck transporting goods on a highway, eventually it's going to undergo some wear and tear. And we're saying we devised a particle that can make the trip 3,000 times in the lab and still maintain its integrity," Tong said.

This is the longest lifetime ever reported for the oxygen carrier, he added. The next step is to test the carrier in an integrated coal-fired chemical looping process.

Another advancement involves the engineers' development of chemical looping for production of syngas, which in turn provides the building blocks for a host of other useful products including ammonia, plastics or even carbon fibers.

This is where the technology really gets interesting: It provides a potential industrial use for carbon dioxide as a raw material for producing useful, everyday products.

Today, when carbon dioxide is scrubbed from power plant exhaust, it is intended to be buried to keep it from entering the atmosphere as a greenhouse gas. In this new scenario, some of the scrubbed carbon dioxide wouldn't need to be buried; it could be converted into useful products.

Taken together, Fan said, these advancements bring Ohio State's chemical looping technology many steps closer to commercialization.

He calls the most recent advances "significant and exciting," and they've been a long time coming. True innovations in science are uncommon, and when they do happen, they're not sudden. They're usually the result of decades of concerted effort—or, in Fan's case, the result of 40 years of research at Ohio State. Throughout some of that time, his work has been supported by the U.S. Department of Energy and the Ohio Development Services Agency.

"This is my life's work," Fan said.

His co-authors on the first paper include postdoctoral researcher Mandar Kathe; undergraduate researchers Abbey Empfield, Peter Sandvik, Charles Fryer, and Elena Blair; and doctoral student Yitao Zhang. Co-authors on the second paper include doctoral student Cheng Chung, postdoctoral researcher Lang Qin, and master's student Vedant Shah. Collaborators on the pressure adjustment assembly work include Tong, Kathe and senior research associate Dawei Wang.

The university would like to partner with industry to further develop the technology.

The Linde Group, a provider of hydrogen and synthesis gas supply and plants, has already begun collaborating with the team. Andreas Rupieper, the head of Linde Group R&D at Technology & Innovation said that the ability to capture in hydrogen production plants and use it downstream to make products at a competitive cost "could bridge the transition towards a decarbonized hydrogen production future." He added that "Linde considers Ohio State's chemical looping platform technology for to be a potential alternative technology for its new-built plants".

The Babcock & Wilcox Company (B&W), which produces clean energy technologies for power markets, has been collaborating with Ohio State for the past 10 years on the development of the CDCL technology - an advanced oxy-combustion technology for electricity production from coal with nearly zero carbon emissions. David Kraft, Technical Fellow at B&W, stated "The CDCL process is the most advanced and cost-effective approach to carbon capture we have reviewed to date and are committed to supporting its commercial viability through large-scale pilot plant design and feasibility studies. With the continued success of collaborative development program with Ohio State, B&W believes CDCL has potential to transform the power and petrochemical industries."

Explore further

A milestone for new carbon-dioxide capture/clean coal technology

More information: Mandar Kathe et al. Utilization of CO2 as a partial substitute for methane feedstock in chemical looping methane–steam redox processes for syngas production, Energy & Environmental Science (2017). DOI: 10.1039/C6EE03701A

Cheng Chung et al. Chemically and physically robust, commercially-viable iron-based composite oxygen carriers sustainable over 3000 redox cycles at high temperatures for chemical looping applications, Energy & Environmental Science (2017). DOI: 10.1039/C7EE02657A

Journal information: Energy & Environmental Science

Citation: A fossil fuel technology that doesn't pollute (2018, January 2) retrieved 19 October 2019 from https://techxplore.com/news/2018-01-fossil-fuel-technology-doesnt-pollute.html
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Jan 02, 2018
This seems a bit msileading. From the linked abstract I just get that they increase syngas purity and instead of emitting CO2 they are emitting CO (which is not as much a greehouse gas but pretty toxic in its own right)

The way the above article is worded it sounds like they magically make less carbon while pulling carbon out of the ground. But reality doesn't work like that (not even magic works like that)

Jan 02, 2018
It still looks like reverse alchemy to me, converting gold into lead. Now if they were converting solar energy into useful fuels and utilizing waste CO2 in the process thereby creating an energy storage medium I would say bravo.

Other than that all they are creating is a black hole which consumes grant money.

Jan 02, 2018
"instead of emitting CO2 they are emitting CO (which is not as much a greehouse gas but pretty toxic in its own right)"

CO is an important chemical precursor and a fuel, since it retains 75% of the potential combustion energy of the carbon. It's not meant to be released into the atmosphere - that would be an absolute waste. Another shift reaction with hydrogen turns it into other fuels and chemicals, or it can be used to reduce iron oxide, which produces CO2 and plain iron etc.

Burning carbon or CO cost-effectively using metal oxides means capturing the resulting CO2 is vastly cheaper, as it isn't diluted by 80% nitrogen from the atmosphere, which makes it cheap to sequester or use for producing synthetic fuels.

The chemicals and synthetic fuels part is the one that makes it emit less CO2, because it displaces other fossil sources for those chemicals.

The same technology can eventually be used with non-fossil carbon sources to synthesize clean fuels.

Jan 02, 2018

"The same technology can eventually be used with non-fossil carbon sources to synthesize clean fuels."

@Eikka: Very important point. This technology could not only be a bridge technology while humanity transitions away from fossil fuels, but it could also be a way to use biomass as a carbon-negative fuel. In the very possible event that humanity isn't able to prevent global warming from going too far, carbon-negative technology might become crucial.

Jan 03, 2018
"CO is an important chemical precursor and a fuel, since it retains 75% of the potential combustion energy of the carbon"

If you use it as a precursor for fuel you'll combust that eventually and release it as CO2 into the atmosphere. Where exactly is the net gain in CO2 balance, here?

They are pulling excess carbon out of the ground and making more CO2 - just not at their stage of the process.

Jan 03, 2018
"Where exactly is the net gain in CO2 balance, here?"

It's a double use of the carbon. The idea is that 99% of the CO2 can be captured, while displacing other fossil fuels and chemicals, which saves from emitting CO2 from other sources, which is a net reduction in CO2 output.

For example, if you synthesize plastic for a bottle, and then dispose of it in an incinerator using the same metal oxide combustion technology, you capture the CO2 and displace the oil normally used to make the plastic.

There's a side stream of hydrogen from renewable sources to convert the CO into synthetic fuels and chemicals, in case you're wondering where the energy comes from.

Jan 03, 2018
I would like to know how much of the original energy is wasted by this process. To reduce iron oxide it takes a lot of heat since you still have to seperate the CO2 bonds. They do not mention anything about using the heat produced when the iron is again oxidized to renew the cycle. Converting coal to gasoline is great just as long as energy that could be making electricity is not squandered.

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