A paper recently published in Nature Energy based on pioneering research done at Illinois Institute of Technology reveals a promising breakthrough in green energy: an electrolyzer device capable of converting carbon dioxide into propane in a manner that is both scalable and economically viable.
As the United States races toward its target of net-zero greenhouse gas emissions by 2050, innovative methods to reduce the significant carbon dioxide emissions from electric power and industrial sectors are critical. Mohammad Asadi, assistant professor of chemical engineering at Illinois Tech, spearheaded this groundbreaking research.
“Making renewable chemical manufacturing is really important,” says Asadi. “It’s the best way to close the carbon cycle without losing the chemicals we currently use daily.”
What sets Asadi’s electrolyzer apart is its unique catalytic system. It uses inexpensive, readily available materials to produce tri-carbon molecules – fundamental building blocks for fuels like propane, which is used for purposes ranging from home heating to aviation.
To ensure a deep understanding of the catalyst’s operations, the team employed a combination of experimental and computational methods. This rigorous approach illuminated the crucial elements influencing the catalyst’s reaction activity, selectivity, and stability.
A distinctive feature of this technology, lending to its commercial viability, is the implementation of a flow electrolyzer. This design permits continuous propane production, sidestepping the pitfalls of the more conventional batch processing methods.
“Designing and engineering this laboratory-scale flow electrolyzer prototype has demonstrated Illinois Tech’s commitment to creating innovative technologies. Optimizing and scaling up this prototype will be an important step toward producing a sustainable, economically viable, and energy-efficient carbon capture and utilization process,” says Advanced Research Projects Agency-Energy Program Director Jack Lewnard.
This innovation is not Asadi’s first venture into sustainable energy. He previously adapted a version of this catalyst to produce ethanol by harnessing carbon dioxide from industrial waste gas. Recognizing the potential of the green propane technology, Asadi has collaborated with global propane distributor SHV Energy to further scale and disseminate the system.
“This is an exciting development which opens up a new e-fuel pathway to on-purpose propane production for the benefit of global users of this essential fuel,” says Keith Simons, head of research and development for sustainable fuels at SHV Energy.
Illinois Tech Duchossois Leadership Professor and Professor of Physics Carlo Segre, University of Pennsylvania Professor of Materials Science and Engineering Andrew Rappe, and University of Illinois Chicago Professor Reza Shahbazian-Yassar contributed to this work. Mohammadreza Esmaeilirad (Ph.D. CHE '22) was a lead author on the paper.
This could be really big. Propane is a very stable and relatively dense fuel that operates well at both high and low temperatures. We many functioning systems to store, transport, and consume propane in residential, commercial, and industrial capacities.
Assuming the catalyst consumption isn’t prohibitive or the byproducts toxic, this would be a great application for energy storage to use for excess solar or wind power generation. Will we see propane “peaker plants” spring up next to large solar or wind generation sites to ramp up when solar or wind production falls?
Well, that’s a nice way to produce propane, but what should we do with it? Burn it and release the CO2 back into the atmosphere? The other option would be to bury it deep underground in order to reduce the amount of carbon in the atmosphere.
However, if you use it as a part of grid energy storage, then you would need to capture the CO2 again right at the source. That might make sense too.
The idea is to use it like a battery.
If you use some green or otherwise efficient process to fix CO2 into propane, so what if you turn it back into CO2. You’ve just used it to store energy, and you’re carbon neutral (except for the energy generation itself).
Yeah, the question is the efficiency. If it’s not outrageously bad, it could be used as a very long term storage option.
They say very easily that it is economically viable, but I don’t see any proof or even calculations of this. It’s a nice discovery to be sure, but this kind of journalism is not the best way to communicate to the people.
What’s the efficiency? That’s a big question for the energy cost of the system. If it only takes 50% more energy than it stores chemically, that’d be pretty good. But if it’s 5 or 10 times as much, it starts getting really expensive really quick. Sounds interesting, I hope they can develop and refine it!
But if it’s 5 or 10 times as much, it starts getting really expensive really quick.
Even at that level of inefficiency it still may be worth it. Imagine scenarios where electricity is absolutely free, but localized at a place it can’t be used for anything at the time it is available. This happens a lot in energy generation scenarios. Even with old school fossil fuel plants there are thresholds of generation capacity they cannot go below because of limits of the generation process or business requirements of time to spin up to higher levels of generation. For renewables, think about a VERY sunny or windy day where there is so much electricity generation that the power lines are not capable of carrying it all to places of consumption.
Under these conditions electricity is literally thrown away unused. Imagine instead if these catalyzers were available on-site (to remove the electricity transport requirement). Spare juice could be shunted over and Propane created. and stored in regular cheap tanks. Further, a propane burning generator can be located right next to the tanks. In periods of low electricity generation from wind/solar/coal, the generator can be fired up and dump the stored propane onto the power grid at peak consumption times as electricity.
Absolutely, but you’d be competing with hydrogen too. There are ideas to do the same thing with hydrogen, and I think it’s round trip efficiency is higher than that. But it probably also greatly depends on how much the infrastructure costs.
Hydrogen is pretty horrible to deal with. Its density is VERY low which means HUGE tanks to store it in, unless you liquefy it meaning all the energy to bring it down to and maintain it at cryogenic temps which is very energy intensive. The molecule is also tiny so it leaks very very easily.
If you want round trip efficiency higher than 30% you need prohibitive quantities of platinum and iridium (with some promising research to maybe replace the iridium with cobalt, making fuel cells about as sustainable as NMC batteries).
Storing it is also generally prohibitive. Small high pressure vessels have a hard expiry date shorter thna the expected life of a battery, take up more space and cost as much as LFP batteries. By the time you add a fuel cell stack and buffer battery there’s not really any weight saving either.
Geologic storage is an option, but use cases are limited. Large scale stationary tank storage is also a possibility for industrial chemical use.
Hydrogen hype is largely a greenwashing and delay tactic by the oil and gas industry.
PV energy in low cloud areas is <2c/kWh and dropping 7-10% p.a (a recent UAE ppa was 1.6c).
Crude oil is presently ~4c/kWh and frequently 6c. Distillates are often over $1/L before taxes or 10c/kWh.
20% one-way energy efficiency competes with oil. If the catalyst stack is significantly cheaper than water electrolysers it can use curtailed renewables and compete with oil at <10%.
Won’t replace batteries or electrification, but a solid choice for emergency storage or high capital, low-use assets (like a forklift that gets used twice a week or a bbq).
>50% efficiency would displace fossil gas with sufficiently cheap catalyst stack.
