Energy

New catalyst rearranges carbon dioxide and water into ethanol fuel

New catalyst rearranges carbon...
Artist's rendering of electrocatalytic process for conversion of carbon dioxide and water into ethanol
Artist's rendering of electrocatalytic process for conversion of carbon dioxide and water into ethanol
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Artist's rendering of electrocatalytic process for conversion of carbon dioxide and water into ethanol
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Artist's rendering of electrocatalytic process for conversion of carbon dioxide and water into ethanol

Researchers at the US Dept of Energy's Argonne National Laboratory, working with Northern Illinois University, have discovered a new catalyst that can convert carbon dioxide and water into ethanol with "very high energy efficiency, high selectivity for the desired final product and low cost."

The catalyst is made of atomically dispersed copper on a carbon-powder support, and acts as an electrocatalyst, sitting in a low voltage electric field as water and carbon dioxide are passed over it. The reaction breaks down these molecules, then selectively rearranges them into ethanol with an electrocatalytic selectivity, or "Faradaic efficiency", higher than 90%. The team says this is "much higher than any other reported process."

Once the ethanol is created, it can be used as a fuel additive, or as an intermediate product in the chemical, pharmaceutical and cosmetics industries. Using it as a fuel would be an example of a "circular carbon economy," in which CO2 recaptured from the atmosphere is effectively put back in as it's burned.

If the process is powered by renewable energy, which the researchers say it can be due to its low-temperature, low-pressure operation and easy responsiveness to intermittent power, then great; all you're losing is fresh water, which is its own issue.

Realistically, you're still a lot better off running an EV than a car fueled with gasoline using this ethanol as an additive. While its Faradaic efficiency might be excellent, its overall electrical efficiency won't be; putting the same amount of energy into a battery will get more power to the wheels at the end of the day, because combustion engines are horribly inefficient in comparison to electric powertrains, and there will be additional significant power losses at this catalysis stage, as well as the industrial carbon capture and transport stages.

There's no way of telling at this stage what the costs might be, either. There are already a number of synthetic fuels using catalytically captured carbon dioxide; Carbon Engineering is one firm that pulls CO2 from the air to create a synthetic crude that can be refined into high-purity aviation fuel, for example.

Such synthetic fuels need to compete with regular fossil gasoline on price, so without knowing how the Argonne team's carbon-capture ethanol competes with bioethanol and other sources there, it's hard to place this on the spectrum between "neat result that won't see wide scale use" and "environmentally significant discovery."

The paper is published in Nature Energy.

Source: Argonne National Laboratory

14 comments
Brian M
As an intermediate stage for reducing use of non-renewables or cutting out the production of ethanol from agricultural methods (read bad for the environment and food production) it would be great if it was scaled up to a usable system. Maybe ethanol or a a substance derived (more energy/l) from it could be used as a 100% fuel to replace petrol?
Elgiantpopcorn
It's nice to see biofuels production advances!
Saying that one's better off putting the energy into a battery is only considering the raw power though.
Building a battery in itself is an extremely resource-intensive (a lithium-ion battery can only give back 2.5 times of the energy invested to create it in its whole life) and requires rare metals that are often (~50%) mined in China in heavy-processes that pollute a lot. And we are expected to run out of them in a near future. Producing biofuel with recyclable/abundant materials while pumping CO2 from the atmosphere beats using batteries by a fair margin IMO.
Pablo
Terrific idea, but I'd bet it'll never get to a production level as long as we're producing Ethanol by massively subsidizing corn crops. All those billions get soaked up by huge corporations with armies of Lobbyists in DC... If the value of removing carbon from the atmosphere were somehow quantified and figured in, there might be a far better ROI even with the electrical consumption of the process. Ethanol as we produce it now is hideously inefficient, costing nearly a gallon of diesel per gallon of product. The only beneficiaries are the manufacturers and to a lesser degree, the farmers.
Catweazle
In point of fact, when the conversion losses involving the rectifiers, transformers, inverters, battery inefficiencies and network transportation losses the efficiency of EVs is nowhere near as great as the enthusiasts would have us believe. When you take into account the environmental costs of the construction and recycling of the batteries and the rare earth elements necessary for the motors and electronics, plus the extra contamination caused by the increased tyre and brake wear caused by the increase in weight of EVs compared to fossil fuelled vehicles, the advantages become even less. EVs are nowhere near the panacea they are cracked up to be.
paul314
Taking CO2 out of the atmosphere would be a good thing, and ethanol is also useful as a feedstock for many other chemicals.
michael_dowling
There is already too much CO2 in the atmosphere,which is why we have climate change,so using this technology just recycles it,and does not remove it permanently from the air. What we need is something to lock up the atmospheric CO2 into something that will not get back into the air. One idea is enhanced rock weathering,which involves spreading rock dust on croplands. Farmers already do something similar to improve the soil,so spreading rock dust would be straightforward. https://phys.org/news/2020-07-croplands-absorb-billion-tonnes-co2.html
jerryd
Running cars is not the future use for ethanol but as a backup fuel running CHP at 80% efficient supplying heat, power in winter. So just change those efficiency numbers and making this very good news.
You can make near pure CO2 and water from burning biomass in O2 making power too , O2 made from electrolyzing water into O2 and H2 at about 80% efficient as using both products.
So now you have efficient CO2 and add some more water and if this catalyst is 90% efficient, earlier ones were just 60% your overall efficiency is around 70% plus the H2 which also can be used to make heat, power at 80% efficiency.
So overall conversion to products needed is very good in the 80% range.
On corn ethanol is provides far better food than corn, a terrible food is. The mash from making ethanol is high quality protein plus corn oil, plastic feedstock and a lot of silage this ethanol, power and heat can be made from.
So stop believing big oil, auto's anti ethanol lies and being a tool for them to get rid of their competition and burn more oil instead.
jerryd
Making batteries is far more efficient than Elgiant says and another example of big oil lies. While it does take a lot of energy as li-ion does now it stores 10k cycles vs only 80 cycles to pay it's energy debt.
And does take into account it takes 3kwh to make a gal of gasoline as just the start of the energy to make oil and only 7% of the energy from the oil well to move the car vs 75% from solar, wind in and EV.
So a battery is 80% more efficient that oil overall.
And that is coming way down with Tesla's new dry process and other battery types like LiFe, LiS, metal/air, sodium, other couples.
guzmanchinky
Progress is always good to see, even if we don't know for sure how economically viable it is. Sometimes these are the shoulders that some other scientist stands on to save the planet...
Tim Woolford
"a lithium-ion battery can only give back 2.5 times of the energy invested to create it in its whole life" - I am almost certain this is false. Can you please cite where you got this data from?