r/science • u/Wagamaga • Aug 06 '20

Chemistry Turning carbon dioxide into liquid fuel. Scientists have discovered a new electrocatalyst that converts carbon dioxide (CO2) and water into ethanol with very high energy efficiency, high selectivity for the desired final product and low cost.

https://www.anl.gov/article/turning-carbon-dioxide-into-liquid-fuel
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u/Mrhorrendous Aug 06 '20

This process will require more energy than just continuing as we are now. To power it with renewables would require more renewable energy than if we had just gotten rid of gas cars in the first place. There are easier ways to produce carbon neutral cars.

If X percentage of our energy use is gas cars, we still need to produce enough gasoline to meet that demand of X. But to produce this fuel, we have to input an amount of energy equal to X*Y, where Y is the inverse of the efficiency of the process, and due to the thermodynamics of the process, will always be >1.

This is really just a way to continue using gasoline after we've converted the rest of our power grid to renewables. I guess I'd hope that by then we stop using gas cars, which are pretty inefficient compared to other types of "power plants". This process also produces some byproducts which is not great.

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u/supergeeky_1 Aug 06 '20

There are processes that take a higher energy density than we currently have available in batteries. Things like heavy haul trucks, airplanes, trains, and cargo ships. This would allow those to be carbon neutral. If we can use a process like this to create an energy dense fuel with “extra” energy from green generation methods then we can burn it where needed or use it in more traditional gas turbine power plants for the times that renewables aren’t meeting demand.

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u/BoilerPurdude Aug 06 '20

I mean Trains shouldn't need batteries at all. They are on a track we can find a way to transfer electricity to them directly if we really wanted to.

Additionally ethanol isn't that energy dense. More so than batteries but less than gasoline and way less than jet fuel.

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u/anti_dan Aug 07 '20

People way overrate ethanol as a fuel. Its not dense and its corrosive. Really bad for most cars even at the 5 or 10% mixes some states require.