So I found this online:
It looks like a double edged sword. On one hand, it could advert climate change. On another hand, it could improve feedstock prices (less corn usage for ethanol)- what do you guys think about this article?
I’m curious as to how well it could be scaled up. Would it be possible (or remotely practical) to build a huge facility that pairs a lot of these air-scrubbing ethanol-makers with a nuclear power plant?
I didn’t see in the article a mention of the concentration of CO2 needed. If it needs a high concentration then it may take too much energy to concentrate the CO2 from the atmosphere to be viable. Alternatively, if people exploit non-atmospheric sources of CO2, it would be at most carbon-neutral, and could harm the environment as people create CO2 explicitly for this process, and then possibly leak some of it.
In their conclusions with my bolding:
I don’t see how. It uses huge amounts of energy to convert CO2 to ethanol. Where does that energy come from? If it’s nuclear power, then OK it’s carbon-negative, but you still have the question of what you’re planning to do with that ethanol. If you’re burning it for fuel, then you’re just dumping that CO2 right back into the atmosphere.
Understand that what they’re saying isn’t a way to turn CO2 into ethanol for free; it takes lots of energy, in the form of electricity, and then that ethanol would be converted back to CO2 when it’s used as fuel.
I seem to recall a process where CO2 can cause plants to grow, which we then ferment to make, you know, ethanol.
Direct air capture of CO2 is indeed energy intensive, given that we’re talking 400 ppm. The one CO2-to-liquids plant that exists uses CO2 from a geothermal steam stream.
CO2 is often removed from biogas prior to combustion, and is concentrated in the exhaust.
So there are plenty of less-dilute-than-air CO2, but I haven’t added them up.
You just described a (roughly) carbon-neutral process subbing for our current very carbon-positive fuel practices, but you “don’t see how”?
I think his point is that you could more efficiently use that nuclear energy to cut carbon out of the cycle in other ways. For example, use the electricity to power 10 electric cars instead of creating the ethanol needed to power 1 internal combustion car. Both processes end up carbon-neutral, but one has a much bigger impact. The less efficient the electricity-to-ethanol step is, the more benefit you get from skipping it.
You’d be burning (total WAG) 100 gallons of ethanol to generate the energy to convert the exhaust from burning 1000 gallons of whatever into 2 gallons of ethanol.
Then you need to get another 98 gallons of ethanol from someplace else to go around the process loop again.
There’s not going to be a chemical perpetual motion machine any more than there’s going to be a mechanical one.
The problem with CO2 is that in terms of the fuel cycle it’s ash. It’s what’s left over after you’ve pulled the energy out of the upstream chemicals. To make it into fuel again (of whatever type), you need to inject more energy back into it.
If you assume a functionally infinite supply of free no-carbon electricity from solar, nuclear, wind, etc., then this *might *be a way to create carbon-neutral liquid fuels for portable (= transportation) use.
What do plants do with it then?
There’s already biotechnology to turn CO2 into ethanol. You arrange rows of biocollections devices to absorb the CO2 and convert it into starch and sugar which is collected and then converted to ethanol by tiny biodevices. I guess it’s got a few more steps, but it’s working.
One option is using the variable energy production of wind or solar to power CO[sub]2[/sub] to ethanol. Not ideal, but it is a means to level out the peaks and valleys of such renewable energy production. This could allow a steady renewable input to the grid with excess power diverted to ethanol production.
Plants are using solar energy, basically, to convert the CO2 into higher-energy compounds like sugars.
That’s one benefit for this sort of technology. Another is moving energy over large distances; piping a liquid is more efficient than pushing electrons. Similarly you have situations like Iceland where they have more electrical generating capacity than they need. You can put alcohol (or other liquids) on a ship. They’re already doing this.
Also, for vehicles, liquid fuels are superior in terms of energy density and refueling time. You can get away with batteries on the twee vehicles we currently have on the market. It doesn’t work so well for class 8 trucks. Yet. Maybe they’ll be better down the road. Maybe we’ll still want liquid fuels made from carbon from the air recently rather than millions of years ago. It’s good to have options.
Now, do our friends at ORNL have all the kinks worked out? Not by a long shot.
Inject more energy back into it. Just as I said. Using solar power that they collect with their chlorophyll and other chemistry.
Our real problem as a society is that almost any closed-loop mechanism, bio-based or human-engineering-based is going to be inherently less efficient than simply burning fossil fuel. As long as you ignore where the energy in the fossil fuel came from and ignore the externalities of oil production and oil combustion.
As long as we can look ourselves in the mirror as a society and pretend those other things are costless and therefore infinitely efficient, we’ll continue to believe that oil is both cheaper and better. It isn’t really of course, but as Obi-Wan might say: the power of wishful thinking is strong in that one.
Agree.
The snippet posted in the OP makes it sound like there’s a way to not only get free energy but to suck CO2 out of the atmosphere while doing it. You have to dig into the details to find out that it’s energy-neutral at best, and that the carbon sucked out will be released again when that ethanol is burned.
Sure it’s an interesting alternative to electric cars, but I just wanted to point out that it’s not what it might seem at first.
“Dig in”, as in “read all the words”?
[QUOTE=Straight from the OP]
This means that this conversion process could be used as temporary energy storage during a lull in renewable energy generation, smoothing out fluctuations in a renewable energy grid. “A process like this would allow you to consume extra electricity when it’s available to make and store as ethanol,” said Rondinone. “This could help to balance a grid supplied by intermittent renewable sources.”
[/QUOTE]
If you read their conclusion in their paperit not going to be economically viable but their approach opens avenues that could be profitable.