So I was reading about carbon capture, and about how one of the biggest problems with using it to save the planet from global warming is that at the moment it takes bulky infrastructure that’s power hungry and it doesn’t really generate a useful product when captured, which means it’s not really economically viable at the moment.
Something that occurred to me is the principle of biomimicry. We know of a chemical reaction that uses the energy of ambient sunlight to capture CO2 and store energy, all on an energy budget and using only common minerals found in natural soil – photosynthesis. So clearly it is physically possible to find a chemical reaction that can harness CO2 on an energy budget.
I tried to look into the matter and it does seem like there’s some research into duplicating this process, or creating a process inspired by photosynthesis, for use in artificial systems. But it seems to be very expensive, rely on rare elements, and capture little energy. My question is – what’s the big hurdle in this field? How come a photosynthetic algae cell can figure this out but our best chemists can’t replicate it outside of that cell?
The problem is that plants capturing CO2 is not all that efficient. It also doesn’t leave the CO2 in a state suitable for depositing it long term.
Take those algae for instance. If we tried to just use algae for carbon capture we’d need to collect them from a huge volume of water, then dry them, possibly extract all the important chemicals we don’t want to remove from the cycle, such as phosphates, and then we’d have carbon we could sequester.
Simplifying that and still have a system that is robust in the way natural algae growth is, just isn’t all that easy.
Even if there were such a thing, what’s to stop us from just burning up the newly sequestered carbon? If we really wanted to we could set aside large areas to grow some rapid growing trees, pines or something similar. We could then cut them all down, store the wood in some large warehouses, rinse, and repeat. But people would get upset and ask why just let all that good wood sit there and go to waste.
Photosynthesis is membrane bound, with embedded proteins passing different molecular steps in the process along to each other. And some steps involve creating a proton gradient that crosses the membrane. It can’t be done in a vat of loose goo.
You got it in one. With one additional caveat that the primary enzymes to bind and sequester CO2 to start its journey to carbohydrate have between 15 and 4000 (depending upon how strongly you believe in Near Attack Conformation vs. Transition State theories) specific interactions to exquisitely hold that CO2 at the ideal active site… and then it’s still a terribly inefficient reaction. Man made catalysts are incredibly simple by comparison and when put into an atmospheric environment want to react preferentially with O2, H2O, etc. compared to boring old low energy CO2.
Remember that O2 has lots of energy to burn fucking metal (oxidize) whereas CO2 is the final low energy product. Also remember that O2 is 20% of the atmosphere compared to CO2’s 400ppm or 0.04%. So every imagineable physical metric is stacked against CO2 use. When you do the calculation that we are burning well over a 1,000,000 years of stored carbon every year, you can begin to understand why CO2 levels are going up!!!