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My background is in chemical engineering, but I'm now the co-founder of a cleantech software company. Carbon capture is a shim that will never be efficient beca

by diafygi 10y ago

My background is in chemical engineering, but I'm now the co-founder of a cleantech software company. Carbon capture is a shim that will never be efficient because of chemical and thermodynamic limitations that cannot be shortcut, though possibly it will still be required to meet carbon emission goals. Fossil fuel is literally carbon captured CO2 that has been buried in the ground for millions of years, which we pull up and burn for a positive yield, so reversing that process is physically a negative yield. Carbon capture is basically the equivalent of running nested virtual machines. Say you're running Ubuntu 16.04 inside VMware, which is running on Windows 10, which itself is running inside VirtualBox on a Ubuntu 16.04 host. You still can do the things you need inside that inner Ubuntu system, but there's a ton of overhead, and you already have Ubuntu running as the top host. The only reason you'd do that is if the Windows VM was your starting point, you were still running many native apps in Windows, and you need to get the Ubuntu app working yesterday. This is basically the equivalent to carbon capture. We've built a ton of infrastructure off of pulling it out and burning it for energy, so until we port all of that infrastructure over to non-carbon sources (internal combustion-->EVs, coal-->nuclear/solar/wind, etc.), we're basically stuck inside an intermediate system. Unfortunately, the planet is warming so quickly that we have to consider booting another VM to shim some fixes now while we port everything over.

bhickey 10y ago
> reversing that process is physically a negative yield. How energetically costly is direct atmospheric gas capture? Does sequestering flue gases look much better?
- diafygi 10y ago
  Well, from an engineering point of view, energetic cost of capture is one the inputs, not the end goal. Overall cost per unit capture is the end goal. So high energetic costs can be offset by low manufacturing costs if it results in a net overall lower cost. Anyway, yes, direct atmospheric capture is much much more energetically costly than flue gas capture. CO2 in air is 0.04% and in flue gas is 8-15%. Depending on the capture technology and the storage medium, you don't have to build nearly as much infrastructure if you tap into the 8-15% CO2 flue gas stream. Atmospheric carbon capture is literally what plants do, and the manufacturing costs for them is basically plant seeds...done. Or hell, they do that naturally anyway, so it's really just stop-clearing-forests and you've gotten your carbon capture for free. So even though atmospheric carbon capture is way more energetically costly, the manufacturing costs are basically zero, and plants are currently the cheapest solution. That doesn't stop lots of research going into trying to find something better. We found cheaper solar energy with silicon over plants (cost per watt on the grid from photovoltaics is less than biomass), so we may find something cheaper than plants for carbon capture, too.

by diafygi 10y ago

bhickey 10y ago

> reversing that process is physically a negative yield. How energetically costly is direct atmospheric gas capture? Does sequestering flue gases look much better?

diafygi 10y ago
Well, from an engineering point of view, energetic cost of capture is one the inputs, not the end goal. Overall cost per unit capture is the end goal. So high energetic costs can be offset by low manufacturing costs if it results in a net overall lower cost. Anyway, yes, direct atmospheric capture is much much more energetically costly than flue gas capture. CO2 in air is 0.04% and in flue gas is 8-15%. Depending on the capture technology and the storage medium, you don't have to build nearly as much infrastructure if you tap into the 8-15% CO2 flue gas stream. Atmospheric carbon capture is literally what plants do, and the manufacturing costs for them is basically plant seeds...done. Or hell, they do that naturally anyway, so it's really just stop-clearing-forests and you've gotten your carbon capture for free. So even though atmospheric carbon capture is way more energetically costly, the manufacturing costs are basically zero, and plants are currently the cheapest solution. That doesn't stop lots of research going into trying to find something better. We found cheaper solar energy with silicon over plants (cost per watt on the grid from photovoltaics is less than biomass), so we may find something cheaper than plants for carbon capture, too.