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Sounds interesting - Do you have a link for that, or if you've got time could you explain?

by bopbop 8y ago

semi-extrinsic 8y ago
There's a lot of literature on this; Wikipedia has a decent starting point: https://en.wikipedia.org/wiki/Carbon_sequestration#Geological_sequestration https://en.wikipedia.org/wiki/Carbon_sequestration#Geologica... TL;DR: if you compress CO2 to above 73 bar, it becomes supercritical fluid, which has a density almost like water and which does not mix with water. If we inject this fluid into underground saline aquifers, we can trap it indefinitely. Basically exactly the reverse of producing oil and gas. In this case you're transporting and injecting pure CO2, not water with 0.1% - 1% CO2. It's been done at large scale since the mid-1990s, so we know it's viable. Lots of research and development on details/optimization still to be done, but we know it will work and we know we can scale it up.
- rthomas6 8y ago
  Could we combine this with some kind of carbon capturing process to reduce existing CO2 in the atmosphere?
  - semi-extrinsic 8y ago
    Long term, yes, that's exactly the plan. Short-term, it's going to be CO2 captured from large emission sites - powerplants, chemical processing industry, cement and steel factories etc. Just because the CO2 concentration is so much higher in exhaust/flue gas, 10-40% versus 0.04% in the atmosphere, it's much more cost effective in the next 50-ish years.
  - Timmah 8y ago
    In another thread today it was pointed out that humans produce 50 gigatonnes of CO2 per year. We have to start somewhere, but grabbing a few tons at a time may not out much of a dent in the problem.
- deleted 8y ago
  [deleted]
- Timmah 8y ago
  How is it contained in the earth? Wouldn't the pressure eventually escape, either by rupturing its container or seeping through the earth?
  - semi-extrinsic 8y ago
    Same way as oil and gas has been contained for hundreds of millions of years: there is an impermeable caprock that contains the reservoir/aquifer. In many cases, aquifers are so huge that injecting even a few million tonnes of CO2 makes only a small difference in pressure. And if the pressure did increase too much, we would drill a well deep at the aquifer bottom and take out some of the water.

Sounds interesting - Do you have a link for that, or if you've got time could you explain?

by bopbop 8y ago

Sounds interesting - Do you have a link for that, or if you've got time could you explain?

There's a lot of literature on this; Wikipedia has a decent starting point: https://en.wikipedia.org/wiki/Carbon_sequestration#Geological_sequestration https://en.wikipedia.org/wiki/Carbon_sequestration#Geologica... TL;DR: if you compress CO2 to above 73 bar, it becomes supercritical fluid, which has a density almost like water and which does not mix with water. If we inject this fluid into underground saline aquifers, we can trap it indefinitely. Basically exactly the reverse of producing oil and gas. In this case you're transporting and injecting pure CO2, not water with 0.1% - 1% CO2. It's been done at large scale since the mid-1990s, so we know it's viable. Lots of research and development on details/optimization still to be done, but we know it will work and we know we can scale it up.

rthomas6 8y ago
Could we combine this with some kind of carbon capturing process to reduce existing CO2 in the atmosphere?
- semi-extrinsic 8y ago
  Long term, yes, that's exactly the plan. Short-term, it's going to be CO2 captured from large emission sites - powerplants, chemical processing industry, cement and steel factories etc. Just because the CO2 concentration is so much higher in exhaust/flue gas, 10-40% versus 0.04% in the atmosphere, it's much more cost effective in the next 50-ish years.
- Timmah 8y ago
  In another thread today it was pointed out that humans produce 50 gigatonnes of CO2 per year. We have to start somewhere, but grabbing a few tons at a time may not out much of a dent in the problem.
deleted 8y ago
[deleted]
Timmah 8y ago
How is it contained in the earth? Wouldn't the pressure eventually escape, either by rupturing its container or seeping through the earth?
- semi-extrinsic 8y ago
  Same way as oil and gas has been contained for hundreds of millions of years: there is an impermeable caprock that contains the reservoir/aquifer. In many cases, aquifers are so huge that injecting even a few million tonnes of CO2 makes only a small difference in pressure. And if the pressure did increase too much, we would drill a well deep at the aquifer bottom and take out some of the water.