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Are we closer to CO2 sequestration than a working fusion reactor?

njarboe 9y ago
Both technologies can "work" right now (5-10 yr design and construction time). The trick is getting the economics to "work" within even an order of magnitude. Source: I'm a geologist and my dad is a plasma physicist researching fusion power.
- ouid 9y ago
  the upfront cost to clean coal is very large, but it reduces the usable energy by less than 30%. That's much less than an order of magnitude, especially given how cheap it is to burn coal. Upfront costs also generally go down over time. The infrastructure required to perform carbon sequestration is extremely nascent. There's a lot of specialty equipment, and drilling to sufficient limestone deposits. These things will scale well though. Especially with government funding.
  - njarboe 9y ago
    Not sure what you mean exactly by "up front costs" but yes, the capex and time to production for a complete clean coal power plant system or a functioning fusion power plant is what would make producing energy by those methods many times more expensive than natural gas or solar. Maybe if power companies can finance at negative interest rates, like some counties are doing, the high capital costs become a positive rather than a negative and all sorts of schemes are possible.
    - ouid 9y ago
      Natural gas requires the same upfront costs to scrub CO2 out of the exhaust for. In particular, it requires CO2 scrubbers. The most efficient place to capture carbon dioxide in the atmosphere is before it enters the atmosphere. Therefore, any attempt to lower the amount of carbon in the atmosphere should necessarily start with removing the carbon dioxide from exhaust. All fossil fuel plants should have scrubbers, it is by far the most cost effective measure that we can take to dramatically reduce increases to atmospheric CO2. The argument that "clean coal is no coal" is assuming that there should be no similar requirement on natural gas.
      - njarboe 9y ago
        The capital costs for setting up scrubbing CO2 from a natural gas plant may be similar to coal but you get about twice as much energy per amount of CO2 from natural gas as you do from coal. Sequestering 1/2 the amount of carbon should cost quite a bit less in energy and dollars. Reducing the amount of CO2 release into the atmosphere definitely should be a high priority and a carbon dioxide release tax is probably the best way to do that. Another thing about natural gas that makes it better than coal is that the hydrogen in natural gas reacts with oxygen in the atmosphere to form water. This actually reduces the total amount of the atmospheric gas and therefor reduces the greenhouse effect. I have yet to find a scientific paper that describes the magnitude of this effect and I haven't found where this phenomenon is taken into account in climate models. Most people don't realize that the pressure of the atmosphere at the surface is a more important factor for "greenhouse effect" heating than its composition. The surface of Venus is so hot not mostly because of the high % of CO2 in the atmosphere but the surface pressure is 93 bar as compared to Earth's 1 bar.
Robotbeat 9y ago
Yes. But I doubt CO2 capture and sequestration makes any sense with coal. Might work for really efficient natural gas plants which emit half the CO2 per thermal unit of energy and can be made nearly twice as efficient thermodynamically, meaning that for the same unit of electricity, you only need to sequester a third to a quarter of the CO2. ...but still would be incredibly expensive. You're going to be better off with solar, wind, geothermal, hydro, and nuclear in a broad mix with a few hours of grid storage to smooth things over.

Both technologies can "work" right now (5-10 yr design and construction time). The trick is getting the economics to "work" within even an order of magnitude. Source: I'm a geologist and my dad is a plasma physicist researching fusion power.

ouid 9y ago
the upfront cost to clean coal is very large, but it reduces the usable energy by less than 30%. That's much less than an order of magnitude, especially given how cheap it is to burn coal. Upfront costs also generally go down over time. The infrastructure required to perform carbon sequestration is extremely nascent. There's a lot of specialty equipment, and drilling to sufficient limestone deposits. These things will scale well though. Especially with government funding.
- njarboe 9y ago
  Not sure what you mean exactly by "up front costs" but yes, the capex and time to production for a complete clean coal power plant system or a functioning fusion power plant is what would make producing energy by those methods many times more expensive than natural gas or solar. Maybe if power companies can finance at negative interest rates, like some counties are doing, the high capital costs become a positive rather than a negative and all sorts of schemes are possible.
  - ouid 9y ago
    Natural gas requires the same upfront costs to scrub CO2 out of the exhaust for. In particular, it requires CO2 scrubbers. The most efficient place to capture carbon dioxide in the atmosphere is before it enters the atmosphere. Therefore, any attempt to lower the amount of carbon in the atmosphere should necessarily start with removing the carbon dioxide from exhaust. All fossil fuel plants should have scrubbers, it is by far the most cost effective measure that we can take to dramatically reduce increases to atmospheric CO2. The argument that "clean coal is no coal" is assuming that there should be no similar requirement on natural gas.
    - njarboe 9y ago
      The capital costs for setting up scrubbing CO2 from a natural gas plant may be similar to coal but you get about twice as much energy per amount of CO2 from natural gas as you do from coal. Sequestering 1/2 the amount of carbon should cost quite a bit less in energy and dollars. Reducing the amount of CO2 release into the atmosphere definitely should be a high priority and a carbon dioxide release tax is probably the best way to do that. Another thing about natural gas that makes it better than coal is that the hydrogen in natural gas reacts with oxygen in the atmosphere to form water. This actually reduces the total amount of the atmospheric gas and therefor reduces the greenhouse effect. I have yet to find a scientific paper that describes the magnitude of this effect and I haven't found where this phenomenon is taken into account in climate models. Most people don't realize that the pressure of the atmosphere at the surface is a more important factor for "greenhouse effect" heating than its composition. The surface of Venus is so hot not mostly because of the high % of CO2 in the atmosphere but the surface pressure is 93 bar as compared to Earth's 1 bar.

Robotbeat 9y ago

Yes. But I doubt CO2 capture and sequestration makes any sense with coal. Might work for really efficient natural gas plants which emit half the CO2 per thermal unit of energy and can be made nearly twice as efficient thermodynamically, meaning that for the same unit of electricity, you only need to sequester a third to a quarter of the CO2. ...but still would be incredibly expensive. You're going to be better off with solar, wind, geothermal, hydro, and nuclear in a broad mix with a few hours of grid storage to smooth things over.