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> The problem with sequestering CO2 as hydrocarbons is that you need to put a whole load of energy (embodied in the hydrogen you're combining it with) into the

> The problem with sequestering CO2 as hydrocarbons is that you need to put a whole load of energy (embodied in the hydrogen you're combining it with) into the ground and leave it there. Why would you be putting energy into the ground? If you're producing hydrocarbons, those will presumably be burned or used for something else (e.g. plastics).

loeg 8y ago
It only removes the carbon from the atmosphere if you don't subsequently burn it.
- tomatotomato37 8y ago
  It burns carbon that was in the air to begin with though. An attempt at a closed loop with gasoline is better than a one way road into the atmosphere
  - loeg 8y ago
    The loop isn't closed — you have to add energy to drive the process.
    - smt88 8y ago
      True, but the new energy could be renewable/clean. In that case, it's like you're using hydrocarbons as a storage and transport mechanism for renewables. Also lets you have nearly net-zero carbon emissions from the billions of hydrocarbon-burning engines in the world.
      - Johnny555 8y ago
        Efficiency still matters -- Renewable doesn't mean unlimited or cheap -- if it takes 10X more energy to create hydrocarbons than you get back from burning them, maybe it's better to use that energy for more efficient transportation storage systems. Then you can use some of the energy saved for direct carbon sequestration.
    - madengr 8y ago
      Yeah, I’d like to know the cycle efficiency.
    - deleted 8y ago
      [deleted]
    - adrianmonk 8y ago
      One of the goals is to close the carbon loop (not the energy loop). Quoting from the paper: > An industrial process for large-scale capture of atmospheric CO2 (DAC) serves two roles. First, as a source of CO2 for making carbon-neutral hydrocarbon fuels, enabling carbon-free energy to be converted into high-energy-density fuels. Solar fuels, for example, may be produced at high-insolation low-cost locations from DAC-CO2 and electrolytic hydrogen using gas-to-liquids technology enabling decarbonization of difficult-to-electrify sectors such as aviation. And second, DAC with CO2 sequestration allows carbon removal. So, to summarize their first role, they would produce hydrogen from water, combine it with CO2 extracted from the atmosphere, and then burn it. Thus no net carbon added to the atmosphere. Essentially, instead of moving carbon from fossil fuels to the atmosphere, you would borrow carbon from the atmosphere, turn it into fuels, burn it, and return it to where you borrowed it from.
    - notabee 8y ago
      This technology is one answer to an often-heard criticism (often presented with dubious motivation). The criticism is that storing solar or wind energy for when the sun isn't shining or the wind isn't blowing is a problem with renewables. However, if one considers intelligent grid balancing, solar-thermal towers, increasingly better battery technology, and this kind of solar-to-hydrocarbon conversion you have plenty of places to put excess renewable power generation.
- User23 8y ago
  Something is going to burn it no matter what. The microbiome considers hydrocarbons food.
  - smt88 8y ago
    But then it has a chance to become biomass for bacteria, plants, and fungi instead of atmospheric CO2.
  - loeg 8y ago
    Sealed containers?
    - JackCh 8y ago
      A new purpose for Yucca Mountain?
  - istorical 8y ago
    No? Coal for example, when buried underground, does not spontaneously re-enter the atmosphere as CO2. Carbon sequestration is a real thing, we just lack either economic or political will to prioritize it. https://en.wikipedia.org/wiki/Carbon_sequestration https://en.wikipedia.org/wiki/Carbon_sequestration
graeme 8y ago
Ideally we'd sequester enough to bring us back down to the 280 ppm we had before we started
- semi-extrinsic 8y ago
  Any realistic plan for that is over a century away. By now, it will take luck and hard work to achieve even the 2 degree scenario (2DS), where we have cut net emissions by 60% in 2050 and we reach zero net emissions some time in the 2060s-2070s. Forget about reaching 280 ppm, if we can stabilize at 450 ppm by 2100 it'd be a huge achievement.
  - graeme 8y ago
    Sure, but they asked why we would put energy in the ground. To get back to 280 eventually, is why.

loeg 8y ago

It only removes the carbon from the atmosphere if you don't subsequently burn it.

tomatotomato37 8y ago
It burns carbon that was in the air to begin with though. An attempt at a closed loop with gasoline is better than a one way road into the atmosphere
- loeg 8y ago
  The loop isn't closed — you have to add energy to drive the process.
  - smt88 8y ago
    True, but the new energy could be renewable/clean. In that case, it's like you're using hydrocarbons as a storage and transport mechanism for renewables. Also lets you have nearly net-zero carbon emissions from the billions of hydrocarbon-burning engines in the world.
    - Johnny555 8y ago
      Efficiency still matters -- Renewable doesn't mean unlimited or cheap -- if it takes 10X more energy to create hydrocarbons than you get back from burning them, maybe it's better to use that energy for more efficient transportation storage systems. Then you can use some of the energy saved for direct carbon sequestration.
  - madengr 8y ago
    Yeah, I’d like to know the cycle efficiency.
  - deleted 8y ago
    [deleted]
  - adrianmonk 8y ago
    One of the goals is to close the carbon loop (not the energy loop). Quoting from the paper: > An industrial process for large-scale capture of atmospheric CO2 (DAC) serves two roles. First, as a source of CO2 for making carbon-neutral hydrocarbon fuels, enabling carbon-free energy to be converted into high-energy-density fuels. Solar fuels, for example, may be produced at high-insolation low-cost locations from DAC-CO2 and electrolytic hydrogen using gas-to-liquids technology enabling decarbonization of difficult-to-electrify sectors such as aviation. And second, DAC with CO2 sequestration allows carbon removal. So, to summarize their first role, they would produce hydrogen from water, combine it with CO2 extracted from the atmosphere, and then burn it. Thus no net carbon added to the atmosphere. Essentially, instead of moving carbon from fossil fuels to the atmosphere, you would borrow carbon from the atmosphere, turn it into fuels, burn it, and return it to where you borrowed it from.
  - notabee 8y ago
    This technology is one answer to an often-heard criticism (often presented with dubious motivation). The criticism is that storing solar or wind energy for when the sun isn't shining or the wind isn't blowing is a problem with renewables. However, if one considers intelligent grid balancing, solar-thermal towers, increasingly better battery technology, and this kind of solar-to-hydrocarbon conversion you have plenty of places to put excess renewable power generation.
User23 8y ago
Something is going to burn it no matter what. The microbiome considers hydrocarbons food.
- smt88 8y ago
  But then it has a chance to become biomass for bacteria, plants, and fungi instead of atmospheric CO2.
- loeg 8y ago
  Sealed containers?
  - JackCh 8y ago
    A new purpose for Yucca Mountain?
- istorical 8y ago
  No? Coal for example, when buried underground, does not spontaneously re-enter the atmosphere as CO2. Carbon sequestration is a real thing, we just lack either economic or political will to prioritize it. https://en.wikipedia.org/wiki/Carbon_sequestration https://en.wikipedia.org/wiki/Carbon_sequestration

graeme 8y ago

Ideally we'd sequester enough to bring us back down to the 280 ppm we had before we started

semi-extrinsic 8y ago
Any realistic plan for that is over a century away. By now, it will take luck and hard work to achieve even the 2 degree scenario (2DS), where we have cut net emissions by 60% in 2050 and we reach zero net emissions some time in the 2060s-2070s. Forget about reaching 280 ppm, if we can stabilize at 450 ppm by 2100 it'd be a huge achievement.
- graeme 8y ago
  Sure, but they asked why we would put energy in the ground. To get back to 280 eventually, is why.