4 ms·

>always be cheaper to prevent creation of CO2 (burning fossil fuels) than to catch CO2 Why ? Where does this comes from ?

• pjc50 8y ago
  One of those processes emits energy, the other requires energy input - and to overcome the entropy, the capture process requires more energy. Edit: one barrel of oil produces 0.43 metric tons CO2 and costs about $60. Therefore, if your price of CO2 capture is more than $140/ton, it's cheaper to "capture" the CO2 by buying a barrel of oil and "sequestering" it as you would the CO2. So if carbon capture prices are more than about $150 it would be a viable business to operate a "reverse oilfield" buying oil on the open market and pumping it underground.
  • WillPostForFood 8y ago
    Shouldn’t you include the value of the energy that the barrel creates in the calculation?
    • pjc50 8y ago
      It was mostly a piece of elaborate sarcasm about the value of reducing consumption rather than capture. Going down that route, should the value of energy used in carbon capture be counted at the market rate or its opportunity cost? It's valid to point out that the value of a barrel of oil is more than its cost and this gives rise to a "consumer surplus", which leads to the carbon tax arguments. (Although, as Retric points out upthread, there are consequential CO2 side-effects from oil extraction more than just burning it, so maybe those should be counted too?)
  • nicoburns 8y ago
    This might not always be the case if for example solar energy prices keep falling as fast as they have been.
• js8 8y ago
  This is just law of conservation of energy (1st law of thermodynamics). If burning carbon to CO2 produces certain amount of energy (part of which then can be used to do useful work), then the reverse of that process, breaking up CO2 to carbon and oxygen, will require at least the amount of energy that was produced in burning it. So yeah, it's nice to have the technology to take CO2 from the air and create C and O2, however, the catch is, it requires energy. If that energy comes from fossil fuels, you will be better off not to do this thing at all, because you will end up creating a bit more CO2 in the process.
  • DougN7 8y ago
    If the energy to do the reverse is not from carbon fuels (solar, wind) then it gets interesting though, right?
  • mhandley 8y ago
    If we're going to depend on renewables for almost all electricity generation, this will require both energy storage, and installing more renewables than are needed for typical usage. This wouldn't be true if we had cheap energy storage that could supply load for weeks at a time through unusual dips in generation, but that seems unlikely. In practice it's cheaper to install excess generation than excess storage. Now, if you've got excess generation for electricity, then at times of good generation, you want to use that electricity for something, as otherwise the electricity price will be negative. Using it to produce synthetic fuels for aviation seems like a really good match, as that electricity would be effectively free.
  • jbay808 8y ago
    The second law makes it much worse. If you take concentrated oxygen and concentrated carbon (soot), you can burn them in a sealed chamber into pure CO2. If you are very careful about extracting the energy, you might get most of it. But already the entropy has increased, because now the carbon and oxygen have mixed together. Attempting to reverse the reaction will need extra energy to deal with that. It gets much worse though, if you open up our chamber and vent the gas into the atmosphere. The entropy goes through the roof as the CO2 concentration drops to a few hundred PPM, and the cost of reversing the reaction goes up even more.