Carbon Capture is not a solution until nuclear, solar and wind energy are fully deployed.
Carbon Capture on Land
At this writing carbon capture technology is so expensive that only the petroleum industry has deployed it — where the CO2 captured has been used to make natural gas usable and to increase underground oil recovery1. Thus it has had a negative impact on greenhouse emissions. Most carbon capture projects have failed or operated at 50% or less of projected capacity.23
I have not been able to find a reliable and complete analysis of the greenhouse gas impact of carbon capture technology. My own summary analysis, which follows, suggests that the greenhouse gas savings are not worth the huge investments required, so that a better use of financial resources would be to replace fossil fuel power plants with nuclear power plants; or though not as effective, where appropriate, with solar or wind energy backed up by fossil fuels.
The additional energy required to operate carbon capture is, about 30% of a power plant’s output4. I don’t believe this amount includes the fossil fuels used to construct the facility. To this one must add the energy use for transmission and storage of CO2, and to replace some small amount for leakage of the captured CO2. For argument’s sake, assume the total additional energy needed is 35% of a power plant’s output.
Therefore we need another power plant that operates full time and generates the 35%, which I will assume has also carbon capture. So we need to make that up. So we have 1 +.35 + .123+0.043 +0.015 +0.006. = 1.54 power plants needed (the same result as dividing by 0.65%). I assume that only 50% of the CO2 is captured by the power plant since it becomes much more difficult and expensive to capture more.) The system emits 77% of the original emissions, that is, the CO2 savings are only 23%, a terrible result given the cost. Incidentally, methane emissions are increased by 54%!! And, this has a much greater short-run climate warming effect that CO2.
These CO2 emissions are 50 times higher than a new nuclear power plant. They are higher than wind or solar energy backed up by a natural gas combined cycle power plant (without carbon capture) (see my pages on nuclear, wind and solar energy). It is clear that financial resources should be invested in nuclear, and if not, wind and solar power, and not in carbon capture.
Carbon capture on land from the atmosphere will be much more energy intensive than from a power plant, since the CO2 is far less concentrated. Only when nuclear, wind and solar power has completely replaced fossil fuel and wood power will it make sense to use these same sources to power carbon capture.
Carbon capture by the Ocean
Seaweed and phytoplankton have been suggested as means to remove CO2 from the atmosphere. Presently we emit about 37 billion tons of CO2 per year. Presently seaweed removes about 0.17 billion tons of CO2 per year. Assuming that seaweed is not needed as a food source and that it is farmed to cover an area 6 times greater than present and then mechanically harvested and sunk in the deep ocean where the pressure is such that it won’t float up, it might save 1 billion tons per year. However, before seaweed will absorb carbon, it must be fertilized with nitrogen and phosphorus. To provide these and to provide the energy to sink the seaweed to the depths, energy is required. That means, as on land, the energy should be provided by nuclear, wind and solar, and the use of seaweed should considered when there are land uses of fossil fuels and wood that cannot be be converted to the renewable sources.
Iron fertilization of the ocean to increase the amount of phytoplankton is another means of taking CO2 from the atmosphere. Phytoplankton already consume a large portion of the CO2 in the atmosphere. But their decomposition produces methane, and can produce dead zones for fish. And it is not known how much of the captured CO2 is released as the phytoplankton sink, nor how much each “bloom” reduces the nitrogen and phosphorus available for future blooms. Much additional research is necessary to evaluate the merit of this technology.
Two other ideas seem farfetched because they would in my opinion use more energy than they would save: 1) pumping cold water nutrient rich water from the deep ocean to the ocean surface (to enhance fishing, and algae growth) and 2) making sea water more alkaline, either by dumping humongous quantities of mined and ground alkaline rocks throughout the ocean, or by passing the ocean through an electro-chemical treatment.
- https://ieefa.org/resources/carbon-capture-crux-lessons-learned ↩︎
- https://www.newscientist.com/article/2336018-most-major-carbon-capture-and-storage-projects-havent-met-targets/ ↩︎
- https://sequestration.mit.edu/index.html ↩︎
- A somewhat lower estimate follows. The direct penalty is said to be 60% of the total penalty. https://www.sciencedirect.com/science/article/abs/pii/S2211467X14000716?via%3Dihub ↩︎
Is Geo-engineering – Blocking Solar Radiation – a possible solution?