Many efforts to reduce the effects of climate change are focused on reducing carbon dioxide emissions from the various sectors that contribute to them, for example electricity/heat production, agriculture, transportation, and industrial uses. In most of these sectors, there are "low-hanging fruit": certain emissions that can be removed with existing technology, sometimes even saving money in the process. For example, solar and wind energy are now often cheaper than coal, and electric cars can be cost-competitive with gasoline cars in some contexts. On the other hand, there are many processes which generate CO2 that do not currently viable zero-emissions replacements, such as steel/concrete production or passenger airlines.
One way to make progress on CO2 reductions in spite of this would be to directly capture CO2 from the air and store it, so that on balance, no additional CO2 is added to the atmosphere. Unfortunately, current projects from companies such as Carbon Engineering or Climeworks are typically at very small scales and quite expensive, on the order of $600 per metric ton.
When will direct air capture technology cost less than $50 per metric ton of carbon dioxide removed from the atmosphere?
- This cost is a few times higher than the current price of carbon offsets, such as from TerraPass, which may be implemented by e.g. capturing methane (a greenhouse gas) from landfills or farms.
- The cost per ton must be calculated from the actual carbon removed and costs incurred from some actual direct air capture project, not a hypothetical estimate.
- The project or company in question must have removed 1 million metric tons of CO2, equivalent to ~1% of the current voluntary carbon market.
- The cost must include all lifecycle costs amortized per ton of CO2, including building the plant. For example, if a plant cost $1 billion and has removed 1 ton of carbon so far, the cost is $1 billion per ton.
- Any offsetting revenues, such as from sale of the CO2 or derivative products, are not counted.
- Cost is in 2020 US dollars, adjusted for inflation.
- Resolution is by credible media report that this has occurred. Multiple reports can be combined; for example, sources on the construction cost of a plant, running costs, and total carbon removed so far can be used to compute an implied cost per ton.
ETA (2020-06-19) Planting trees does count as a carbon dioxide removal method for the purpose of this question.