The release of the IPCC’s final section of its latest report in April 2022 contained a clear message: for the world event to have a chance of limiting future heating to 1.5°C above pre-industrial levels, we must actively remove CO2 from the atmosphere. Indeed, physical constraints and ethical considerations can make emissions reductions – however necessary they may be – extremely challenging. As a result, emissions from areas like electricity production, transport or buildings will need to be offset by removing an equal magnitude of carbon dioxide.
Every potential carbon dioxide removal solution includes benefits and trade-offs, and must be assessed through according to several criteria, including:
storage permanence (or durability)
natural resource usage
energy and material requirements
“Engineered” options such as direct air capture (DAC) are required to remove carbon at industrial scales, but are limited today because of their high energy requirement and associated costs. Because CO2 exists in minimal ambient concentrations (400 parts per million, or 0.04% by volume), capturing it is energy intensive. Current capture cost estimates range from $100 per ton to over $1,000 per ton. Reliable estimates expect costs to reach $200–300 in 2024 but remain at $50–150/ton, even in optimistic scenarios, by 2075. At scale, energy costs may be a significant hurdle to deploying DAC.