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Direct Air Capture (DAC) operating and energy costs are highly dependent on the energy sourced used, with current costing of fossil fuels tending to be cheaper than renewables, but having the negative effect of a higher net CO₂ output that can negate their effectiveness.

Summary​

Direct Air Capture (DAC) systems require massive operational and energy costs to meet climate goals of limiting atmospheric CO₂ to 450 ppm. Using IPCC RCP scenarios, operational costs range from $4.3-$140.9 trillion depending on sorbent type (liquid vs solid). Energy costs vary dramatically by source, with fossil fuels ($76.2-$310 trillion) being cheaper than renewables ($311.9-$1,541.8 trillion) but requiring more net CO₂ removal due to emissions. Current estimates show total costs far exceed global economic capacity, emphasizing the need for rapid decarbonization to reduce required CO₂ removal volumes to stabilize atmospheric CO₂ concentration.

Previously, we calculated that the capital costs required for Direct Air Capture (DAC) systems to meet the world's climate goals far exceed the global GDP in 2023. However, this costing does not include the operational and energy costs of the systems. As a general rule, liquid sorbents tend to have a lower capital cost, while solid sorbents tend to have a lower operational/energy cost. Operational costs are often presented independently from energy costs as the energy costs greatly depend on the energy source, be it renewable or non-renewable. It should also be noted that all DAC systems require electricity and heat to operate, so even when a 100% renewable grid is available, the energy from heat will most likely still be provided in the short term by a non-renewable source as it the most effective way to produce heat.

Capital costs to meet climate goals​

Knowing the capital costs, it is possible to roughly estimate the combined operational and energy costs of DAC systems in their current state of pricing to meet an arbitrarily chosen climate goal of "limiting the atmospheric concentration of CO₂ to 450 ppm by 2100" using the International Panel on Climate Change (IPCC) Representative Concentration Pathways (RCPs). From these previous calculations, we estimated the amount of carbon dioxide (CO₂) that would need to be removed from the atmosphere for the three main RCPs is shown in table 1.

Table 1: Atmospheric CO₂ removal required to achieve 450 ppm or less for each RCP scenario

ScenarioProjected 2100 CO₂ concentrations (ppm)Estimated average global temperature Rise Range (°C)CO₂ Removal required (Gt)
RCP 2.64000.9 – 2.41300
RCP 4.55251.7 – 3.3866.4
RCP 8.59003.2 – 5.73522.6

Operational costs​

Estimates for operational costs (such as maintenance and labor) for liquid sorbents are between $40-$80/tCO₂ while for solid sorbents they are between $5-$50/tCO₂ 1. Using the assumption that the operational costs are equal to the lower bound $40/tCO₂ for liquid sorbents and $5/tCO₂ for solid sorbents, we can estimate the operational cost for each RCP by multiplying the amount of CO₂ removed by the operational cost per tonne of CO₂

 Operational cost≈Amount of CO2 removed [Gt]×109×Capital cost per tonne of CO2 [$/tCO₂]\begin{align*} \text{ Operational cost} &\approx \text{Amount of CO}_2 \space \text{removed [Gt]} \times 10^9 \times \text{Capital cost per tonne of CO}_2 \text{ [\$/tCO₂]} \\ \end{align*}

Table 2: Estimated operational costs (excluding energy costs) for DAC deployment by scenario and sorbent type

ScenarioSorbent TypeOperational Cost (USD trillion)
RCP 2.6Liquid Sorbents$52
Solid Sorbents$6.5
RCP 4.5Liquid Sorbents$34.7
Solid Sorbents$4.3
RCP 8.5Liquid Sorbents$140.9
Solid Sorbents$17.6

Energy costs​

Estimating the energy costs of a DAC system is not a straightforward task as it depends heavily on the energy source used. Additionally, energy sources that pollute the atmosphere with more CO₂ effectively negate some of the CO₂ removed by the DAC system, so more net CO₂ would need to be removed to be compared to a cleaner energy source. Generally, the requirement for thermal energy is greater than the requirement for electrical energy as the sorbent regeneration phase requires a large energy input to release the captured carbon dioxide 2. Although possible, converting electrical energy into thermal energy is not common, as the energy conversions of that nature is economically inefficient, requiring greater input compared to thermal sources. Shown below in table 1 are the estimated energy costs for each energy source independent of sorbent technology used 1. Note, these energy values are for a full system estimate including real-world losses and inefficiencies, and are different from the minimum energy requirement that was previously calculated. It should also be noted that the costs for renewable sources will continue to decrease as the technology matures and the scale of deployment increases.

Table 3: Estimated energy costs by energy source

Energy SourceEnergy Cost ($/tCO₂)
Solar$430 – $690
Wind$360 – $570
Coal$88 – $228
Natural Gas$88 – $228
Nuclear$370 – $620

As can be seen, the energy cost with fossil fuels is significantly lower due to their ability to provide low-cost and high-intensity thermal energy. However, the values presented do not account for the additional CO₂ produced through the burning of fossil fuels which would require more CO₂ to be removed in order to achieve the same net CO₂ removed as the renewable and nuclear energy sources 1 2. It is estimated that utilizing coal as the sole energy source would produce close to half as much CO₂ as had been removed, bringing the energy cost between fossil and renewables closer to parity 1.

Using the low bound of the energy cost for each of the energy sources listed above, we can calculate the energy cost for each RCP as shown in table 4. The enormous energy cost values highlight the urgent need for rapid decarbonization to reduce the amount of CO₂ needed to be removed from the atmosphere.

Table 4: Energy costs by scenario and energy source (USD trillion)

Energy SourceRCP 2.6RCP 4.5RCP 8.5
Solar$559$372.6$1,541.8
Wind$468$311.9$1,286.2
Coal$114.4$76.2$310
Natural Gas$114.4$76.2$310
Nuclear$481$320.6$1,303.4

Sources​

Footnotes​

  1. Ozkan, M., Nayak, S. P., Ruiz, A. D., & Jiang, W. (2022). Current status and pillars of direct air capture technologies. iScience, 25(4), Article 103990. https://doi.org/10.1016/j.isci.2022.103990 ↩ ↩2 ↩3 ↩4

  2. National Academies of Sciences, Engineering, and Medicine. (2019). Negative emissions technologies and reliable sequestration: A research agenda. Washington, DC: The National Academies Press. https://doi.org/10.17226/25259 ↩ ↩2