This article explains how to simulate the deployment of direct air carbon capture and storage (DACCS) technology in En-ROADS as well as the impact of DACCS on CO₂ emissions and the climate. Watch the video below for a summary.


 

What is direct air carbon capture and storage (DACCS)?

Direct air carbon capture and storage (DACCS) is a technological carbon dioxide removal (CDR) method for pulling CO2 out of the atmosphere. The system involves capturing CO2 from the air, transporting it to a storage site, and sequestering the CO2 in underground geological formations (see the image below and refer to the CDR infographic for all methods available in the simulator).

En-ROADS includes sliders and graphs to simulate the growth of DACCS. It also models other carbon capture and storage (CCS) methods, including coal CCS, natural gas CCS, and bioenergy CCS (BECCS). While DACCS pulls CO2 directly from the air, other forms of CCS (i.e., coal, natural gas, BECCS) capture emissions at their source before they enter the air. DACCS and CCS methods are still emerging technologies that face transportation and long-term storage constraints, but DACCS costs are significantly higher due to the large amount of energy needed to power the equipment. To learn more about CCS and BECCS, read the CCS in En-ROADS Explainer and the Bioenergy in En-ROADS Explainer. Also, refer to the glossary for definitions of these similar but distinct terms.

What is the current status of DACCS?

The best graph to see the scale of deployment of DACCS in En-ROADS is the “Sources of Anthropogenic CO2 Removals” (under Graphs > CO2 Removals). In the Baseline Scenario DACCS remains at nearly zero, reflecting that to date, only 5 DAC plants are operational worldwide, capturing just 1,000 tons of CO2/year (EFI Foundation, 2024)—or 0.000001 Gt of CO2 per year. This is an extremely small amount compared to global CO2 net emissions, which are over 43 Gt per year in 2025 as shown in the “CO2 Net Emissions” graph.

The DACCS technology is extremely expensive due to how new the technology is and how much energy is required to power it, as the “Cost of Direct Air Carbon Capture and Storage” graph (below and under Graphs > Financial) shows. The default initial cost of $650/ton CO2 can be changed in the Assumptions—under Simulation > Assumptions > Carbon capture and removals > Direct air carbon capture and storage (DACCS)—to reflect an uncertainty range from $300-1000 per ton of CO2 stored.

How to simulate the DACCS deployment in En-ROADS?

To simulate DACCS deployment in En-ROADS, subsidize it directly or add a carbon price that encourages investment in DACCS.

1. Subsidize DACCS under Technological Carbon Dioxide Removal

Users can adjust the main “Technological” slider under the “Carbon Dioxide Removal” section to simulate the deployment of all technological CO2 removal methods, i.e., DACCS and enhanced mineralization. Alternatively, users can access the advanced view of the slider to subsidize DACCS only.

For example, consider a subsidy of $650/ton CO2 captured, like in this scenario. To put this in perspective, the U.S. tax credit under Section 45Q of the U.S. Internal Revenue Code—an ambitious government policy—provides $180/ton CO2 captured.

The effect of this high subsidy makes DACCS grow at an average rate of ~50% per year during 2035-2040, and ~12% from 2041-2050, resulting in 0.35 Gt CO2 captured per year by 2050 and 0.85 Gt by 2100. 

2. Add a carbon price that encourages DACCS in addition to the subsidy 

A carbon price typically increases the cost of energy sources according to how much CO2 they emit. Since DACCS would remove CO2 from the air, it could generate carbon credits that emitters can sell or trade to lower their costs. However, because DACCS deployment remains uncertain, carbon pricing mechanisms may or may not classify DACCS as eligible for credits or tax reductions. Users can control this incentive using the “Carbon price encourages direct air carbon capture and storage (DACCS)” switch in the advanced view of the Carbon Price slider.

Due to the high cost of DACCS, a carbon price alone may not significantly drive its adoption, but it can boost its growth when subsidies are in place. For example, in this scenario, combining $100/ton CO2 carbon price with a DACCS subsidy of $650/ton CO2, enables DACCS to remove 1 Gt CO2 per year by 2075.

Why does DACCS not grow more?

DACCS does not grow further because it is very expensive and it is unlikely to benefit significantly from economies of scale.

The “Cost of Direct Air Carbon Capture and Storage” graph below (under Graphs > Financial) reflects this high cost, which is expected to decrease over time with learning, if a high DACCS subsidy is implemented, like in this scenario (see the blue line below the black line). However, the default progress ratio for DACCS—adjustable under Simulation > Assumptions > Carbon capture and removals > Direct air carbon capture and storage (DACCS)—is 0.9, which means that every doubling of capacity reduces costs by only 10%.

The “Total Annual Cost to Capture and Store Carbon” graph provides another perspective of the significant annual costs that governments or businesses would need to cover to deploy DACCS and other CCS technologies.

What is the impact of DACCS on emissions and the climate?

To assess the impact of DACCS on emissions and temperature, consider a scenario where DACCS receives the maximum available subsidy of $1,000/ton CO2. Even with this high subsidy, the temperature reduction by 2100 remains minimal, compared to the Baseline Scenario, as shown in the “Temperature Change” graph (see the blue line slightly below the black line in the graph to the right). This policy drives DACCS deployment to about 1 Gt CO2 per year by 2080, as shown in the “Sources of Anthropogenic CO2 Removals” graph (left).

The temperature impact remains negligible because the CO2 removed by DACCS is overshadowed by the enormous amount of ongoing CO₂ emissions in absence of other types of action. The “Greenhouse Gas Net Emissions by Gas” graph below shows that in the Baseline Scenario, total gross greenhouse gas emissions rise to about 70 Gt CO2 equivalent per year by 2100 (represented by all wedges above the zero line), while DACCS sequesters only 1 Gt of CO2 per year (a small grey wedge below the zero line).

Other important factors in the system

Energy Use

CO₂ makes up only 0.04% of the atmosphere, so capturing a ton of it requires filtering huge volumes of air, making the DACCS process highly energy-intensive. The “Energy Used to Capture and Store Carbon” graph (left, under Graphs > CO2 Removals) shows the energy required for DACCS, along with other CDR and CCS methods. While CCS also requires energy, it captures CO2 from flue gas in coal, natural gas, and bioenergy facilities, where CO2 concentrations are much higher (5-20%). This means that DACCS must filter far more air than CCS to capture the same amount of CO2. For example, in a scenario with a $650 subsidy, DACCS scales to a level that requires about 2 exajoules of energy by 2050 to operate (light blue line).

Transport and pipeline capacity

The “CO2 Transport Capacity” graph represents the volume of infrastructure needed to transport sequestered CO2 to permanent storage. This includes pipelines, pumps, injection sites, and other transport methods required for DACCS, as well as for fossil CCS and BECCS.

Storage and leakage

The graph “Sources of Anthropogenic CO2 Removals” includes any losses that occur when storage is not permanent. There are uncertainties about how much leakage could happen from the geological storage sites. By default, En-ROADS assumes the leak rate is zero, but users can change this assumption under Simulation > Assumptions > Carbon dioxide storage > CO2 storage leak rate.