DAC stands for direct air capture, which is the process of capturing carbon dioxide (CO₂) directly from the atmosphere. The concentrated CO₂ gas is then compressed and liquified. The compressed CO₂ is either permanently sequestered in geologic storage deep underground (~6,800+ feet) or is converted to a usable product. The remaining air is exhausted back into the atmosphere. The DAC unit can be powered by waste heat and/or renewable energy sources.
Direct air capture (DAC) is crucial in addressing climate change because it helps remove excess CO₂ from the atmosphere, where human activities have significantly increased emissions beyond the Earth's natural capacity to sequester carbon.
Since the industrial revolution CO₂ concentrations have steadily increased in the atmosphere at exponential rates that are not attributable to natural geologic processes (e.g., a supervolcano eruption). Traditional industrial processes, electricity generation, and transpiration sectors have been a large contributing factor to this increase in atmospheric CO₂ (a greenhouse gas). Greenhouse gases warm the Earth’s atmosphere similar to how a garden greenhouse is warmer than the outside temperature.
The emission of CO₂ occurs naturally via respiration and wildfires and other environmental processes. The sequestration of CO₂ also occurs naturally in plants and the oceans. However, for hundreds of years human beings have steadily increased the amount of carbon dioxide we emit into the atmosphere and changed the natural landscape through industrialization and deforestation, reducing natural sequestration potential. Since the industrial revolution, there has been an imbalance of carbon dioxide: the rate of CO₂ emitted vastly exceeds the Earth’s natural CO₂ sequestering abilities.
It will take a suite of mitigating and adaptation actions to combat climate change. DAC is one of those key mitigation solutions to bring the Earth’s atmosphere back into balance.
A DAC hub is a regional scale interconnected network with the mission of reducing atmospheric CO₂ at commercial scale.
These are some examples of network partners:
The map on the right is the outline of the Illinois Basin, a geologic subsurface feature. The Illinois Basin is a massive oval depression that underlies roughly 70% of Illinois, extending about 60,000 square miles. Since the early 2000s, there has been strong interest in using the unique geology of the Illinois Basin to permanently store, or sequester, carbon dioxide (CO₂).