Direct Air Capture (DAC) offers a range of opportunities to produce products and create environmental benefits. At CE, we are focused on two main use cases: permanently storing the captured carbon dioxide (CO2) in underground geological reservoirs to create negative emissions, and utilizing captured atmospheric CO2 to produce clean synthetic transportation fuels.
Traditional use of fossil fuels extracts carbon from underground geological reservoirs. When used in our cars, homes, or power plants, the carbon is released into the air in the form of CO2, thus driving climate change. Direct Air Capture with secure geological storage can do exactly the reverse. By capturing atmospheric CO2 and permanently storing it underground, this form of ‘negative emissions’ or ‘carbon dioxide removal’ counteracts emissions that are occurring elsewhere.
Geological carbon dioxide storage, also known as carbon sequestration, has been assessed by leading international bodies such as the Intergovernmental Panel on Climate Change (IPCC). The IPCC and others have concluded that when storage sites are properly regulated, selected, and managed, CO2 can be stored permanently for millions of years with very low risk. Suitable locations for geological sequestration exist in many regions around the globe and collectively have the capacity to store hundreds of years of CO2 emissions underground.
Saline aquifers are large geological formations that are isolated deep underground and contain salt water. Extensive work by industry, academics, and government agencies has examined saline CO2 storage and determined that it presents a long-term mechanism for CO2 storage with immense capacity. Carbon storage in saline aquifers is being practiced in Norway and Algeria at commercial-scale, and pilot-scale projects have been demonstrated in Japan, Canada, Germany, and the US.
Permanently storing atmospheric CO2 in saline aquifers allows us to achieve what is known as ‘carbon dioxide removal’ or ‘negative emissions’. A DAC facility built in this way has the sole purpose of removing CO2 from the atmosphere. In the near-term, this will allow us to reduce the net amount of CO2 that is being released into the atmosphere. In long-term scenarios, when economies have made deep cuts to CO2 emissions, these same negative emissions facilities could be used to reduce the overall level of CO2 in the air back to levels deemed safe by climate scientists.
Injecting carbon dioxide into existing oil reservoirs is a common practice that has been performed by the oil and gas industry since the 1970’s, and is known as enhanced oil recovery (EOR). While historically EOR was not performed to achieve environmental benefits, the infrastructure and expertise in today’s EOR industry presents an attractive first use for DAC and CO2 that has been captured from the atmosphere. New laws and regulations – such as California’s Low Carbon Fuel Standard – are now giving guidance to experienced EOR operators on how to adapt their operations to ensure the CO2 is permanently stored underground during the process. If these criteria are met, atmospheric CO2 captured by DAC can be injected and left permanently stored in the process of producing oil.
In this case, the injection of atmospheric CO2 achieves a ‘negative emissions step’ while oil is produced. This flow of negative emissions, in which we permanently remove CO2 from the atmosphere and bury it underground, can partially or completely counteract the carbon emissions from the oil. Or, if the quantity of atmospheric CO2 permanently stored in the reservoir is greater than the quantity of oil (i.e. we put more in than comes out), this activity can produce oil and fuels for the transportation sector while also generating net negative emissions. For readers familiar with life-cycle analysis, this means that, depending on factors such as the pattern of the well and the operation of the oil reservoir, DAC with EOR can produce fuels with low, zero, or even negative life-cycle “carbon intensity”.
CE’s AIR TO FUELSTM technology combines our DAC process with several other advancing technologies to produce liquid hydrocarbon fuels. The process starts by using renewable electricity to split hydrogen from water, and then combines the hydrogen with captured atmospheric CO2 to produce synthetic crude. This ‘syncrude’ can then be processed into common gasoline, diesel, and jet fuel that works in the engines of existing cars, trucks, and airplanes without the need to modify them.
These fuels are cleaner burning than fossil fuels and can be produced with 100 times less land use than biofuels. Most importantly, our fuels can be produced and used with very low or even zero addition of CO2 to the atmosphere (depending on the energy source used to power the DAC facility). Burning our fuels releases the CO2 that was captured to produce them, but the process would add little or no new carbon emissions to the air because it creates a circular system of emissions in which we continually reuse the atmospheric CO2.