To mitigate climate change, research teams and tech start-ups are developing direct air capture devices, which can collect carbon dioxide from the atmosphere directly. Although the technology works, the early projects have been costly and energy consuming.
Filters or liquid solutions are used in the systems to capture carbon dioxide from air pushed across them. Once the filters are full, the carbon dioxide must be released, and the capture cycle restarted using power and heat. The energy source must be carbon-free for the process to achieve net negative emissions.
The world's largest active direct air capture facility, located in Iceland, utilizes waste heat and renewable energy to pump the carbon dioxide into the underlying basalt rock, where it combines with the basalt and calcifies, and form solid material.
Recent research shows that offshore wind turbines could be used in a similar way.
If direct air capture systems are installed alongside offshore wind turbines, they would have an instantaneous source of clean energy from excess wind power and would be able to pump captured carbon dioxide directly to storage beneath the sea floor, decreasing the need for extensive pipeline systems.
Researchers are now investigating how these systems work in maritime environments. On land, direct air capture is just getting started, and the technology would almost certainly need to be tweaked for the harsh ocean environment.
Wind energy is intermittent. When the wind can generate more energy than is required, output is reduced and electricity that could otherwise be used is lost. Instead of wasting power, it may be utilized to collect carbon from the atmosphere and store it.
As offshore wind farms expand to fulfill this target, a surplus of 825 megawatt-hours of electrical energy could be predicted, based on historical wind curtailment rates in the United States. This surplus energy might be used to capture and store up to 0.5 million tons of carbon dioxide per year if direct air capture efficiency improves and meets commercial standards.
To keep global warming below 1.5 degrees Celsius compared to pre-industrial levels, the Intergovernmental Panel on Climate Change estimates that 100 to 1,000 gigatons of carbon dioxide will need to be removed from the atmosphere over the next century.
According to researchers, sub-seafloor geological formations near offshore wind projects proposed on the US East Coast have the capacity to store more than 500 gigatons of carbon dioxide. And basalt rocks are believed to exist in buried basins across this area, offering even more storage capacity and allowing carbon dioxide to react with the basalt and solidify over time.
New wind farms with direct air capture might offer renewable energy to the grid while also providing surplus electricity for carbon capture and storage, maximizing the direct climate benefit of this large investment.
