By 2030, the Biden administration’s goal is to have30 gigawatts of offshore wind energyflowing, enough to power more than 10 million homes.
Replacing fossil fuel-based energy with clean energy such as wind poweris essential to holding off the worsening effects of climate change. But that transitionisn’t happening fast enoughto stop global warming. Human activities have pumped so much carbon dioxide into the atmosphere that wewill also have to remove carbon dioxide from the airand lock it away permanently.
Offshore wind farms are uniquely positioned to do both—and save money.
As amarine geophysicist, I have been exploring the potential forpairing wind turbines with technology that captures carbon dioxidedirectly from the air and stores it in natural reservoirs under the ocean. Built together, these technologies couldreduce the energy costsof carbon capture and minimize the need for onshore pipelines, reducing impacts on the environment.
Capturing CO2 from the air
Several research groups and tech startups aretesting direct air capture devicesthat can pull carbon dioxide directly from the atmosphere.The technology works, but theearly projectsso far are expensive and energy intensive.
The systems usefilters or liquid solutions that capture CO2from air blown across them. Once the filters are full, electricity and heat are needed to release the carbon dioxide and restart the capture cycle.
For the process to achieve net negative emissions, the energy source must be carbon-free.
Theworld’s largest active direct air capture plantoperating today does this by using waste heat and renewable energy. The plant, in Iceland, then pumps its captured carbon dioxide into the underlying basalt rock, where the CO2 reacts with the basalt and calcifies,turning to solid mineral.
A similar process could be created with offshore wind turbines.
If direct air capture systems were built alongside offshore wind turbines, they would have an immediate source of clean energy from excess wind power and could pipe captured carbon dioxide directly to storage beneath the sea floor below, reducing the need for extensive pipeline systems.
Researchers are currently studying how these systems functionunder marine conditions. Direct air capture is only beginning to be deployed on land, and the technology likely would have to be modified for the harsh ocean environment. But planning should start now so wind power projects are positioned to take advantage of carbon storage sites and designed so the platforms, subsea infrastructure and cabled networks can be shared.
Read more:These machines scrub greenhouse gases from the air—an inventor of direct air capture technology shows how it works
Using excess wind power when it isn’t needed
By nature, wind energy is intermittent. Demand for energy also varies. When the wind can produce more power than is needed, production iscurtailedand electricity that could be used is lost.
That unused powercould instead be used toremove carbon from the air and lock it away.
For example,New York state’s goalis to have 9 gigawatts of offshore wind power by 2035. Those 9 gigawatts would be expected to deliver 27.5 terawatt-hours of electricity a year.
Based on historical wind curtailment rates in the U.S., a surplus of 825 megawatt-hours of electrical energy a year may be expected as offshore wind farms expand to meet this goal. Assuming direct air capture’s efficiency continues to improve and reaches commercial targets, this surplus energy could be used to capture and store upward of 0.5 million tons of CO2 a year.
That’s if the system only used surplus energy that would have gone to waste. If it used more wind power, its carbon capture and storage potential would increase.
The Intergovernmental Panel on Climate Change has projected that100 gigatons to 1,000 gigatonsof carbon dioxide will have to be removed from the atmosphere over the century to keep global warming under 1.5 degrees Celsius (2.7 Fahrenheit) compared with preindustrial levels.
Researchers have estimated thatsub-seafloor geological formationsadjacent to the offshore wind developments planned on the U.S. East Coast have the capacity to store more than500 gigatons of CO2. Basalt rocks arelikely to existin a string of buried basins across this area too, adding even more storage capacity and enabling CO2 to react with the basalt and solidify over time, though geotechnical surveys have not yet tested these deposits
Planning both at once saves time and cost
New wind farms built with direct air capture could deliver renewable power to the grid and provide surplus power for carbon capture and storage, optimizing this massive investment for a direct climate benefit.
But it will require planning that starts well in advance of construction. Launching the marine geophysical surveys, environmental monitoring requirements and approval processes for both wind power and storage together cansave time, avoid conflictsand improve environmental stewardship.
David Goldberg is a Lamont Research Professor and his interests focus on the integration of different technologies and cross-disciplinary approaches to develop achievable climate solutions.
This commentary was originally published by The Conversation—Offshore wind farms could help capture carbon from air and store itlong-term—using energy that would otherwise go towaste
