Cutting greenhouse gas emissions at the source should be the main goal when tackling climate change, but the most recent IPCC report also recommends carbon capture and storage technologies as key parts of the effort to limit global warming to 1.5°C.
The startup Heimdal is well aware of the need for such technologies, which is why it developed an innovative carbon removal machine that can store CO2 while helping reduce the ocean’s acidity.
Working with the ocean to capture CO2
Heimdal’s process involves pumping saltwater into the machine, which uses electricity to tweak molecular bonds in the water, removing acid. The resulting acid comes in the form of hydrochloric acid, which can then be used in many different industrial applications. The acid-free seawater is then pumped back into the ocean, where it will naturally capture CO2.
“When the excess acidity is removed from the ocean, it shifts how CO2 exists back to how it was pre-Industrial Revolution,” says Heimdal co-founder Erik Millar. “This moves it away from being carbonic acid, which causes ocean acidification, and toward bicarbonate and carbonate. These are stable forms of mineralized carbon dioxide that make their way down to the ocean floor, where they are stored for more than 100,000 years.”
Help reduce ocean acidification
The ocean currently absorbs about a third of the carbon dioxide humans release into the atmosphere. As the CO2 dissolves in the seawater, it contributes to ocean acidification, threatening the survival of corals and other calcifying marine life like shellfish. While the startup’s new process can help reduce ocean acidification on a local scale, its main focus is to capture high amounts of CO2 from the air.
Current direct air capture technologies typically use large fans to pull in and capture CO2 from the air. Heimdal’s machine looks at the ocean instead, where there’s a greater concentration of CO2 than in the air, enabling it to capture higher volumes of this planet-warming gas. Working together with the water also allows it to use less energy for the process, making it more affordable than conventional air direct air capture. Plus, it doesn’t need to be on land.
The technology has recently been put to use near the Big Island of Hawaii, where the machine is connected to a desalination plant. This helps the system save costs because the plant already does the heavy lifting of pumping the seawater from the ocean. The entire process runs on solar power.
“Carbon capture has only recently been able to take off because of this huge decrease in the cost of renewable green electricity in the past decade,” Millar says. “So, we’re running entirely on solar, and it’s cheaper than we could get from fossil fuel energy.”
The technology’s current version can capture CO2 at a cost of $475 per ton. That’s more affordable than any other direct air capture tech currently on the market. According to the team, the next plant — which will have a capacity of capturing 5,000 tons of CO2 per year — will operate at less than $200 per ton of CO2.