A new direct air capture (DAC) method to remove carbon dioxide from the atmosphere has been proposed, and it's inspired by natural mechanisms.
Researchers in the UK have looked at how biological membranes transport chemicals passively through a flow between high and low concentrations, as Anthropocene reported. With this as a guide, they've built a special membrane by drilling conical holes into an alumina tube and filling the material with molten carbonate salt.
Then, they created a difference in humidity, with dry air as the input stream and wet air as the output. This triggered a spontaneous flow of carbon dioxide toward the output stream.
"The surprising thing about this membrane is how rapid the permeation process is," said Ian Metcalfe, a professor of chemical engineering at Newcastle University, per the report. "This seems to be due to the ability of water to release carbon dioxide from the strongly-bound carrier in the membrane."
Only about 0.04% of the air in the atmosphere is carbon dioxide, a planet-warming gas — though this amount has a big impact, as Reuters explains. Because of this, most DAC methods need to concentrate the carbon gas to speed up the chemical removal process, and that typically requires a lot of energy, as Anthropocene detailed.
The only energy needed for the humidity-driven process goes toward keeping the carbonate salts molten, which requires temperatures of over 400 degrees Celsius (752 degrees Fahrenheit).
"This means you would also need a large heat exchanger and some heat input to process the air," as Metcalfe shared in the report. "What we would like to do now is drop the temperature of operation, and we have ideas about how we could do this."
These DAC processes are needed to complement the Earth's own natural carbon cycle. The use of dirty fuels has tipped the natural balance in the atmosphere, which is warming the planet and causing sea levels to rise while also exacerbating extreme weather events.
This has led the U.S. government to fund new ventures aiming to reduce the concentrations of pollution in the atmosphere.
As of January, Statista reported that 15 carbon capture, utilization, and storage (CCUS) facilities are operating in the country, which collect carbon from industrial processes and either reuse or store it before it enters the atmosphere.
If the 121 additional projects that were in the works as of last September get completed, they could collectively remove 3% of our nation's current annual carbon pollution, per the Congressional Budget Office.
Concurrently, DAC options are also being explored, with $3.5 billion in funding supporting the Regional Direct Air Capture Hubs program. Four hubs will demonstrate different technologies at the commercial scale, with hopes of removing one million metric tons (about 1.1 million U.S. tons) of carbon annually.
Companies like GE are exploring their own solutions, while others are looking at using the natural heat from geothermal sources for energy to power this type of operation.
These projects can help our environment get back on track while improving air quality and introducing good-paying jobs in the clean energy sector. People can do their part to reduce pollution as well, by considering solar panels for their homes and opting for electric cars over gas-guzzling alternatives.
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