As many countries work to reduce their carbon dioxide (CO2) emissions, one potential solution that has been treated as a pie-in-the-sky concept has been making progress: a system that sucks CO2 directly from the air.

Called direct air capture (DAC), this method involves taking in air and running it through materials that absorb CO2. That material is then processed so the CO2 is removed and injected into a storage system, often underground. The process, however, is expensive.

Climeworks AG, a small Swiss firm, wants to change that perception of DAC, and the company is hoping that $30.8 million in new equity funding will help them do exactly that.

Taking CO2 out of thin air

Climeworks has two DAC pilot projects in operation. One is near Zurich, a plant that opened in June 2017 and should capture up to 900 tons (816 tonnes) of CO2 a year, or roughly the amount of CO2 emitted by 200 cars, according to E&E; News and reprinted by Science Magazine. The CO2 captured from this facility is sold to the agricultural firm Gebrüder Meier Primanatura AG to help grow greenhouse vegetables. The plant is expected to operate for at least three years.

The second project launched in Hellisheidi, Iceland, in late 2017. This plant combines the DAC process with carbon storage, setting up both at a geothermal power plant run by Reykjavik Energy. The DAC plant sucks up CO2 from the air around the plant and injects it more than 2,300 feet (700 meters) into the ground, a "permanent" carbon storage solution, according to Climeworks.

Climeworks hope its DAC technology will eventually be implemented widely enough to capture 1 percent of the man-made CO2 emitted a year by 2025.

Still, that seems a long way off, as Reuters, explains. The plants can take in around 1,102 tons of CO2 a year. To put that into perspective, global emissions of CO2 totaled 35.8 billion tons in 2017.

Additionally, the Climeworks' plants remove CO2 at the cost of about $600 a ton, making the process decidedly costly. The recently acquired equity funding will be used to help lower costs.

"It's all about cost reductions," Jan Wurzbacher, a co-founder and co-CEO of Climeworks, told Reuters.

This is especially important as one of Climeworks' DAC competitors, Canadian company Carbon Engineering, has outlined plans for a plant that can perform DAC for a minimum of $94 a ton, according to Reuters.

Too much cost for too little return?

A Climeworks DAC and carbon injection plant was set up at Iceland's Hellisheidi Power Plant, seen here. Arni Saeberg/Climeworks/The Helena Group Foundation/Wikimedia Commons

Some critics say DAC is least wasteful when it's set up around fossil fuel plants or factories.

In a story by E&E; News, Massachusetts Institute of Technology senior research engineer Howard Herzog referred to DAC operations set up away from coal energy plants as a "sideshow," citing concerns over the total system cost being around $1,000 a ton, or 10 times the amount that would be required at a coal plant.

"At that price, it is ridiculous to think about right now. We have so many other ways to do it that are so much cheaper," Herzog said.

Herzog didn't mention Climeworks by name in his discussion of DAC operations.

The criticism mainly rests on the fact that CO2's concentration is high around coal energy plants' exhaust flues, around 10 percent, according to Quartz. Capturing the CO2 at these locations requires significantly less energy, and is thus cheaper, because it's so prevalent; outside of power plants, CO2's presence can go to a concentration of only 0.04 percent in the air, making the energy and cost required to capture that CO2 significantly higher.

Still, there are plenty of sources of CO2 emissions that aren't power plants, as Quartz points out, and reducing the CO2 from those sources may help make a difference.

DAC operations are picking up steam in scientific and governmental reports. The authors of the "hothouse Earth" report from early August 2018 specifically mention removing CO2 emissions from the air as one of the ways we need to act to help the planet. Reuters reports that a United Nations report due in October 2018 is expected to boost "carbon dioxide removal" projects, like DAC, which is a shift in perspective that in the in the past has placed such projects in the same league as geoengineering.