On a barren lava plateau in Iceland stands an entirely new kind of industrial facility that sucks carbon dioxide from the air and traps it in stone.
The world’s first commercial direct air capture (DAC) plant is designed to remove thousands of tonnes of greenhouse gas every year and then inject it deep underground.
Technology like this has been mooted for years but faced huge engineering challenges and, until recently, was dismissed as a costly fantasy.
The first plants are now available online. The Intergovernmental Panel on Climate Change, (IPCC), recognizes that, even if the world reduces its ongoing emissions as quickly as possible, there will still be too much CO2 in the atmosphere to avoid catastrophic levels of global warming.
In short, the IPCC says, the world needs to both reduce future emissions AndTo create a safe environment, you can remove old ones.
Experts say DAC could become a trillion-dollar global industry — if it can be deployed at scale.
So how does DAC work, what’s the future of the carbon removal industry, and is this an opportunity for renewables-rich Australia?
Why not plant more trees instead?
When Deanna D’Alessandro, a professor of chemistry at the University of Sydney, encountered the idea of mechanical carbon removal, she wondered if there wasn’t a simpler solution.
A tree, of course, is a pre-existing and relatively cheap technology that sequesters CO2 in wood and other biomass.
It is called a “forest” when it is enlarged.
Professor D’Alessandro stated, “My first thought was why don’t we plant more trees.”
“And then I did the numbers and stood in awe of them.”
By her own calculations, using reforesting to capture Australia’s CO2 emissions for two years, (about 1 billion tonnes), would require an area of land equivalent to the size of New South Wales.
DAC could do the same with 99.7 per cent less space, she said.
Mark Howden, director of the Climate Change Institute at the Australian National University, agrees.
“The science is very clear that to keep temperatures down to [an increase of]1.5C. We need to not only reduce greenhouse gas emission but also absorb CO2 out of the atmosphere,” he said.
“It’s increasingly clear that doing that just from planting trees and relying on farmers and soil carbon is not enough.”
How does direct air capture work
DAC is one of many. proposed technologies designed to remove emissions from the atmosphere, which also include repurposing offshore oil and gas platforms to grow seaweedTurn it into fire-resilient bricks.
So, DAC works a little bit like a household dehumidifier, but instead of stripping water out of the air, it removes carbon dioxide.
The greatest challenge, says Professor D’Alessandro, is processing enough air to capture a significant amount of CO2, given the gas makes up just 0.04 per cent of the air we breathe.
There are two main approaches.
In the first, a fan pulls air into a structure lined with thin plastic surfaces that have potassium hydroxide solution flowing over them.
The solution chemically binds to the CO2 molecules. This removes them from the air and traps them in the solution as a carbonate sodium.
Meanwhile, in the second method, a sponge-like filter absorbs CO2, which is then reheated to release the gas into storage.
The captured CO2 is injected into volcanic rock about a kilometre underground in the case of the Iceland plant.
It reacts with the basalt for two years to form solid carbonate.
But underground storage isn’t the only option, Professor Howden said.
“Probably the dumbest thing that we can do with captured carbon dioxide is to put it into the ground,” he stated.
“To my mind, if we’ve gone to the bother of capturing CO2 why not treat it as a resource?”
Another DAC company, Canada’s Carbon Engineering, plans to use captured CO2 as an input to make carbon-neutral synthetic fuels that can substitute for diesel, petrol, or jet fuel.
Other proposals include using CO2 in cement production and plastics manufacturing, which could make buildings and water bottles carbon negative.
Are these any different to carbon storage and capture?
CCS involves capturing CO2 at the site of production, such as a gas liquefaction plant or coal-fired power station, and then pumping it deep underground.
Instead of filtering the air, it filters emissions from a smokestack.
Although the Australian government has singled CCS out as a priority technology for emissions reduction, Critics have called it a failure.
One of the main problems is the CO2 leakage from underground reservoirs.
Professor Howden stated that DAC has a lower risk of leakage.
“With standard CCS you’re restricted in the geology to somewhere close to the point of combustion, whereas you can put a DAC system anywhere, so you find geology that’s suitable and locate it there.”
How much CO2 must be captured?
DAC would be required to beExceptionally Scaled up to be of use
Even if the world reaches net zero by 2050, it will still be necessary to remove 5 to 14 billion tonnes of CO2 per year from the atmosphere from 2030 onwards to keep global warming below the 1.5C limit set by the Paris Agreement, according to a University of Melbourne report.
The largest DAC plant, located in Iceland, can capture and extract 4,000 metric tonnes CO2 each year.
That’s about 10 million times less than annual global emissions.
At our current level of emissions, humanity is cancelling out the plant’s yearly efforts every three seconds.
Daniel Egger, the chief commercial officer of Climeworks, the operator of the Iceland facility, said the company was on track for “megaton capacity” by the second half of this decade.
He said, “To be an effective solution to climate change an entire carbon removal sector will have to develop over the next ten to twenty years, creating capacities at least 5 million tonnes of carbon removal by 2020.”
Professor Howden estimated DAC would ultimately account for a more modest amount of carbon removal.
He stated that a DAC of 1 to 1.5 billion tonnes CO2 per year is possible.
What does it cost to do this?
DAC is currently prohibitively costly due to high energy costs.
Climeworks has priced its DAC offsets at about $US775 ($1,094) a tonne and says this will fall as low as $US250 ($353) by the end of the decade.
The US Department of Energy recently announced a goal of slashing the cost to $US100 per tonne ($141) by the end of the decade.
This is still a lot more costly than offset CO2 by planting trees. It costs only $US20 ($28) per ton.
Climeworks gets a premium price for DAC offsets.
Mr Egger stated that “we have a variety of corporate clients like Stripe, Audi Shopify, Microsoft and Swiss Re,”
Microsoft, for example, has committed to becoming carbon neutral by 2030. It is investing $US1B ($1.4 Billion) between 2020 and 2024 to “stimulate, accelerate the development and deployment of carbon removal technology.”
Is Australia doing DAC?
There are several DAC projects that Australia has been considering, but none of them have been completed on a commercial scale.
Santos Energy, a major in the energy sector, reached a deal with CSIRO last December to test the new DAC technology of the government agency in South Australia.
That same month, Elon Musk’s philanthropic research foundation awarded a University of Sydney team $250,000 to develop solar-powered DAC modules the size and shape of a two-person tent.
Professor D’Alessandro of the team said that they could be deployed in areas where solar radiation is high.
A start-up named Southern Green Gas (SGG) plans to produce and deploy at least some of these modules by the end of the year.
Professor Howden said that Australia’s abundant solar power makes it an ideal location to host DAC.
“DAC takes a lot of energy, so increasingly that will be sourced from renewables.
But, according to Professor Howden, for the industry to prosper, it will need a price on carbon and more research funding for universities.
It will also require public support as the solar-capture and wind-capture systems that are used to power DAC will occupy land.
“Would the public enjoy these types of things dotted across landscapes?” Professor Howden said.
“We have to put in place [systems of support for DAC] early and that requires proactivity, which requires vision and foresight.
“If we’re smart about this, this could be a billion-dollar earner for Australia.”