Direct air capture machines

Huge potential to mitigate climate change

DAC technology has been mooted for years, but faced huge engineering challenges and, until recently, was dismissed as a costly fantasy.

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.

Now the first plants are coming online, with the Intergovernmental Panel on Climate Change (IPCC) recognising 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.

The DAC plant in Iceland is the first in the world to be operated commercially.(Supplied: Climeworks)

In short, the IPCC says, the world needs to both reduce future emissions and remove historical ones to reach a safe climate.

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 just plant more trees?

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. When scaled up, it’s called a forest.

“My first thought was why not plant more trees,” Professor D’Alessandro said.

“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. “Not only do we not have the land, we don’t have the water to achieve natural sequestration.”

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 not only need to reduce greenhouse gas emissions, we also have to absorb CO2 from 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 just one of several proposed technologies designed to remove emissions from the atmosphere, which also include repurposing offshore oil and gas platforms to grow seaweed, and turn it into fire-resilient bricks.

DAC works a little bit like a household dehumidifier, but instead of stripping water out of the air, it removes carbon dioxide.

DAC would have to be scaled up enormously to be useful.(Supplied: Carbon Engineering)

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.

“To be frank, it’s been one of the most interesting scientific problems in chemistry in the past 10 years,” Professor D’Alessandro said.

There are generally two 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 with the CO2 molecules, removing them from the air and trapping them in the liquid solution as a carbonate salt.

The second method uses a sponge-like filter that absorbs CO2 and is then reheated to release the gas into storage.

In the case of the plant in Iceland, the captured CO2 is injected about a kilometre underground into volcanic rock.

Over two years it reacts with the basalt to form a solid carbonate material.

The captured carbon dioxide is injected into the ground at these nearby pods.(Getty Images: Arnaldur Halldorsson)

But underground storage isn’t the only option, Professor Howden said.

“Probably the dumbest thing we can do with captured CO2 is put it in the ground,” he said.

“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.

Is this any different to carbon capture and storage?

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.

Read more

Instead of filtering the air, it filters emissions from a smokestack.

Though the Australian government has singled CCS out as a priority technology for emissions reduction, critics have said it’s a failure.

One of the major problems is CO2 leaking from underground reservoirs.

With DAC, there’s a much lower risk of leakage, Professor Howden said.

“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 needs to be captured?

DAC would need to be enormously scaled up to be useful.

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 DAC plant in Iceland, which is the world’s biggest, can capture and remove 4,000 metric tonnes of CO2 a 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.

The “mechanical tree” concept uses wind, rather than fans, meaning a much lower energy cost.(Supplied: Silicon Kingdom Holdings)

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.

“To be an effective solution for climate change, an entire carbon removal industry will need to develop over a period of the next 10 to 20 years, creating capacities of at least 5 billion tonnes of carbon removal by 2050,” he said.

Professor Howden estimated DAC would ultimately account for a more modest amount of carbon removal.

“DAC of 1 to 1.5 billion tonnes of CO2 a year is potentially feasible,” he said.

What does it cost?

DAC is currently prohibitively expensive, mainly due to the cost of energy.

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.

That’s still a lot more expensive than offsetting CO2 by planting trees, which costs as little as $US20 ($28) per tonne.

Bushfires can release carbon sequestered in timber and undo millions of tonnes of offsets.(Supplied: Jochen Spencer)

So who’s paying Climeworks a premium for DAC offsets?

“We have an array of corporate clients such as Stripe, Audi, Shopify, Microsoft, Swiss Re, Boston Consulting Group,” Mr Egger said.

Microsoft, for instance, has committed to going carbon negative by 2030 and is investing $US1 billion ($1.4 billion) from 2020 to 2024 to “stimulate and accelerate the development of carbon removal technology.”

Is Australia doing DAC?

There are several proposed DAC projects in Australia, but nothing yet at a commercial scale.

Energy giant Santos struck a deal with CSIRO last November to trial the government agency’s new DAC technology 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.

An illustration of the solar-powered DAC module technology developed at University of Sydney.(Supplied: Southern Green Gas)

These could be deployed in non-arable parts of Australia with high levels of solar radiation, said Professor D’Alessandro, a member of the team.

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.

Australia’s abundant solar energy makes it an ideal location for DAC, Professor Howden said.

“DAC takes a lot of energy, so increasingly that will be sourced from renewables.

“And increasingly renewables are getting cheaper and cheaper and at some times of the day the costs are negative.”

But for the industry to prosper, it will need a price on carbon and more research funding for universities, he said.

It will also need public support, as the solar panels and wind capture systems used for DAC will take up land.

“Would the public like those sorts of things dotted across the landscape?” Professor Howden said.

“We need 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.”

Offsetting your emissions: Greenwashing or a win for the environment?

ABC Science


By Bernie Hobbs and environment reporter Nick Kilvert

Posted Tue 1 Sep 2020 at 2:22pmTuesday 1 Sep 2020 at 2:22pm, updated Tue 1 Sep 2020 at 2:26pmTuesday 1 Sep 2020 at 2:26pm

There are a range of offset projects designed to remove carbon from the atmosphere.(Getty Images: Cavan)

Help keep family & friends informed by sharing this article


Can you really pay someone to remove enough CO2 from the atmosphere to counter what your actions are putting into it?

Key points:

  • Offsets are designed to neutralise carbon dioxide emissions and are certified by third parties
  • They can buy us time to transition to clean energy but cannot reverse the burning of fossil fuels
  • Just 1 per cent of Australians offset their flights

When it comes to slashing greenhouse emissions from flying, nothing beats a global pandemic. But when air travel ramps up again, will you be ticking the “offset flights” box?

Does offsetting actually achieve anything much at all?

The answer is a qualified yes.

The carbon offset programs offered by Qantas, Jetstar and Virgin are all certified by the government-backed Climate Active program.

According to a spokesperson from Climate Active, that means they pass some essential criteria.

“Qantas and Virgin have undertaken a comprehensive life cycle assessment (LCA) of energy usage in flight and on the ground,” the spokesperson said.

“The airlines apply a functional unit to passengers and their travel to give a total footprint which is offset with eligible offsets.”

What that means in practice is that if you pay the $0.95 offset fee for an economy seat on a flight from Sydney to Melbourne, then 71kg of carbon dioxide (your share of the emissions from the flight) are removed from the atmosphere somewhere else.

So what does that “somewhere else” look like?

Offsetting stacks up

There are nearly 800 carbon offset projects across Australia.

One of them is the Yarra Yarra Biodiversity Corridor, where more than 29 million native trees have been planted in south-western Western Australia.

By reforesting thousands of hectares of habitat for threatened species, nearly 2 million tonnes of CO2 will be removed from the atmosphere and protected for 100 years, according to project leaders Carbon Neutral.

A draft report into that project has found the co-benefits — employment, ecosystem services — are worth more than the carbon sequestration, according to CEO Ray Wilson.

“Last study we found 54 bird species, and we’re looking at employing more Indigenous people,” Mr Wilson said.

Given the increasingly steep rate needed to reduce our carbon dioxide emissions in order to keep warming below 1.5 and even 2 degrees Celsius, Mr Wilson believes offsetting is necessary.

“A lot of us are making efforts to reduce our footprint as households and some governments. But if we go totally renewable for our power there will still be a mass of carbon dioxide in the atmosphere,” he said.

“I just don’t think we can reach our [emissions reduction] targets without offsetting.”

Other projects include fire management in Arnhem Land, ecosystem regeneration in New South Wales, as well as working with farmers to improve beef herd management and reduce methane emissions, soil-carbon sequestration, and developing solar and wind farms and battery storage.

The Yarra Yarra Biodiversity project is restoring habitat as well as capturing nearly 2 million tonnes of carbon.(Supplied: Carbon Neutral)

This carbon accounting and offsetting is also independently audited and certified through a third party validation, according to Climate Active.

The Yarra Yarra Biodiversity Corridor project for instance, is a certified Gold Standard project. Gold Standard is a certification body established by WWF and other NGO partners to ensure carbon reduction schemes feature the “highest levels of environmental integrity”.

So the certification program and its independent third party auditing means that in carbon-accounting terms, offsetting stacks up.

But too few of us are doing it

Only 1 per cent of Australians opt to offset their flights.

And that extremely low rate means we barely make a dint in our aviation emissions.

So can offsetting be the answer to getting our future (post-COVID) aviation emissions down? Most major airlines think it is.

Under the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), international airlines are committing to capping emissions at 2020 levels and reaching net zero emissions by 2050.

And their key mechanism to achieve that is by offsetting emissions.

According to a Qantas spokesperson, Qantas is “meeting our commitments of capping emissions at 2020 levels and reaching net zero emissions by 2050”.

“… And Qantas is matching dollar-for-dollar every contribution a customer makes to offset their emissions on a passenger flight, effectively doubling the program.”

So offsetting is the answer?

Biological carbon cycles from the earth to the atmosphere and back again over relatively short time periods. For instance, carbon dioxide is sucked from the atmosphere by a tree and it stays locked in that tree as carbon for the duration of the tree’s life. When that tree dies of old age and rots or is burnt, that carbon is then released back into the atmosphere as carbon dioxide.

That cycle can take as little as a few years to a few hundred years. But the carbon locked away in fossil fuels has taken millions of years to be sequestered. When we dig it up and burn it, we’re taking that geological carbon and putting it into the biological carbon cycle.

Permanently removing all that geological CO2 that we’re releasing into the atmosphere will also take millions of years because it requires slow-moving geological processes. Alan Pears, a senior industry fellow at RMIT, spends much of his time calculating emissions and admits he’s “a bit obsessed”. He gifts family and friends offsets at Christmas time, and said that while the main game needs to be avoiding emissions in the first place, offsets can be valuable during this energy transition period. “People say you shouldn’t use them because it’s just buying your way out of the guilt,” Mr Pears said. “[But] the other side of it is very few people are in a position to live a carbon neutral lifestyle.” Resources such as the UN’s Climate Neutral Now are available to help businesses and individuals find offset programs in their region or which they may have a particular interest .

Are you cynical about carbon offsetting? These experts say you shouldn’t be

There are nearly 800 carbon offset projects across Australia. But do they really stack up? Read more

Does carbon capture and storage really work?

Part of Australia’s net zero by 2050 plan is to use carbon capture and storage to help get emissions down. But is it a realistic option? Read More

Courtesy of ABC Science and James Purtill