Bricks made from CO2 captured from the air hold promise in climate change fight

As World Environment Day is marked, many companies are working on ways to remove carbon dioxide from the air

Michael Evans, chief executive of Cambridge Carbon Capture, shows a brick made with CO2 from the atmosphere.
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Standing in his company's laboratory, Michael Evans holds up a small white brick that could be part of the solution to climate change.

Although hard to the touch, the block is made of crystals and is remarkably light, weighing about the same as a sponge.

What makes it so notable is that it has been produced using carbon dioxide (CO2), a greenhouse gas, taken from the air.

“We are mineralising it,” said Mr Evans, who is the chief executive of Cambridge Carbon Capture. “We're not only capturing it at low concentrations, but taking it and making it into solid rock.”

Mr Evans was speaking in the lead up to World Environment Day, which is marked annually on June 5. His technology marks another endeavour to rid the atmosphere of harmful chemicals.

Harmful greenhouse gases

In pre-industrial times, there were about 280 parts per million (ppm) of CO2 in the atmosphere, but now the concentration of this gas is about 421 ppm.

With CO2 emissions from energy and industry reaching a record high of 36.8 billion tonnes last year, the concentration is rising ever faster.

Without actually removing CO2 we’re not going to be able to survive this. It’s absolutely essential to the future of mankind or any other kind of life on Earth
Michael Evans, CEO of Cambridge Carbon Capture

Without significant measures to cut emissions, the concentration of CO2 gas could reach 550 ppm by 2060.

That would cause the average temperatures to rise to 2.6°C or more above pre-industrial levels, which could have devastating consequences.

One solution is to take CO2 out of the atmosphere and store it, known as direct air capture (DAC).

“Without actually removing CO2 we’re not going to be able to survive this,” said Mr Evans. “It’s absolutely essential to the future of mankind or any other kind of life on Earth.

“We need to pull out all the stops and every possible idea needs to be explored with maximum investment.”

DAC could remove up to 310 gigatonnes, or billion tonnes, of CO2 from the atmosphere by 2100, experts have suggested, as long as there is rapid scale-up.

Finding solutions

Cambridge Carbon Capture was founded in 2011 and is based in a small industrial park on the edge of Cambridge in the UK.

It is one of several companies developing DAC technology.

Last year, the company was awarded a £3 million (Dh13.6 million) contract by the British government to develop its methods.

“We believe the technology can make profit from capturing and sequestering CO2 for ever,” Mr Evans said. “Our technology is a process that takes low-value minerals and creates high-value products, in the process capturing CO2.”

The starting products include powdered magnesium silicates, a commonly found mineral containing useful metals such as nickel and cobalt.

This is processed with a specialist catalyst, converting it to silica and magnesium oxide, liberating the metals and making them easy to extract.

The magnesium oxide powder is then mixed with water to produce a slurry, through which air is bubbled in a stack, a small version of which is located in the laboratory.

In the process, the magnesium oxide (MgO) is combined with carbon dioxide (CO2) to produce magnesium carbonate (MgCO3), from which the water can be evaporated to leave the dry white solid, which can be used as a building material.

“You’re left with the open structure,” said Mr Evans. “You can create bricks and clad your house with it – it’s fireproof and thermally insulating.”

Nickel and cobalt, both used in electric car batteries, are separated out, as is silica, which has many uses, including in construction and tyre production.

As well as being used for DAC, the firm’s technology could capture CO2 released by industrial plants, a process known as carbon capture, utilisation and storage (CCUS).

CCUS facilities employing other technologies are already in operation, such as at the Emirates Steel plant in Abu Dhabi and at Aramco’s Hawiyah gas facility in Saudi Arabia, and their wider use is seen as necessary by some observers as long as industries that generate CO2 are active.

Growing industry

The CO2 removal sector is expanding, particularly in the US thanks to government incentives. The American authorities are spending $3.5 billion between 2022 and 2026 to establish regional DAC hubs.

“There’s now going to be a huge flow and I would expect that some of the other oil-rich countries, like Saudi Arabia and the other Gulf states, will start investing heavily in its development,” said Bob Ward, of the Grantham Research Institute on Climate Change and the Environment, part of the London School of Economics.

Many other analysts also say direct air capture could prove valuable.

Among them is Dr Artur Runge-Metzger, a former EU climate change negotiator who is now a fellow at the Mercator Research Institute on Global Commons and Climate Change.

“Direct air capture, where you have the first experiments in Iceland and so on, these are the things that need to be done and studied and the cost of these technologies need to come down in order to have sufficient breadth of technologies that you can deploy,” he said.

Alternative methods

Climeworks, a company in Iceland, has a plant named Orca that is described as the world's first large-scale CO2 removal facility. A second plant, Mammoth, is under construction.

The firms with a partner, Carbfix, that dissolves the CO2 in water, which is injected underground in Iceland into basalt rock, where it mineralises or solidifies over two years.

Another Climeworks partner, 44.01, is working on a method to mineralise the CO2 and inject it into another type of rock, peridotite, in Oman.

“Our commercialisation and large-scale deployment are on track to reach our key objective: to deliver multi-megatonne [CO2 removal] capacity in the 2030s and gigatonne capacity by 2050, as climate science requires,” a Climeworks spokesperson said.

To achieve massive scale up requires, the company said, more funding from the public and private sectors, the development of carbon markets (which put a value on removing CO2), supportive regulations and policies and a supply chain “able to deliver on enormous scales”.

Governments can support the industry, the company said, by, for example, acting as “a first buyer” for DAC products, while the firm has attracted private sector customers such as Microsoft and Swiss Re because of what it calls its “high-quality, permanent, and safe carbon removal solution”.

Climeworks is confident that its technology will achieve improvements in efficiency and cost similar to those seen in the renewable energy sector.

“Electric cars or solar photovoltaic are examples from the past that have followed exactly this trajectory, and there is no doubt that direct air capture will follow the same path,” the spokesperson said.

Cambridge Carbon Capture says that its methods, being based around the generation of valuable end products, make stand-alone DAC plants or the use of CCUS at industrial facilities cost-effective.

For every tonne of CO2 captured, products worth about $1,600 are generated, Mr Evans said.

DAC plants each cost an estimated $300 million to $500 million. The company said that public finance and carbon markets – in which carbon credits are bought and sold, thereby putting a value on emissions – only go so far in terms of funding such projects, making private investment essential.

Mr Evans said Oman would be a particularly suitable location for plants because the country is “awash with magnesium silicates”.

As well as being applicable on land, the process could capture CO2 emissions from ships, which account for around three per cent of global carbon emissions. Vessels could use seawater with the magnesium carbonate to permanently remove maritime emissions.

Cambridge Carbon Capture is looking to raise funds to expand its pilot project, construction of which is starting at Ely, a small city not far from Cambridge. Mr Evans is determined to see the project through to fruition.

“I feel duty bound to do it,” he said. “It’s like a call to arms really. Nothing else matters if we don’t have a planet to live on.”

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Updated: June 05, 2023, 6:06 PM