Aug 27, 20238 min read

Carbon Capture: Can It Really Fix Climate Change?

Last month was the hottest ever recorded on Earth. It is a fact that the planet is heating up and, without drastic action, the changing climate threatens to unleash a wave of global disasters. Human activities are responsible for this and, while we are taking some gradual steps to become greener, we still generate most of our energy by burning heat-trapping carbon.

But what if, in addition to reducing our carbon dependency, we could undo some of the damage we’ve already inflicted? Imagine if we could clean up the atmosphere by removing harmful emissions after they’ve been pumped out – like a power plant operating in reverse. That’s the potential of new carbon capture technologies. Or at least, some believe it is…

The role of carbon capture in the global effort to tackle climate change is hotly debated. Could this be an essential technology that helps to save our planet? Or is it a convenient distraction for businesses and governments to hide behind instead of tackling the root causes of global warming?

Watch my short video to find out more…

What is carbon?

With so much focus rightly on how our carbon-dependency is impacting the planet, it’s only fair that we also acknowledge some of the positives. For starters, it is one of the key building blocks for all known life on Earth (as positives go, that feels like a pretty big one…)

One of the important things to understand about carbon is that it is incredibly versatile. It’s the fourth most abundant element in the observable universe and, due to the numerous different ways it can bond with other elements, it takes many different forms – from coal to diamonds, graphite to gases. It’s in our bones (about 12% of our bodies are carbon), the air that we breathe, the food that we eat and most of the materials we use to make things like plastics, rubber, cotton and concrete.

Carbon dioxide (CO2) is released into the atmosphere naturally when we breathe, when plants decay and when volcanoes erupt. While it only accounts for a small proportion of the air around us – about one molecule in every 2,500 – it has a huge impact. As Earth’s most prevalent greenhouse gas, CO2 helps us to retain some of the heat we receive from the Sun. Without it, our planet would completely freeze over.

So far, so good. But things start to get a bit more complicated when we have too much of it in the atmosphere…

Chaos in the carbon cycle

There is a fine balance between things on Earth which emit CO2 (like volcanoes, animals breathing and things decomposing) and those which remove it (like plants and trees). This finely calibrated carbon cycle determines how much CO2 is in our atmosphere.

For thousands of years, that level remained pretty consistent. Left to nature’s own devices, CO2 locked away in oil and coal would be released back into the atmosphere over millions of years.

But that all changed a couple of centuries ago when humans started burning fossil fuels at an unprecedented rate. Following the industrial revolution, we became reliant on these carbon-based fuels to drive many of the advances in science and technology that we can so easily take for granted today – from central heating, hot water and electricity to cars, aviation and industry.

All of this meant that millions of years’ worth of CO2 was released back into the atmosphere in what amounted to a geological blink of an eye. As this extraordinary graph shows, CO2 levels have sky-rocketed:

A graph that says "for millennia, atmospheric carbon dioxide has never been above this line", with an abrupt rise beyond the line from 1950 onwards.

There is 50% more CO2 in the Earth’s atmosphere today than 200 years ago. We now know that this is causing the planet to heat up and, left unchecked, the consequences will be disastrous. As NASA warns:

If fossil-fuel burning continues at a business-as-usual rate, such that humanity exhausts the reserves over the next few centuries, CO2 will continue to rise to levels of order of 1500 ppm [more than treble the rate today]. The atmosphere would then not return to pre-industrial levels even tens of thousands of years into the future.

Net zero ambitions

To tackle this climate emergency, a growing number of countries, business and other institutions have pledged to work towards cutting greenhouse gas emissions (which, remember, are largely CO2) to as close to zero as possible, with any remaining emissions re-absorbed from the atmosphere.

The Earth is now 1.1°C warmer than it was in the late 1800s. To keep global warming to no more than 1.5°C – the target agreed by nearly every nation on Earth in the 2015 Paris Agreement – the United Nations says that global greenhouse gas emissions must fall 45% by 2030 and reach net zero by 2050.

And how is that going so far? Well, not all that great.

The world’s governments may be signed up to the net zero ambition, but taking action to get there is proving a lot more difficult.

Commitments made to move away from burning carbon fall "far short" of what is required. And that pledge to cut emissions 45% by the end of the decade? Not only will we miss it, but emissions are actually on track to increase by 10%.

So, what else can we do? One option is to explore the potential for greater action on the other side of the carbon cycle – removing CO2 that’s already in the atmosphere.

Carbon capture: Trees vs tech

There’s an estimated three trillion trees on Earth and they play an essential role keeping the carbon cycle in check. Trees absorb CO2 from the atmosphere, bind the carbon up in sugar which they use to grow, and then release the remaining oxygen for us to breathe. Carbon is stored in wood where it stays for decades or even centuries, until the tree dies and decomposes.

If this miracle of nature can help decarbonise the atmosphere for us, why would we need to engineer new technology to do it?

Planting more trees is undoubtedly a good thing to do. But this comes with its own challenges.

A typical mature tree is thought to remove about 22kg of CO2 from the atmosphere every year. A rough but very educated estimate suggests that we would need another 200 billion trees just to absorb emissions from the United States.

Scale that up to tackle this global crisis, and we’d need a total reforestation of a sizeable chunk of the planet. But even this would be unlikely to work in practice. Climate change is already leading to more trees burning down in wildfires, and the creation of new ecosystems is fraught with complexities and the potential for unintended consequences.

We definitely need to be protecting the forests and woodland we have while planting new trees. But to drive a significant increase in carbon capture – might technology be our best bet?

"1,000 times more efficient than trees"

On a grassy plain about 20 miles to the east of the Icelandic capital Reykjavik, there is an industrial-looking structure the size of two shipping containers. If the developers behind it are correct, these buildings may soon become a common sight across the world and a vital tool in our armoury for tackling climate change.

Climeworks’ Orca plant is the world’s biggest CO2 removal facility. It can capture up to 4,000 tonnes of CO2 per year through geothermal-powered fans. Using a method called direct air capture (DAC), CO2 is trapped as air blows through chemically-treated filters and is then heated, piped and stored underground in basalt rock.

It is claimed that this technology can capture 1,000 times more carbon than an equivalent forest of trees planted in the same space.

That may sound impressive, but consider that the 4,000 tonnes of CO2 captured by Orca is about the same as the annual carbon footprint of just 250 Americans, with the process costing an eye-wateringly expensive $1,200 per tonne. Clearly, there is a very long way to go before this technology is making a meaningful impact in tackling the climate crisis.

But for Climeworks CEO Jan Wurzbacher, the real significance of Orca is the proof that the concept works. With this important milestone cleared, scaling up, greater efficiencies and reduced costs should follow. The firm is now building a much bigger direct air capture and storage plant – Mammoth – capable of capturing up to 36,000 tonnes per year.

A dangerous distraction?

Not everyone is convinced by carbon capture, and there are some good reasons to be wary of its potential being overstated.

When UK Prime Minister Rishi Sunak announced a £20 billion investment in carbon capture earlier this month – alongside more than 100 new licences to drill for oil and gas – the response from environmental campaigners was damning.

It taps into a wider fear that a technology which hasn’t yet been proven at scale could distract attention and investment away from the most important action the planet needs to be taking – releasing less carbon into the atmosphere in the first place.

Ajay Gambhir is a senior researcher at the Imperial College Grantham Institute for Climate Change and author of a 2019 paper on the role of DAC in climate mitigation. He argues that direct air capture technologies are going to be essential but he also fears that unrealistic expectations could be counterproductive:

If you think DAC is going to be there in the medium to long-term, you will not do as much near-term emissions reduction... If the scale-up goes wrong – if it turns out to be difficult to produce the sorbent, or that it degrades more quickly, if it's trickier technologically, if turns out to be more expensive than expected, then in a sense by not acting quickly in the near-term, you've effectively locked yourself into a higher temperature pathway.

Others take an even stronger view and doubt that it can be scaled up in time to make a meaningful difference, pointing to the high costs and potential for the captured carbon to leak. Writing in New Scientist, environmental engineer Mark Jacobson strongly argued against betting on green tech solutions to save the planet:

Carbon capture, direct air capture and blue hydrogen – which all require equipment and energy – increase air pollution, relative to using the same money to replace fossil fuels with renewables, while scarcely reducing CO2. To solve our problems, we need to avoid policies that divert funds from true solutions. We must educate the public and policymakers about what works and what doesn’t, and thus overcome the misinformation that has distracted us to date.

Reasons to be cheerful?

The best way to tackle climate change is an obvious one – stop releasing greenhouse gas emissions like CO2 into the atmosphere.

But, given how urgently we need to act to prevent a disastrous temperature rise, carbon capture technologies will surely have an important role to play alongside a global shift to renewable energy. This, at least, is the view of UN scientists who say that advances in technologies like direct air capture are going to be essential if we are to meet our global targets to limit climate change.

There are also some encouraging signs that governments are starting to listen to concerns by legislating to ensure that investment in carbon capture complements the switch to renewable energy rather than distracting from it. In 2019, Sweden become one of the first countries to establish separate goals for cutting emissions and carbon removal. The European Union has followed suit with a similar law, which states that the overwhelming majority of action needs to come from reducing emissions, with carbon removal helping to go the extra mile.

Carbon capture technologies are not going to solve the climate crisis. But even a small contribution to saving the planet would be enough to make them essential.