Carbon emissions are the reason climate change is happening. The Intergovernmental Panel on Climate Change says that we have until 2050 to reach net zero carbon emissions to avoid the worst of its effects – floods, droughts, forest fires, mass extinctions, and more. This means that by 2050, we have to absorb back every molecule of carbon dioxide we produce. There are several ways we can do that, the most common of which is by planting trees. Trees naturally take the carbon dioxide in the air and convert it to oxygen during the process of photosynthesis.
But at this point, relying on trees isn’t going to be enough. The world is producing carbon emissions at an ever-increasing rate. We released over 36 billion tonnes of carbon dioxide in 2019, compared to the 25 billion tonnes in 2000. Renewable energies like solar and wind have made transitioning away from fossil fuels easier. But if there was another way to capture back carbon dioxide, like trees do, it would definitely help a lot to fight climate change. It would be like hitting “undo” on centuries of carbon emissions.
Is there a way?
Enter carbon capture. Over the past few years, it’s been gaining more and more attention. Oil companies are talking about it. Scientists are too. Even Elon Musk is promising a $100 million prize for the best carbon capture technology. Several startups have already built experimental plants to collect carbon dioxide from the air. Three of them are Canada’s Carbon Engineering, Switzerland’s Climeworks, and the U.S.’s Global Thermostat.
But this technology isn’t as revolutionary as we think. Carbon capture was first used in the 1920s to separate carbon dioxide from methane gas. Carbon capture technology has only recently been promoted as a solution to climate change.
How it works
There are three main ways of capturing carbon dioxide: post-combustion carbon capture, pre-combustion carbon capture, and oxy-fuel combustion carbon capture.
Post-combustion carbon capture happens after the burning of fossil fuels. This produces water vapor, sulfur dioxides, nitrogen oxides, and carbon dioxide – which is separated from the others and captured. This method is great because it’s super easy to incorporate into power plants. It only needs a filter and can prevent 80-90% of a plant’s carbon emissions from entering the air. One downside is that it costs a lot to compress the carbon dioxide for transport.
Pre-combustion carbon capture happens before the burning of fossil fuels. Instead, the fossil fuel is heated in pure oxygen to produce carbon monoxide and hydrogen. Another chemical reaction converts the substances to hydrogen and carbon dioxide, then isolates it. This method costs less and makes more carbon dioxide, but can’t be added to existing power plants. It prevents a similar amount of carbon emissions from entering the air as post-combustion.
Finally, oxy-fuel combustion carbon capture burns the fossil fuels in pure oxygen, which produces water vapor and carbon dioxide. The two gases are then separated through a process of compressing and cooling. The oxygen used in this way is costly, but researchers are working on bringing the cost down. This method prevents a whopping 90% of carbon emissions from entering the atmosphere.
Oh, and there’s one more way:
Startups have also developed a new way of carbon capture – collecting carbon dioxide from the air in a process called direct air capture. Using massive filters that catch the molecules, the carbon dioxide then goes through a purification process. Like all other methods, it recycles or stores the isolated carbon dioxide deep underground. Direct air capture is also currently very costly and energy-intensive. However, these plants do lower transportation, water, and land footprints.
Politicians and scientists alike have conflicting views on carbon capture technology.
On one hand, researchers are worried about the “moral hazard” of carbon capture. Fossil fuel plants will have less pressure to stop emissions if there’s an undo button waiting. In 2016 a paper published in the Science journal warned that “negative-emission technologies are not an insurance policy, but rather an unjust and high-stakes gamble.” Prominent politicians like Bernie Sanders have called carbon capture a “false solution”.
On the other hand, in 2018 the Intergovernmental Panel on Climate Change showed in a report that every way that limits global temperature increase to 1.5 degrees Celsius requires some form of carbon capture. In 2020, another report published in Scientific Reports concluded that even if we stopped all carbon emissions right now, global temperatures would still rise, bringing catastrophic consequences to the world. Other politicians like Andrew Yang, Pete Buttigieg, and Amy Klobuchar support funding carbon removal technologies.
The future for carbon capture
It’s becoming increasingly clear that the world’s carbon emissions are racing towards a disastrous amount. We have already passed the threshold where it would still be possible to reduce emissions and avoid the consequences of climate change. I think even though carbon capture is a gamble, extreme situations need extreme solutions. At this point, anything that can bring down carbon dioxide levels in the atmosphere is worth the risk.
I also think that any innovation benefits humanity. Even if carbon capture doesn’t live up to its promises, the time and resources poured into research won’t go to waste. Its potential to reimagine fossil fuel plants and reverse carbon emissions is a much-needed stepping stone towards a future of clean energy.