Opinion: Is Carbon Removal an Effective Technology in our pursuit of Net Zero?

Climate change is primarily caused by carbon dioxide (CO2), the main greenhouse gas that results from the combustion of fossil fuels. Carbon dioxide removal (CDR) encompasses various technologies that can capture CO2 emissions and permanently store them, preventing their release into the atmosphere and contribution to climate change.

CDR is seen as a promising approach to help mitigate climate change by reducing the concentration of CO2 in the atmosphere. While traditional methods of reducing CO2 emissions, such as renewable energy and energy efficiency measures, are crucial in achieving climate goals, they may not be enough to reach net-zero emissions. CDR technologies such as ‘Direct air capture’ (DAC) can help fill this gap by removing CO2 that has already been emitted into the atmosphere, enabling the world to achieve its climate targets.

These technologies work via the use of large-scale machines or fan-like devices that are designed to capture CO2 from ambient air, concentrate it with the help of chemical sorbents (i.e. sodium hydroxide), and store it for later use or disposal. The captured CO2 can be stored in underground geological formations, used in industrial processes, or utilized to produce fuels and other products. The causticizing process is shown below.

The Nitty-Gritty

Carbon dioxide removal is essential for achieving net zero emissions, which is required to limit global warming to 1.5-2°C above pre-industrial levels. While the Intergovernmental Panel on Climate Change has identified pathways that involve rapid decarbonisation, it is not feasible to completely eliminate carbon emissions within the necessary time frame. This is particularly true for industries such as aviation and shipping, which are difficult to decarbonise. Therefore, residual emissions will remain, making it impossible to achieve a zero-emissions goal without CDR. In the past, this has involved planting trees, but the most effective approach will be to remove CO2 from the atmosphere and store it in the ground, the ocean, or in products, as this will be more sustainable in the long term.

There has been an emergence of businesses that offer various CDR techniques as climate solutions, while others are investing in carbon credits as part of their decarbonisation commitments. While I acknowledge the importance of developing CDR methods in the long term and appreciate government investment in this area, I believe that the deployment of direct air capture (DAC) technology to remove CO2 from the atmosphere is futile until we have significantly reduced our polluting activities. Currently the UK government has successfully funded some small-scale demonstrations of DAC technology, but their deployment for CO2 removal would not be effective until society has almost entirely eliminated its polluting practices.

Going Back in Time 🕰️

Think of carbon dioxide removal as a time machine to fully understand why it is currently ineffective. For example, let’s imagine that the UK develops a direct air capture (DAC) technology, which is expected to extract one million tonnes of CO2 each year. In 2022, the world emitted 40.5 billion tonnes of CO2, meaning that for every year of operation at full capacity, the technology would only take the atmosphere back in time by just over 12 minutes! Unfortunately, within the time it takes to remove those 12 minutes of CO2, the world will have emitted another full year of CO2 into the atmosphere.

In contrast, if the entire population of Earth each planted a single tree, it would take us back in time by approximately 42 hours each year; once the 8 billion trees fully matured. The analogy of a time machine illustrates the impracticality of CDR at present. Therefore, it is essential to shift the narrative urgently and direct funding towards more effective climate solutions instead of deploying CDR as a solution today while emissions remain high, as if it were a substitute for immediate, radical emission reductions.

A Multifaceted Approach 🎯

If we manage to significantly reduce emissions in the next few decades, carbon dioxide removal could become more effective. For example, if we reduced emissions to just a tenth of current levels, a DAC plant capable of removing one million tonnes of CO2 would have a greater impact, taking us back over 120 minutes instead of just 12 minutes. However, even if we manage to reduce emissions, residual emissions will likely still exist, and we will need to scale up CDR significantly to reach net zero. This could involve building over 7,000 DAC hubs worldwide or using other CDR technology.

It is important to research and develop CDR methods that are efficient, scalable, and environmentally friendly. However, it is important to note that not all techniques that work in the laboratory will be successful in the real world, and some could have negative effects on biodiversity and the environment. It will take years of scientific research to determine which methods are effective and sustainable. It is also worth noting that DAC technology is very energy intensive.

It is crucial to remember that historically, we have only been able to eliminate atmospheric pollutants by shutting down their sources and letting nature take its course. Therefore, we must also prioritise rapid decarbonisation efforts in addition to developing CDR methods. The challenge ahead is immense, and we must slow down the clock on carbon emissions before we can turn it back.