Earth Day, the world’s biggest environmental protection event involving roughly 1 billion people from 192 countries. This year’s theme was Restore Our Earth and focused on the emerging technologies and innovative thinking that are helping to repair – rather than simply reduce – the damage we have done to our planetary systems. One such system is our climate and there is a growing climate restoration movement which aims to not only keep atmospheric concentrations of greenhouse gases (GHGs) in line with the Paris Agreement, but to go beyond that to return them to the same levels as the pre-industrial era.
Achieving pre-industrial GHG concentrations of roughly 300ppm of CO2 (as opposed to the ~415ppm we have today and the absolute upper limit of ~450ppm that aligns with the Paris Agreement) can only be achieved by creating a carbon deficit, simultaneously reducing emissions into the atmosphere and increasing the amount taken out. Historically, the latter has been achieved through enhancing and protecting natural carbon sinks, such as forests. However, there are a range of exciting technologies and processes now coming to the fore that can artificially remove carbon dioxide from the atmosphere and keep it there.
For example, Swedish company Climeworks has developed technology that captures CO2 directly from the air. Fans draw air into collectors where CO2 is captured on the surface of filters. Once full, these filters are heated to release the carbon dioxide which is then captured in a high-concentration, high-purity form. This can be permanently stored. Icelandic company Carbfix, for instance, is using geothermal energy to power the Climeworks technology and then mixing the captured CO2 with water and pumping it deep underground. Here natural mineralisation processes occur and the CO2 reacts with the basalt rock to turn into stone, thereby permanently removing it from the atmosphere.
Another technology that runs on similar principles is Klaus Lackner’s mechanical trees. These ‘trees’ are about 30 feet tall, have 150 discs instead of leaves, and require no energy to run. As the wind blows through them, the discs filter out carbon dioxide and, once full, the trees collapse in on themselves keeping the carbon to be stored. Both Climeworks and Lackner’s Trees use a form of technology known as Direct Air Capture (DAC) and, if you’re interested, both are going to be on display this summer in the London Science Museum’s Our Future Planet exhibit.
DAC technologies are one type of innovation that could help to restore the climate, but there are many others. Californian start-up Blue Planet has developed a technique that takes captured CO2 from flue gas and converts it into carbonate to make synthetic limestone, which can then be used in lieu of mined aggregate in concrete. Not only does this store the captured CO2 but it also prevents emissions from the mining of natural limestone – a win-win. Then there are new techniques to enhance existing carbon sinks, such as restoration of ocean pastures and marine permaculture. These involve encouraging the rapid growth of kelp forests and phytoplankton through the addition of limited minerals (such as iron) or through upwelling (i.e. use wave-powered pumps to bring nutrients to the surface). These can create diverse ecosystems that result in carbon sequestration when the remains of dead flora and fauna sink to the bottom of the ocean. Such processes are in the early stages of study and development, but they show promise.
All of these could play a vital role in limiting CO2 concentrations and may even bring them down to pre-industrial levels. However, it is not enough to simply undo the damage that has already been done, we have to limit the damage that we are continuing to do. As I mentioned earlier, restoring our climate will require creating a carbon deficit – it’s like calorie counting on a weight-loss diet. The technological innovations discussed so far are more akin to liposuction than to adopting healthy lifestyle changes. Liposuction can only be minimally effective if we don’t also limit the amount of carbon calories we consume. This is tricky, especially considering that by 2050 the planet will have an additional 2 billion people needing to be clothed, fed, housed, and entertained.
To extend the metaphor, the solution to a healthy climate is only eating what we need (i.e. using energy efficiently) and replacing high calorie inputs with low calorie substitutes (e.g. switching to renewable energy). But there are still many “foods” on which we currently depend for which viable low-carbon alternatives either don’t yet exist or aren’t widely accessible: certain industrial processes, for instance, or low-carbon transport, heat, and cement. For these, more traditional carbon capture and storage (CCS) could buy us vital time to develop low-carbon alternatives. Capturing emissions at source is much easier and faster than sucking CO2 from the air, and there is existing expertise – particularly in the oil and gas industry – for transporting captured CO2 and injecting it deep underground.
It’s not often that the oil and gas (O&G) industry gets to play a positive role regarding climate change, but CCUS offers an opportunity to do so. Depleted oil and gas fields can store huge quantities of CO2.They have been extensively studied and surveyed, so their capacity for carbon storage is both understood and quantifiable, and they are often well-serviced in terms of infrastructure and transport. Furthermore, the people who work in the O&G industry already have the necessary skills and experience for all elements involved in CCS. Indeed, CCUS could be an important part of a just transition to a low-carbon economy through providing gainful employment that suitably matches the existing skillsets of O&G workers.
There are many CCUS technologies that I haven’t had space to discuss here (blue hydrogen – for instance – could be a real game changer) but all offer the potential to help minimise the damage we’re doing to the climate and even help to repair the damage we’ve already done. Given the right finance and policy support, these technologies can be scaled up to remove the 1 trillion tons of CO2 that need to be sequestered by 2050 to meet the Paris goals. CCUS alone cannot solve climate change – liposuction can only do so much against an unhealthy lifestyle – but coupled with significant decarbonisation and improved efficiency, it might buy us the time we need to avert catastrophe.