2024-03-18 03:56:26
Nothing seems to be able to stop the increases in CO2 emissions into the atmosphere. Methods for storing it or eliminating it once in the air are being studied.
The delay taken by humanity in reducing its greenhouse gas emissions, which broke a new record in 2023, has propelled to the forefront technologies for removing and storing CO2 from the atmosphere for try to limit global warming. Two families of different and sometimes confused methods exist: on the one hand, carbon capture and storage (CCS, in English) and, on the other hand, direct capture in the air (DAC, in English), also called carbon removal.
Should we prevent carbon from “polluting” the atmosphere or “clean it up” once the damage is done? These are the two distinct roles of the CCS and the DAC. The CCS captures the carbon emitted by the combustion of fossil fuels or by industrial processes at the outlet of factories (power plants, cement plants, blast furnaces, etc.) before it enters the atmosphere. The DAC extracts the CO2 already present in the air, via large fans and chemical processes.
The technique thus makes it possible to count “negative emissions” in the carbon balance of companies or countries that use it, provided that the captured CO2 is stored permanently, for example in depleted oil and gas reservoirs or in saline aquifers. The CO2 molecules present in the air are, however, much more diluted – 420 parts per million (ppm), or around 0.04% – than at the outlet of a factory chimney, which makes the technique energy-intensive. and expensive. In both cases, the captured CO2 can be permanently stored or reused to manufacture construction materials or aviation fuel. But reuse means an inevitable return to the air and can no longer be counted as disposal.
Massive investments
The fossil fuel industry has used CCS since the 1970s…but not to stop carbon from seeping into the atmosphere. Originally, this process was used to inject CO2 into old fields to extract oil that was difficult to access. But the climate crisis and public subsidies have revived the interest of fossil fuel industries in using it to reduce emissions, even if it remains unprofitable.
By the end of 2023, 40 commercial companies around the world were applying this technology, capturing a total of 45 million tonnes (Mt) of CO2, according to the International Energy Agency (IEA). Or around 0.1% of annual global emissions. Carbon removal (CAR) is more recent. Fewer than thirty installations use it worldwide, capable of extracting around 10,000 tonnes of CO2 per year, the equivalent of 10 seconds of global emissions.
To achieve the goal of net zero emissions by 2050, the CCS will need to prevent 1.3 billion tonnes of CO2 emissions per year by 2030, or 30 times more than currently, estimates the IEA. As for the DAC, it will have to extract 60 million tonnes of CO2 per year by then, thousands of times more than today. If this seems out of reach, recent developments offer some hope: at least 130 projects are under development, according to the IEA, and the first plant capable of capturing up to one million tonnes per year is due to come into operation. in the United States in 2025.
“A huge challenge”
“It’s a huge challenge, but it’s not unprecedented,” says Gregory Nemet, professor at the University of Wisconsin, recalling the spectacular growth of solar power in just a few decades. There remains the question of storage: preparing a site can take up to 10 years, a significant obstacle. CCS costs 15 to 20 dollars per ton when CO2 emissions are very concentrated, and 40 to 120 dollars per ton for more diluted flows, as in electricity production. On the DAC side, costs are higher, from $600 to $1,000 per ton of CO2. But they are expected to fall toward $100 to $300 per ton by 2050, according to the State of Carbon Dioxide Removal report.
Recent laws in the United States and Canada rely on tax credits to encourage companies to invest, while South Korea and China are investing massively. A factory aiming to capture 500,000 tonnes of carbon per year has just opened in the Chinese province of Jiangsu. Canada has extended an investment tax credit that cuts the cost of CCS in half. In the United States, the Inflation Reduction Act (IRA) provides billions of dollars in tax credits for CCS.
Europe is not left out, with a veritable “CO2 cemetery” developing in the North Sea. For the DAC, many major companies – Alphabet, Shopify, Meta, Stripe, Microsoft and H&M – plan to contribute almost $1 billion towards “permanent removal” of carbon by 2030. Earlier this month, Climeworks, pioneer of DAC based in Switzerland, announced an agreement to sell carbon emission credits to two airlines, Swiss and Lufthansa.
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