How advanced is technology to absorb carbon dioxide – and could it slow climate change? IG News

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To limit global warming to 1.5 °C, humanity would have to remove 660 billion tonnes of carbon dioxide (CO₂) from the atmosphere by the end of the century. This is in accordance with the most recent report by the Intergovernmental Panel on Climate Change (IPCC), which based its estimates on atmospheric CO₂ concentrations measured in 2020.

Removing that much CO₂ would involve much more than just planting a lot of trees. Engineers and scientists are developing Direct Air Capture Technology (DAC), which pulls large amounts of CO₂ out of the atmosphere while using very little land and water.

A typical DAC unit uses large fans to push air through a liquid or solid material that can bind and remove CO₂, just as human lungs expel oxygen. The material regenerates when heated, releasing concentrated CO₂.

Concentrated CO₂ can either be stored permanently, typically underground in depleted oil and gas reservoirs, or used to produce useful chemicals such as synthetic fuels. These fuels will release CO₂ again when burned and are therefore technically carbon neutral.

Advocates of the technology say it could reduce the need for fossil fuels and help industries that are difficult to decarbonize, such as aviation, reach net zero emissions. Others worry that the DAC distracts from the hard work of reducing carbon emissions.

These critics suggest that the high energy cost and materials used for the DAC make it extremely expensive and so impractical that over the tightrope times left to avert catastrophic climate change. The cost of removing one ton of CO₂ with a DAC can reach US$600 (£522).

DAC technology is still in its infancy. The International Energy Agency (IEA) estimates that it will remove 90 million tons per year in 2030, 620 million tons in 2040 and 980 million tons annually in 2050.

But as things stand, only 19 DAC projects have come online since 2010, which collectively remove 0.008 million tons of CO₂ each year, the equivalent of about seven seconds of global emissions from energy production in 2021.

A DAC unit in Canada.
David Buzzard/Shutterstock

DAC developers are working on projects that will remove approximately 1 million tonnes of CO₂ each year in mid-2020. But they may struggle to improve energy efficiency and reduce costs rapidly enough to remove CO₂ on the scale needed to meet the IEA’s forecasts for 2030. Why over here

DAC deployment is gaining momentum

The largest unit currently operating is the Orca plant, which was built in Iceland in 2021 by the company Climeworks. As big as two shipping containers, Orca aims to dissolve and sustainably store 4,000 tons of CO₂ annually in water. It is underground where it will react to form rock.

In a year, 170,000 trees are absorbed on 340 hectares of land. Unfortunately, cold weather in early 2022 forced the machinery to shut down and shut down the plant.

Carbon Engineering, another DAC developer, plans to deploy a unit in the US to Texas, which it says will remove and store 1 million tons of CO₂ a year once it begins operations in 2024. This venture involves an investment of several million dollars. From United Airlines which is attempting to offset emissions from its flights as well as acquire synthetic fuel.

The carbon-neutral fuel can replace oil in airplanes and long-haul freight vehicles. But air-to-fuel technologies still require a more competitive business model than the fossil fuel industry.

This is unlikely to happen quickly, as the latter is so well established and subsidized, while the technology behind air-to-fuel is rudimentary and requires substantial investment to scale up.

Cost is falling very slowly

The IEA has estimated that removing 1 billion tonnes of CO₂ per year from the air with DAC plants in 2050 will consume 1,667 terawatt-hours of energy – the equivalent of 1% of global consumption in 2019.

CO₂ costs are expected to drop to between US$125 and US$335 per tonne by 2030, with the potential to drop below US$100 by 2040. This would depend on the deployment of the DAC units and the developers learning from these demonstration units, similar to how the cost of solar power fell over time.

DACs could become economically viable in the 2030s if falling costs are met by rising carbon costs in tax regimes. According to the International Monetary Fund, in countries where carbon taxes or pricing mechanisms exist, the average price of CO₂ is expected to reach US$6 per ton in 2022 and is expected to rise to US$75 by 2030.

The EU Emission Trading System had set the price of one tonne of CO₂ at US$90 per tonne in 2022. The Inflation Reduction Act recently increased the tax credit for companies that remove and store CO₂ in the US from US$50 per tonne to US$180.

But higher carbon prices elsewhere are far from ideal. In China, carbon prices ranged between US$6 and US$9 per tonne in 2021 and 2022.

Smoke rising from the chimneys of the coal power plant.
Carbon emissions are still very cheap.

DACs may also be viable if the removal of CO₂ is monetized. But this is risky. One application of DAC is augmented oil recovery, which involves pumping concentrated CO₂ underground to extract more oil.

Estimates suggest that this method could emit 1.5 tons of CO₂ for every ton removed. While this strategy may reduce the net emissions of conventional oil production, it will still add carbon to the atmosphere.

Opportunities may arise in industries that require concentrated CO₂, like food manufacturers. The price of CO₂ has increased from US$235 per tonne in September 2021 to US$1,200 recently.

This is because most of the CO₂ in the UK comes from the fertilizer industry, where rising natural gas prices have wreaked havoc. Although current global demand is limited to around 250 million–300 million tonnes per year, DAC may soon offer a more economical and climate-neutral supply of CO₂.

New technologies could help make DACs cheaper. For example, a DAC start-up in the UK called Mission Zero Technologies aims to use electricity instead of heat to regenerate CO₂-absorbing materials in DAC units. The company claims that this will cut the energy requirements of the DAC by four times.

Unfortunately, cost estimates for DACs are highly uncertain. This is partly because they often come from the developers themselves, rather than from independent research. There is no generally accepted approach to quantify the actual costs of DACs, but my research group is working with a global network of academics and industrialists to verify the removal costs claimed by DAC developers and forecasts by the IEA. Is.

Will DAC Slow Global Warming?

The world needs to build about 30 DAC plants capable of removing more than 1 million tons of CO₂ every year between 2020 and 2050. With only a few such plants expected to be operational by mid-2020, it will be difficult to bridge this gap, especially if costs remain high and DAC technologies are not discovered and commercialised.

I believe that DAC is still an essential tool for slowing global warming. When projected cost reductions are achieved, DAC will open the way for large-scale CO₂ removal with a much smaller land and water footprint than other removal technologies in 2030 and beyond.

The role of the DAC is not to offset rising emissions in the 2020s, but to close the emissions gap and reduce atmospheric CO₂ concentrations to limit global warming to 1.5 °C during the decade and closer to 2050 . This is why governments and businesses should focus on ending their reliance on fossil fuels while supporting research and development of DAC technology to reduce their costs.