Carbon capture and net zero

July 26, 2023

Tim Miles

In their special report on Carbon Capture, Utilization and Storage (CCUS), the International Energy Agency made the bold claim that “reaching net zero will be virtually impossible without CCUS”.[1] In plain figures, according to the IEA, this means that CCUS technologies will need to capture and store up to 7.6 gigatons of CO² per year by 2050, up from less than 40 million tons captured and stored in 2020, when there were a mere 20 commercial CCUS operations worldwide.

Government backing worldwide

Even today there are many more initiatives in place, often driven by Government initiatives such as the 45Q tax credits available in the USA and the EU’s Green Deal.[2] There are also a number of technologies already available, with others under development.

In these initial stages of CCUS technology deployment, much of the attention is focused on capturing carbon emissions at source in facilities such as fossil fuel-based power and industrial plants, including those that support hydrogen production. This has the advantage of being capable of being retrofitted to existing cement works, oil refineries and other high carbon-emitting plants to achieve rapid results.

Cost and other factors

The cost of capturing carbon from source points can be relatively inexpensive. In the USA, the Inflation Reduction Act and 45Q tax credits provide subsidies of up to $85 per ton of carbon captured from emissions. The economics of carbon capture, however, is more complex than simply calculating the cost of capture itself. Other factors include the availability and ease of access to storage points, the method of storage, or the use of carbon in other processes.

Readily available storage sites

Potential storage sites range from exhausted oil fields and coal seams to the ocean floors, using well-established techniques that use much of the same tools and skillsets that enabled the extraction of resources such as oil or coal. Carbon utilization, rather than storage, opens up the intriguing possibility of using the carbon in other processes – such as the production of hydrogen or synthetic fuels – with the carbon then recaptured as part of the process.

Direct carbon capture needed

Although source point capture is easily achievable, it is not enough to achieve the net zero targets the world needs to hit by mid-century. Direct air capture (DAC) technologies are needed to extract carbon directly from the atmosphere. As of 2022, there were 18 DAC facilities in Europe, Canada and the USA. Most of these are capturing carbon for sale in other processes, such as the carbonization of drinks.

Investment in DAC is growing. In the USA – currently the world’s leading country for CCUS[3] – $3.5 billion is being used to develop four DAC hubs, according to a 2022 IEA report.[4] The EU’s Green Deal Industrial Plan puts Carbon Capture and Storage at its heart. Individual countries also have their own initiatives, with the UK putting £1 billion into funding for the technology[5] and Norway’s Longship and Northern Lights projects benefitting from €2 billion in Government investment.

Current technology

The technology that’s currently available splits into two categories: solid and liquid DAC, or S-DAC and L-DAC. Methods based on S-DAC use solid adsorbent materials – such as the zeolites Li-X and Na-X – that can operate at ambient or low/zero pressure in the temperature range of 80-120°C. In L-DAC processes, the liquid used to capture carbon is typically an aqueous solution such as potassium hydroxide. L-DAC processes work at much higher temperatures, in the range of 300-900°C.

Future trends

Both S-DAC and L-DAC processes are more expensive than point source capture, and both use far more energy. This is, quite simply, because carbon in the open atmosphere is less prevalent than in the concentrated levels found inside, say, a factory chimney. Other technologies on the horizon include a solid electrochemical cell that switches from positive to negative to capture carbon (ESA) or a membrane processing high quantities of air under high pressure (m-DAC).

From cost to profit

Currently, CCUS is a cost with little opportunity to turn into revenue. Some uses – such as enhanced oil recovery or the production of plastics – could be viewed as adding to some of the world’s environmental challenges rather than mitigating them. Other potential revenue opportunities are in the very early stages, such as Stanford University’s research into the possibility of using carbon to create zero-emissions fuels.[6]

Setting standards

However the technology develops, globally accepted standards for carbon capture will need to be established. The EU’s Carbon Removal Certification Framework[7] is a voluntary standard that goes toward establishing some norms, but it is neither compulsory nor globally accepted. In the meantime, we’re still a very long way from achieving the necessary CCUS capacity that is an essential part of the global net zero transition.