The promise and challenges of four CCU applications

Carbon capture can offset emissions from hard-to-abate sectors and remove existing CO2 emissions from the atmosphere. After capture, carbon may either be stored (CCS) or utilised in other applications (CCU). CCS has attracted much of the investment and policy action to date. But CCU is enjoying growing attention because captured CO2 is recycled into other products, contributing to a more circular, less wasteful economy.

Four promising near-term applications

Today, more than 25 CCU applications are under development. Four stand out as most promising in the near term based on technological readiness, level of investment, and potential 2040 market size:

CO2-derived construction aggregates

Construction aggregates represent the largest potential market in terms of CO2 volume, utilising approximately 0.5 Gtpa of CO2 by 2040. Carbon is sequestered permanently in the aggregate product, creating a net climate benefit. Producing conventional construction aggregates emits 3 kg of CO2 per tonne. In contrast, CO2- derived aggregates using captured carbon can save 12 kg to 48 kg of CO2 emissions per ton, generating net savings of 9 kg to 45 kg per tonne. (Actual savings realised depend on transportation distances, preexisting waste streams, and energy sources.)

The greatest challenge to fulfilling the promise of CO2-derived aggregates is cost. Without landfill taxes, they are four to five times more expensive than their conventional counterparts, largely due to production and transportation costs.

CO2-cured concrete

Concrete is conventionally cured with water or steam. Using CO2 instead provides a stronger product and requires less cement, while permanently sequestering the CO2. Depending on various factors (e.g., transportation distances, amount of cement, energy source emission intensity), producing CO2-cured concrete emits 0 kg to 413 kg of CO2 per ton, compared to 240 kg to 420 kg for conventional methods. The technology is fairly mature and is already in use.

Several challenges may limit the widespread adoption of CO2- cured concrete. If conditions are not favorable, this method can be worse for the climate, even with utilised CO2. And because CO2- cured concrete can increase the risk of steel corrosion, its use is usually limited to precast structural components which constrain potential market size. A relatively small amount of CO2 is required to cure a ton of concrete, so its climate impact is also limited. And finally, CO2-cured concrete is 1.3 to 1.5 times more expensive than conventional versions, restricting its economic viability to specific circumstances.

E-kerosene and e-methanol

Unlike their conventional counterparts which are produced using fossil resources, e-kerosene (for aviation) and e-methanol (primarily for shipping fuel) both rely on electricity, CO2, and hydrogen for their manufacture. Carbon abatement potential is 30% to 98% for e-methanol and 0% to 98% for e-kerosene compared with conventional variants. Several large e-methanol and e-kerosene projects are scheduled to come onstream this decade.

Several factors may constrain these e-fuels’ ability to utilise CO2 at the upper end of the estimated ranges. Unlike the applications discussed earlier, which permanently sequester carbon, e-kerosene, and e-methanol both emit CO2 back into the atmosphere when burned as fuels. This means that their CO2 feedstock must come from biogenic – not industrial – sources or direct air capture (DAC) before either could be considered carbon neutral.

Their production would also require low-carbon or renewable power and green hydrogen. Additionally, low-carbon alternatives to both e-fuels are årequire additional infrastructure, and regulations must be introduced supporting the use of these fuels. Cost will be a factor as well: they are two to four times more expensive than conventional variants, depending on prevailing subsidies. Carbon prices of US$180 and US$330 per ton respectively would be required to make them commercially feasible.

Regulation will be key to economic viability and growth

CCU is an important means for limiting carbon in the atmosphere. But its decarbonisation impact is highly dependent on application, the source and proximity of the utilised CO2, relative efficiency of the production processes, and whether CO2 is emitted during use. And its greatest challenge to widespread adoption is cost. CO2- derived products are up to four to five times more expensive than their conventional counterparts.

The size of the CCU market could in time be meaningful, with some estimates placing it at 10% to 33% of total captured carbon by 2050. But fulfilling this promise requires a supportive regulatory environment, including financial incentives, carbon pricing, public procurement targets, and better carbon-accounting rules and emission measurement mechanisms. Collectively, these can improve the economics of applications, support scaling, and establish CCU as a meaningful, long-term decarbonisation lever.