What CCUS Is and Why It Matters

Carbon capture, utilisation and storage (CCUS) is a group of technologies that stop carbon dioxide (CO2) from reaching the atmosphere. The CO2 is separated from a gas stream, made ready for transport, and then either used to make a product or stored permanently deep underground.

You will also see the shorter term carbon capture and storage (CCS). CCS means the CO2 goes into permanent geological storage. CCUS adds the option of using the CO2. In practice, almost all the CO2 that is stored today goes into rock formations one to three kilometres below the surface, and only a small share is used in products.

The idea is not new. The oil and gas industry has separated CO2 from natural gas for decades, and has injected CO2 into oil fields to produce more oil since the 1970s. What is new is the purpose: storing CO2 to reduce emissions, at a scale large enough to matter for the climate.

Hard-to-abate sectors

Many emissions can be cut by switching to renewable electricity or by using energy more efficiently. Some cannot. These are called hard-to-abate sectors.

• Cement. Most of the CO2 from a cement plant comes from heating limestone, which releases CO2 from the rock itself. Clean fuel does not remove this part.
• Steel and chemicals. These need very high temperatures and use carbon as part of the chemistry.
• Natural gas processing. Many gas fields contain CO2 that must be removed to meet sales gas or liquefied natural gas (LNG) specifications. That CO2 is released today unless it is stored.
• Hydrogen made from natural gas. The process produces a concentrated CO2 stream as a by-product.

For these sectors, CCUS is one of very few ways to cut emissions deeply while the plant keeps running.