In addition to storage, CO2 can also be used in industrial processes as a valuable feedstock to realize value, such as for Enhanced Oil Recovery (EOR) in the hydrocarbon sector or through mineralisation. It is, however, important to note that such use is limited in scope, that they may help improve the business case for CCS but that the end goal of CCS remains storage.
CO2 used for EOR has the ability to act as an incubator for the nascent CCS industry, providing real-world experience, customers for CO2 technologies, development of CO2 infrastructure and, critically, providing a wide variety of engineers, technicians and operators with the skills necessary to store CO2 .
CO2 has been used in commercial EOR projects since the early 1970s. In simple terms the process involves the injection of CO2 into a mature oil reservoir. The CO2 mixes with the oil, increasing the oil’s mobility, resulting in additional oil recovery and greater ultimate resource extraction. Some of the CO2 injected for EOR will remain stored for thousands of years, but in current operations CO2 is recycled back into the reservoir.
CO2 -EOR has been most extensively deployed in the USA. Here, over 2,414 km of CO2 pipelines have been developed to transport CO2 from natural sources to oil fields. Increasingly, anthropogenic sources of CO2 are being used to supply rapidly growing CO2 demand, such as CO2 from ethanol and ammonia fertilizer plants. In Canada, the Boundary Dam CCS project supplies CO2 for EOR. Revenue generated through the recovery of oil will help enable early CCS projects to have a more robust business case, easing financing and increasing the probability of a positive final investment decision.
CO2 -EOR, when deployed at scale, will also provide the foundations for dedicated CO2 storage sites. As CO2 -EOR projects grow in scale, dedicated CO2 storage operations will be needed to manage the varying CO2 demand intrinsic in CO2 -EOR campaigns. CO2 -EOR can play an important role in leveraging CCS deployment in Europe. However CO2 -EOR alone will not alone drive the large scale deployment of CCS, and it should be regarded as a part of a wider system of incentives to enable the first commercial CCS projects.
CO2 mineralisation is another form of CO2 utilisation whereby a variety of materials can be produced using CO2. The conversion of CO2 to useful saleable materials such as building products is attractive in some cases. However, it is not anticipated that such processes will be effective in capturing large amounts of CO2 globally. This is due to the huge scale of global CO2 emissions; the mineralisation of CO2 from an average power plant would result in many millions of tonnes of product that would need to be transported and disposed of.