Mineral Carbonation and Other Uses of Carbon Dioxide

The potential deleterious impact of unchecked anthropogenic climate change is now well accepted. Moreover, it is also clear that CO₂ capture and sequestration (CCS) is an important part of the portfolio of tools which can be used to mitigate anthropogenic CO₂ emissions whilst concurrently maintaining appropriate standards of living around the world. However, in the absence of a binding international agreement or high carbon price, the deployment of CCS suffers from a strong first mover disincentive. It is in this context that CO₂ capture, and utilisation (CCU) or conversion (CCC) are typically mentioned, the main idea being that this is a potential option to add value to captured CO₂.

In this contribution, we present the results of an in-depth techno-economic analysis of some leading CCC and CCU options. Specifically, we consider CO₂ conversion to methanol, formic acid and urea (CCC) in addition to mineral carbonation of industrial wastes (CCU). We note that this work has been done in a European context, but we suggest that the results are broadly applicable. Where H₂ is required for processing, we assume that we’re using renewable H₂ via alkaline water electrolysis. We compare each of the CCC and CCU options using a range of key performance indicators (KPIs), including 2nd law efficiency, CO₂ avoided  and tonne_CO2 /tonne_Product .

The results have shown that CCU and CCC technologies are unlikely to provide a significant contribution to mitigating anthropogenic climate change. The primary bottleneck to industrial scale deployment of CCC technologies is likely to be cost effective availability of low carbon/hydrogen. Further, we find that mineral carbonation may have niche applications in the context of industrial waste remediation but the large scale deployment of this technology as a substitute for the geological sequestration of CO₂ is unlikely to be cost effective or scalable. A key determinant of the economic viability of this option will be the case-specific avoided cost associated with not having to pay for the off-site remediation of hazardous waste. Thus, we conclude that CCC and CCU technologies are only likely to be viable at  scale in the event that substantial subsidies are available to offset the high costs associated with producing renewable hydrogen and the thermodynamic cost associated with processing such a stable molecule. A potential exception to this rule is CO₂-EOR, which has proven profitable at scale (primarily in the USA), but is, in turn, highly dependent on the price at which CO₂ is available and the market price of oil.