CCU: a viable weapon in the fight against climate change?

A paper published this week in Nature Climate Change assesses the efficacy of carbon capture and utilization (CCU) in mitigating climate change.

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Despite efforts to increase the use of renewable energy sources, to meet global energy demand we will need to continue to use fossil fuels for many decades. However, we also need to reverse the steady increase in the amount of CO₂ emissions caused by human activity.

In this context, Carbon Capture and Storage (CCS) technology has been recognised as a key tool in the fight against climate change. CCS works by capturing harmful CO₂ emissions produced by fossil fuels, which can then be stored in subsurface reservoirs. An alternative that is being increasingly promoted is to use CO₂ as a feedstock to produce chemicals and fuels – Carbon Capture and Utilization (CCU).

However, implementing this technology brings with it a need to identify commercial uses for the captured CO₂ that correspond to mitigation of CO₂ emissions – distinct to a short-term emissions off-set.

As such, researchers at Imperial have offered a new assessment of CCU and its potential in the context of emerging CSS projects.

Examining both the scale and rate at which CCU could be put into practice and the period for which “utilised” CO₂ is “sequestered” in the product, the paper’s authors found it to be a “negligible” player in mitigating CO₂ emissions on a meaningful scale.

Whilst acknowledging the benefits of CCU in certain contexts, the review concludes that for all markets except enhanced oil recovery (EOR), the contribution of CCU to mitigate climate change was quite marginal. This means that care needs to be taken to find options with a good all-round business case for CCU. A core conclusion is that whilst CCS can enable CCU, for reasons of scale, CCU cannot enable CCS.

The paper’s lead author Dr Niall Mac Dowell commented: “Our aim with this work was to quantify what a reasonable contribution to the fight against climate change might be from carbon capture and utilisation (CCU) relative to what is expected for carbon capture and storage (CCS).”

“It was clear when we examined the potential for all markets except enhanced oil recovery (EOR), the contribution of CCU to mitigate climate change was quite marginal meaning that care needs to be taken to find options with a good all-round business case for CCU. A core conclusion is that whilst CCS can enable CCU, for reasons of scale, CCU cannot enable CCS.”