Cameron Hepburn, Ella Adlen, John Beddington, Emily A. Carter, Sabine Fuss, Niall Mac Dowell, Jan C. Minx, Pete Smith & Charlotte K. Williams
Carbon dioxide utilisation – making valuable products from CO2 – is a potential way to lower the net costs of reducing emissions or of removing carbon dioxide from the atmosphere. We review the economic and technological prospects of ten such pathways to assess scale and cost prospects in 2050. Using CO2 in chemicals, fuels, and via microalgae to make products, comprise ‘cycling’ pathways: they might reduce carbon dioxide emissions by displacing fossil fuel derived CO2 but they have limited potential for carbon dioxide removal. Some CO2 chemicals, such as CO2 based polymers, are profitable in the present day, but CO2 based fuels are high up on the cost curve. ‘Closed’ pathways such as those involving construction materials can both utilise and remove carbon dioxide for the long term. They might be low cost, and the end-markets are large, but they have high regulatory barriers to scale. Land-based CO2 utilisation pathways such as soil carbon sequestration, afforestation/reforestation and biochar can increase agricultural output and remove carbon dioxide. They can be characterised as ‘open’ pathways wherein the CO2 can return to the atmosphere easily, and they are relatively low cost. Using a process of structured estimation and an expert opinion survey, our assessment suggests that each of the ten pathways could scale to over 0.5 Gt carbon dioxide utilisation annually, although barriers remain substantial and resource constraints prevent the simultaneous deployment of all pathways. Uncertainty over scaling means that there is a wide range of potential outcomes for 2050. Notwithstanding the many caveats, the potential scale of utilisation could be considerable. Much of this potential CO2 utilisation – notably in ‘closed’ and ‘open’ pathways – may be economically viable without dramatic shifts in prices. The specific assumptions of the low scenario imply an upper bound of over 1.5 Gt CO2 yr-1 at well under $100/t CO2u. For policymakers interested in climate change, these figures demonstrate the theoretical potential for correctly designed policies to incentivise the displacement of fossil fuels or the removal of CO2 from the atmosphere.