Proceedings

All model pathways published by the IPCC SR15¹ require the use of negative emission technologies to limit warming to 1.5°C. It is essential that work should be undertaken to ensure that investment in this sector provides good value for money, achieves its target, and does not cause harm to the environment.

Research is currently being carried out to understand the potential for enhanced silicate weathering (EMS) as a technique for carbon capture and storage². This will likely involve the mining and application of silicate material as a fertiliser to farmland, or the construction of engineered reactor vessels using mine waste and with discharges to the environment. The goal of this technique is to increase the flux of alkalinity to the ocean, increasing the amount of carbon stored therein³.

With a better understanding of catchment alkalinity budgets it may be possible to design processes to safely maximise the amount of alkalinity we are returning to the ocean. Phosphate treatment for example requires the precipitation of Ca Phosphates under alkaline conditions. It may be possible to utilise supernatant from this process as a source of alkalinity, reducing the energy input associated with EMS.

1. IPCC. Proposed outline of the special report in 2018 on the impacts of global warming of 1 5 ° C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate cha. Ipcc – Sr15 2, 17–20 (2018).
2. Beerling, D. J. et al. Farming with crops and rocks to address global climate, food and soil security. Nat. Plants 4, (2018).
3. Renforth, P. & Henderson, G. Assessing ocean alkalinity for carbon sequestration. Rev. Geophys. 55, 636–674 (2017).