Chapter 5 - Geology and the Reduction of Emissions

Abstract

As well as being fundamental to the long-term carbon cycle, energy, and climate change, rocks also provide ways in which climate change can be reduced or mitigated. Layers of sedimentary rocks provide deep potential repositories for carbon dioxide and through the technology of carbon capture and storage (CCS), the long-term carbon cycle can essentially be speeded up to permanently remove industrial CO2—associated with power stations and industry—from the atmosphere. Though great strides are being made to decarbonise power generation through the uptake of renewables, there are still few decarbonisation routes for cement and ammonia factories, or refineries. The parts of CCS—CO2 capture, pipeline transport and geological burial—have been demonstrated separately, but never together on a large scale, in other words at a scale that would make a difference in climate-change terms. A variant on CCS, bioenergy and carbon capture and storage (BECCS), is attractive to politicians and policymakers alike because it offers ‘net negative’ emissions, though its viability in the face of the required agricultural resources to make it work as an effective large-scale abatement technology is in doubt. More indirect ways that geological materials and resources can reduce emissions or mitigate climate change are through geothermal energy, storage of excess renewables energy in geological compressed air energy storage (CAES), and geological storage of hydrogen as part of the low-carbon hydrogen economy. Geological materials will likely provide many of the key elements for grid-scale battery storage, and for batteries for electric vehicles. Not to be forgotten is the likely global role that deep geological repositories will play in the safe long-term disposal of waste from low-carbon nuclear power stations.