Why is this research needed?

Secure storage of CO₂ in porous rocks is widely believed to be available for huge tonnages of CO₂, equivalent to hundreds of years of emissions from industrial nations. However this is very different to the certainty required for commercial investment to develop a storage site.

What is this research investigating?

This project will use a proven classification method of subsurface resources, recognised and used worldwide, which is based on a United Nations system, and has been adapted for CO₂ storage by SPE, the Society of Petroleum Engineers. That takes into account the extent and certainty of geological information available, the availability of engineered connections such as pipeline, and the amount of interest in commercial takeup.

These site specific bottom-up evaluations will be built using storage databases available for offshore of the UK (CO₂ stored), and for Norway (NPD), and the onshore of the USA (NETL Atlas; Dual Challenge NPC). Those tonnages of storage will be compared with the top-down policy requirements of nations pledging to use CCS as an essential tool in their emissions reduction or NetZero ambitions to 2050. Outline scoping work suggests that we will find a very significant shortfall in bottom-up capacity to be delivered. That means that government policy to require action needs to be immediate, to increase commercial quality storage available to the EU – which needs to progress in a cumulative 100 MtCO₂ in 2030, 3 GtCO₂ in 2050, and 6 GtCO₂ in 2060.

This research will also evaluate physical constraints on very large tonnages of injected CO₂ fluids. One of these is pore pressure buildup, which can fracture the reservoir and seal unless injection is halted. Seepage and dispersal of pore pressure is controlled by the flow through enclosing seal rocks above, sideways and below. The researchers will search the storage databases to make a numerical evaluation of surrounding seal – too much flow produces leakage, too little flow causes pressure buildup, and the mid-range seepage flow can be simulated to understand the permitted rates of injection. The research will seek a natural analogue for massive injection of fluids into the deep subsurface. That is the disposal of waste flowback water from fracking, injected into deep underground saline aquifers in Oklahoma, USA. That is very similar to projections in the North Sea, at rates of 42-126 million tonnes CO₂ per year. Understanding these environmental consequences will assist in designing secure and resilient CO₂ storage at national or North Sea size scale.

What does the research hope to achieve?

For Net Zero, additional and significant actions will now be required on storage capacity from all actors. A narrative compilation will be produced, estimating the bottom-up effort required to make ready storage gigatonnes for the UK, and North Sea as predicted by bottom-up modellers, and compared to the top-down policy-pull requirements.