Energy Storage in Porous Sedimentary Rocks

  • Supervisors: Mark Wilkinson, Dimitri Mignard and Stuart Haszeldine all University of Edinburgh & Zoe Shipton University of Strathclyde 
  • Sponsor Company: ScottishPower
  • PhD student : Julien Mouli Castillo

A large proportion of renewable energy in an electricity distribution grid creates problems due to intermittency and unpredictability of supply. Consequently, unless large quantities of energy can be cheaply stored, then sufficient fossil fuel plants must be constructed to meet peak demand when renewables are not generating (and the plant owners must be paid regardless of demand) so that supply can be maintained. This is a significant issue as peak power demand in the UK is during times of winter high pressure weather, when the potential for generation from wind is very small. Such weather conditions can endure for a period of several weeks.

Air storage in man-made structures within rocks (salt caverns; mines) and man-made containers has been investigated previously by others. A relatively unexplored option for energy storage is using compressed air within porous geological formations (sedimentary rocks sometimes known as aquifers). Although small-scale borehole trials have been conducted elsewhere (Allen et al., 1984) and some theoretical calculations of storage are published (e.g. Kushnir et al., 2010), there is no assessment of the storage capacity of the UK North Sea. Given the large hydrocarbon reserves that were located there, and the large potential for CO2 storage that has been claimed, it is reasonable investigate CAES in this location.

The primary aim is to test the concept that a significant proportion of the UK’s annual electricity demand could be stored using CAES, ideally in an economical way. One challenge here might be that the energy efficiency penalty from pressure losses within the reservoir might make the economics unattractive, and a preliminary aim of the project will be to assess the magnitude and economic impact of these losses.