Techno-Economic Assessment of the Need for Bulk Energy Storage in Low-Carbon Electricity Systems With a Focus on Compressed Air Storage (CAES)

Abstract

Increasing electrification of the economy while decarbonizing the electricity supply is among the most effective strategies for cutting greenhouse gas (GHG) emissions in order to abate climate change. This thesis offers insights into the role of bulk energy storage (BES) systems to cut GHG emissions from the electricity sector. Wind and solar energies can supply large volumes of low-carbon electricity. Nevertheless, large penetration of these resources poses serious reliability concerns to the grid, mainly because of their intermittency. This thesis evaluates the performance of BES systems – especially compressed air energy storage (CAES) technology – for integration of wind energy from engineering and economic aspects. Analytical thermodynamic analysis of Distributed CAES (D CAES) and Adiabatic CAES (A CAES) suggest high roundtrip storage efficiencies (~80% and 70%) compared to conventional CAES (~50%). Using hydrogen to fuel CAES plants – instead of natural gas – yields a low overall efficiency (~35%), despite its negligible GHG emissions. The techno-economic study of D CAES shows that exporting compression heat to low-temperature loads (e.g. space heating) can enhance both the economic and emissions performance of compressed air storage plants. A case study for Alberta, Canada reveals that the abatement cost of replacing a conventional CAES with D CAES plant practicing electricity arbitrage can be negative (-$40 per tCO2e, when the heat load is 50 km away from the air storage site). A green-field simulation finds that reducing the capital cost of BES – even drastically below current levels – does not substantially impact the cost of low-carbon electricity. At a 70% reduction in the GHG emissions intensity of the grid, gas turbines remain three times more cost-efficient in managing the wind variability compared to BES (in the best case and with a 15-minute resolution). Wind and solar thus, do not need to wait for availability of cheap BES systems to cost-effectively decarbonize the grid. The prospects of A CAES seem to be stronger compared to other BES systems due to its low energy-specific capital cost.