Compressed air energy storage in porous formations: a feasibility and deliverability study

Bo Wang,Sebastian Bauer

doi:10.1144/petgeo2016-049

Abstract

Compressed air energy storage (CAES) in porous formations is considered as one option for large-scale energy storage to compensate for fluctuations from renewable energy production. To analyse the feasibility of such a CAES application and the deliverability of an underground porous formation, a hypothetical CAES scenario using an anticline structure is investigated. Two daily extraction cycles of 6 h each are assumed, complementing high solar energy production around noon. A gas turbine producing 321 MW of power with a minimum inlet pressure of 43 bar at 417 kg s−1 air is assumed. Simulation results show that using six wells the 20 m-thick storage formation with a permeability of 1000 mD can support the required 6 h continuous power output of 321 MW, even reaching 8 h maximally. For the first 30 min, maximum power output is higher, at 458 MW, continuously dropping afterwards. A sensitivity analysis shows that the number of wells required does not linearly decrease with increasing permeability of the storage formation due to well inference during air extraction. For each additional well, the continuous power output increases by 4.8 h and the maximum power output within the first 30 min by 76 MW.

Highlights

Compressed air energy storage (CAES) in porous formations is considered as one option for large-scale energy storage to compensate for fluctuations from renewable energy production
Storage options include underground storage of natural gas (e.g. Bary et al 2002), which accounts for about 20% of yearly demand in Germany in both salt cavern and porous formation storage facilities (LBEG 2015), underground storage of hydrogen produced from surplus electric power via electrolysis (Pfeiffer & Bauer 2015; Reitenbach et al 2015; Pfeiffer et al 2016, 2017), compressed air energy storage (Crotogino et al 2001) or subsurface storage of heat (Boockmeyer & Bauer 2016; Popp et al 2016)
The first study of CAES using a porous formation was conducted in Pittsfield, Illinois, USA, and showed that the concept is feasible at this site (ANR Storage Company 1990)

Summary

A CAES scenario in a porous formation

The Huntorf power plant is the first commercial CAES facility in the world; it started operating in 1978 and produces 321 MW power of electrical energy maximally for 3 h since an upgrade in 2006 (E.ON SE 2016). The injection and extraction rates specified can be supported by the formation if six wells are used This indicates that the porous formation simulated can support the cyclic operation of the Huntorf gas turbine, and can sustain a continuous power output of 321 MW for 6 h at an extraction air mass flow rate of 417 kg s−1, corresponding to 1926 MWh of electrical energy production. An estimation of the maximum possible instantaneous power output was performed by only maintaining the well BHP (Fig. 5b, ‘Fixed BHP’ line) and allowing higher flow rates at the wells This corresponds to the case where a maximum amount of air is extracted at each point in time and instantaneous power is high. Together with the deliverability analysis, this allows a rough design of the CAES storage set-up to be made

Findings

Discussion

Summary and outlook