Calcium looping with inherent energy storage for decarbonisation of coal-fired power plant

Abstract

Carbon capture and storage (CCS) with energy storage (ES) systems increase flexibility and profitability of fossil-fuel-fired power systems.

Techno-economic analysis of oxy-combustion coal-fired power plant with cryogenic oxygen storage

“…Such a system can achieve high energy density and specific energy of 315.9 kWelh/m 3 and 885.2 kJ/kg, respectively ( Dm=108-180 kJ/kg [21,22]), and Li-ion batteries (DV=200-500 kWelh/m 3 ; Dm=270-720 kJ/kg [21,22]). This proves that such a system can be expected to improve flexibility and profitability of the oxy-combustion CFPP, and other CO2 capture systems such as calcium looping [18] or chemical looping combustion, by providing means that would allow utilising the daily variation in electricity price. An analysis of the thermodynamic performance for the selected cases ( Table 3) has revealed that modification of the reference air-combustion CFPP to the oxycombustion CFPP (Case 1) results in an efficiency penalty of 11.0-11.7%HHV points, depending on the operating load of the system.…”

“…Considering the variability in daily energy prices and grid demand, application of cryogenic O2 storage was found to be a feasible option to enable flexible operation of the nuclear power plant [40] and increase profitability of the air-combustion CFPP retrofitted with the calcium looping process by up to 2.3%. The latter system was shown to produce higher profits in the current economic climate than the air-combustion CFPP without CO2 capture, regardless of the efficiency penalty of 8.6%HHV points [18]. The technoeconomic feasibility of implementing peak and off-peak operation of the ASU in the oxy-combustion CFPP has been proven by Hu et al [8].…”

“…The liquid product can then be stored at a low temperature and atmospheric pressure in an insulated storage tank [8,16], which overcomes the dependence on availability of proper geological formations being the main drawback of compressed air energy storage [17]. Importantly, in the case of energy storage via cryogenic O2 storage, liquid O2 can be vaporised, and then utilised in the oxy-combustion process, unloading the ASU on demand (discharging mode) [8,18,19]. The key benefit of liquid air or O2 energy storage is high energy density of 172 kWh/m 3 [20] and 313 kWh/m 3 [18], respectively, that compare favourably with compressed air energy storage characterised with the energy density ranging between 3 and 40 kWh/m 3 [20][21][22].…”

“…Importantly, in the case of energy storage via cryogenic O2 storage, liquid O2 can be vaporised, and then utilised in the oxy-combustion process, unloading the ASU on demand (discharging mode) [8,18,19]. The key benefit of liquid air or O2 energy storage is high energy density of 172 kWh/m 3 [20] and 313 kWh/m 3 [18], respectively, that compare favourably with compressed air energy storage characterised with the energy density ranging between 3 and 40 kWh/m 3 [20][21][22]. Yet, the only challenge of this technology is the requirement for proper insulation to ensure operation in a cryogenic region.…”

“…This economic penalty can be reduced by phase CO2 capture, which assumes periodic operation in an air-combustion mode and leads to higher CO2 emissions [25,38], or implementing cryogenic O2 storage as a means of low-temperature energy storage [22] that would allow utilising variations in the daily electricity prices [18,25]. Namely, liquid O2 from the ASU can be stored during the off-peak periods of low electricity prices in order to unload the system during peak periods, which are characterised by higher electricity prices [39].…”