A liquid air energy storage system, comprising: an air liquefier comprising: an air input having compression means configured to compress input air and cooling means configured to cool the input air; an adsorption air purification unit coupled to the air input and configured to purify the compressed and cooled input air from the air input; and a cold box coupled to the adsorption air purification unit and configured to liquefy the purified air from the adsorption air purification unit; a liquid air storage facility for storing the liquefied air from the air liquefier; a power recovery unit coupled to the liquid air storage facility comprising: a pump configured to pressurize the liquefied air from the liquid air storage facility into a high-pressure liquefied air; an evaporator configured to transform the high-pressure liquefied air from the pump into high-pressure gaseous air; an expansion turbine (161, 162, 163, 164) coupled to the evaporator and capable of being driven by the high-pressure gaseous air from the evaporator; a generator coupled to the expansion turbine and configured to generate electricity from the expansion turbine; an exhaust coupled to the expansion turbine for exhausting low-pressure gaseous air from the expansion turbine to an air output; wherein the exhaust is coupled to the adsorption air purification unit such that at least a portion of the low-pressure gaseous air exhausted from the expansion turbine is usable to regenerate the adsorption air purification unit; a heat exchanger; and a first fluid pathway passing from the exhaust of the expansion turbine through the heat exchanger to the input of the adsorption air purification unit; characterised by a second fluid pathway passing from the output of the evaporator through the heat exchanger to the input of the expansion turbine; wherein the heat exchanger is configured to permit the exhausted air from the expansion turbine to be cooled by the high-pressure gaseous air from the evaporator before passing the exhausted air to the adsorption air purification unit. an air liquefier comprising: an air input having compression means configured to compress input air and cooling means configured to cool the input air; an adsorption air purification unit coupled to the air input and configured to purify the compressed and cooled input air from the air input; and a cold box coupled to the adsorption air purification unit and configured to liquefy the purified air from the adsorption air purification unit; an air input having compression means configured to compress input air and cooling means configured to cool the input air; an adsorption air purification unit coupled to the air input and configured to purify the compressed and cooled input air from the air input; and a cold box coupled to the adsorption air purification unit and configured to liquefy the purified air from the adsorption air purification unit; a liquid air storage facility for storing the liquefied air from the air liquefier; a power recovery unit coupled to the liquid air storage facility comprising: a pump configured to pressurize the liquefied air from the liquid air storage facility into a high-pressure liquefied air; an evaporator configured to transform the high-pressure liquefied air from the pump into high-pressure gaseous air; an expansion turbine (161, 162, 163, 164) coupled to the evaporator and capable of being driven by the high-pressure gaseous air from the evaporator; a generator coupled to the expansion turbine and configured to generate electricity from the expansion turbine; an exhaust coupled to the expansion turbine for exhausting low-pressure gaseous air from the expansion turbine to an air output; wherein a pump configured to pressurize the liquefied air from the liquid air storage facility into a high-pressure liquefied air; an evaporator configured to transform the high-pressure liquefied air from the pump into high-pressure gaseous air; an expansion turbine (161, 162, 163, 164) coupled to the evaporator and capable of being driven by the high-pressure gaseous air from the evaporator; a generator coupled to the expansion turbine and configured to generate electricity from the expansion turbine; an exhaust coupled to the expansion turbine for exhausting low-pressure gaseous air from the expansion turbine to an air output; wherein the exhaust is coupled to the adsorption air purification unit such that at least a portion of the low-pressure gaseous air exhausted from the expansion turbine is usable to regenerate the adsorption air purification unit; a heat exchanger; and a first fluid pathway passing from the exhaust of the expansion turbine through the heat exchanger to the input of the adsorption air purification unit; characterised by a second fluid pathway passing from the output of the evaporator through the heat exchanger to the input of the expansion turbine; wherein the heat exchanger is configured to permit the exhausted air from the expansion turbine to be cooled by the high-pressure gaseous air from the evaporator before passing the exhausted air to the adsorption air purification unit. a heat exchanger; and a first fluid pathway passing from the exhaust of the expansion turbine through the heat exchanger to the input of the adsorption air purification unit; characterised by a second fluid pathway passing from the output of the evaporator through the heat exchanger to the input of the expansion turbine; wherein the heat exchanger is configured to permit the exhausted air from the expansion turbine to be cooled by the high-pressure gaseous air from the evaporator before passing the exhausted air to the adsorption air purification unit.