Liquid nitrogen energy storage for air conditioning and power generation in domestic applications

The global demands for air conditioning have increased rapidly over the last few decades leading to significant power consumption and CO2 emissions. Current air conditioning systems use mechanical vapour compression systems which consume significant amount of energy particularly during peak times and use refrigerants that have global warming potential higher than that of carbon dioxide. This paper presents a new approach for providing air conditioning and power using liquid nitrogen produced from surplus electricity at off peak times or renewable energy sources. Thermodynamic analyses of different cryogenic cycles was carried out to achieve the most effective configuration that provides the required cooling and power for a 170 m2 dwelling in Libya with minimum LN2 consumption. Results showed that at today LN2 prices, it is feasible to use LN2 to provide for cooling and power demands of residential buildings with saving of up to 28% compared to conventional AC systems. However, as the LN2 price decreases to around 1.3 pence per litre, the proposed technology will have significant advantages compared to AC systems with savings of up to 79% with almost 85% of the energy stored in LN2 is recovered.