Optimisation and feasibility of a pumped thermal electricity storage system using transcritical carbon dioxide

Abstract

Among all the possible sources of electricity, only nuclear and renewable sources are not criticized out of global warming concerns. However, they both present non-negligible drawbacks: safety and waste-fuel related issues for the first ones and their inherently random and variable nature for the second ones. Therefore, storing electricity has become a major priority nowadays as it reduces the amount of electricity produced while enabling to use electricity whenever it is needed to match the greed requirements. This concept of electricity storage can be applied for nuclear power plants and renewable sources, or both of them coupled. As the two main large-scale electricity storage technologies, i.e. PHES and CAES, suffer from serious drawbacks, new technologies are needed. Among others, a new storage system where transcritical carbon dioxide flows to store electricity as sensible heat was introduced in 2012. In the present work, this system is first optimized based on an exergo-economic method before its competitiveness and feasibility are discussed. Finally, a few practical considerations about the applicability of this technology are proposed.