Alves, Jorge MaiaSilva, João Paulo Mendes da2025-02-182025-02-182024-04-032023-09-01http://hdl.handle.net/10400.5/98525The thermodynamics associated with compressed air energy storage is discussed. A systematic methodology for technology analysis, according to compression and reservoir characteristics, is proposed. The technologies and prototypes presented in the literature are organized accordingly, and the potential energy/power densities, and heat losses calculated. The first sensitivity analysis of hydro-pneumatic levelized cost of electricity storage for a set of twelve power system applications, ranging from primary response to seasonal storage is done, using as parameters the specific power and energy investment costs and round-trip efficiency. The electric-to-electric round-trip efficiency for hydro-pneumatic energy storage systems is discussed, using a lab-scale hydro-pneumatic energy storage system that was built using commercially available bladder hydraulic accumulators. In general, the results show that hydro-pneumatic energy storage can be very competitive whenever the number of annual cycles is sufficiently high, as happens in the case of primary response application but, even for applications with a low number of annual cycles, it can be competitive for applications with a high ratio power/capacity. A comparison with the dominant technologies, pumped hydro and Li-Ion, shows that, for the highest hydro-pneumatic energy storage investment costs considered, this technology will only be competitive for primary response, but, for the lowest investment costs considered, hydro-pneumatic energy storage is more cost-effective than Li-Ion for all applications, and can even be more cost-effective than pumped hydro in four of the twelve applications. The main challenges to the development of hydro-pneumatic energy storage systems are discussed, and solutions to these challenges are proposed in the form of two submitted patents.engEnergy storageHydro-pneumatic energy storageLCOSArmazenamento de energiaArmazenamento de energia hidropneumáticodoctoral thesis101548958