Review and Techno-Economic Analysis of Emerging Thermo-Mechanical Energy Storage Technologies

Abstract

Thermo-mechanical energy storage can be a cost-effective solution to provide flexibility and balance highly renewable energy systems. Here, we present a concise review of emerging thermo-mechanical energy storage solutions focusing on their commercial development. Under a unified framework, we review technologies that have proven to work conceptually through project demonstration at a scale above 1 MW by describing the current state of commercial development, quantifying techno-economic parameters, outlining the challenges, and assessing each technology’s potential for commercial viability. The levelized cost of storage for thermo-mechanical energy storage at storage duration between 8 h and 1 week is cheaper than that of lithium-ion batteries and hydrogen storage; however, energy storage for such duration does not pay for itself at the current renewable penetration levels. For medium-term energy storage to be viable, at the realistic storage cost of 15 USD/kWh to 40 USD/kWh, the investment cost for power components should decrease to one-fifth of the current costs. Thermo-mechanical energy storage can be economically viable at the current investment costs in off-grid systems only when the marginal cost of alternative fuel exceeds 100 USD/MWh. We identified the cost ratio (charge power cost/discharge power cost) and the discharge efficiency as the critical technology-related performance parameters. Other external factors such as wind and solar fractions, demand, interconnections, sector coupling, and market structure play an important role in determining the economic feasibility of thermo-mechanical energy storage.

Investment-based optimisation of energy storage design parameters in a grid-connected hybrid renewable energy system

“…Both tanks store thermal energy in solid material such as volcanic rocks. The stored thermal energy is extracted through a Brayton cycle when electricity is needed [17,18].…”

“…An MSES system utilises electric heaters to converts electrical energy to thermal energy that is stored in tanks of molten salt. Unlike TES and PTES sytems, an MSES system produces electricity by discharging the stored thermal energy through a Rankine cycle [18]. In an aCAES system, electrical energy is utilised to compress air to high-pressure during the charging the process.…”

“…StorageX parameters[11,18,20].Discharge capacity 17.28 13.08 20.80 12.58 10 3 €/MW fixed cost (f d )…”

Part-Load Energy Performance Assessment of a Pumped Thermal Energy Storage System for an Energy Community

“…It essentially combines thermal and mechanical energy storage components with other components, including heat exchangers, turbines, and compressors [14]. In agreement with [14,15], TMES has fundamentally four sub-categories, based on their operation principles: thermal energy storage (TES), compressed-air energy storage (CAES), liquid-air energy storage (LAES), and pumped thermal energy storage (PTES). Each sub-category is divided into different systems, which are based on the combination of components within them.…”

“…In a literature review about CBs, Dumont et al [22] described innovative technologies, analyzed the involved market, and examined existing prototypes. Then, similarly to [15], PTES is subdivided into Brayton and Rankine types. One of their main conclusions is also the absence of studies analyzing the part-load of CBs, which could be extremely helpful in order to assess the performance deterioration in part-load operation.…”