SOCRATCES · SOlar Calcium-looping integRAtion for Thermo-Chemical Energy Storage

Lime (CaO) has been long proposed as an energy-intensive material for the storage of energy in a chemical form by means of carbonation/calcination cycles. This Calcium-looping process (CaL) is the basis of a proven pilot-scale technology for CO2 capture, which is accomplished by carbonation of CaO and its regeneration in a calciner reactor operated under high CO2 partial pressure and high temperature. The wide availability of limestone (<10€/ton) is a key factor for the feasibility of the CaL process. However, the huge potential for lime also to store energy has been inhibited by its propensity to sinter at the high temperatures of the standard CaL cycle for CO2 capture, which reduces dramatically its multicycle conversion. SOCRATCES will be built on previous R&D results of the partners indicating that the CaL process can be integrated into CSP plants for thermochemical energy storage and power generation by means of a simple closed CO2 loop. High global efficiencies (>45%) are achieved under new CaL conditions implying carbonation under high temperature (>850ºC) at high CO2 partial pressure compatible with high-efficiency power blocks. Moreover, fast calcination is carried out at temperatures < 700ºC by the Flash Calcination technology, which allows using mature and inexpensive solar receiver technology. Circulating Fluidized Bed reactors of proven efficiency. The new CSP-CaL integration yields high storage energy density (3.2 GJ/m3) with possible long-time gaps between load and discharge. SOCRATCES is aimed at demonstrating the feasibility of this integration by erecting a pilot-scale plant that uses cheap, abundant, and non-toxic materials as well as mature solar and fluidized bed reactor technologies. SOCRATCES will confer the EU a leading role in the development of efficient and non-toxic CSP with low-cost storage (<12€/kWh) and LCOE <7c€/kWh.The consortium involves the full value chain, in a well-balanced distribution between R&D groups and companies