Power-to-Process-Heat in Industrial Combined Heat and Power Plants – Integration of a Large-Scale Thermochemical Energy Storage

Abstract

With an increasing share of electricity from renewable energy sources in the German energy market, storage systems are needed to close the gap between production and demand. The thermochemical storage system based on the reversible reaction of CaO and Ca(OH)2 is one of the most promising approaches for high temperature thermal energy storage concepts. In this paper, a concept is developed to integrate a largescale thermochemical storage system into an industrial heat and power plant. A mixed integer linear problem was created in TOP-Energy to conduct economical optimizations of the industrial heat and power plant with and without storage system. The linearization of the storage system was achieved by a correlation of input and output streams of a stationary CSTR MATLAB model. Hourly simulations for the years 2019, 2030 and 2040 with the help of energy price prognoses proved the economic benefit of the operation with storage system. Keywords-thermochemical energy storage, industrial heat and power plant, CaO/Ca(OH)2, fluidized bed reactor, mixed integer linear programming.

The Potential of Thermal Energy Storage for Sustainable Energy Supply at Chemical Sites

“…The key premises are as follows: (1) ongoing deployment of PV and wind power to ensure, inter alia, that electricity supply and consumption become carbon neutral before 2050 in accordance with the German Renewables Energy Act [19]; (2) nuclear phase-out by 2023 and coal phase-out by 2032; (3) continuous addition of green gases to the gas mix, switch to green hydrogen (0 t-CO 2 /MWh) completed in 2045; (4) prices for CO 2 emission allowance increase according to the Sustainable Development Scenario of the World Energy Outlook 2020 [20]; (5) increased efficiency and refurbishment measures will reduce the overall heating demand by 25% until 2050, future heating demand will be covered through green gases as well as environmental (e.g. solar thermal), electric and district heating; (6) the increased use of electric vehicles reduces the energy demand in the transport sector by 50% until 2050, demand is divided approximately 50/50 between electric vehicles and synthetic fuels by the year 2050; (7) the required flexibilities are provided by pumped storage power plants, battery storage, electrolysers, load shedding and demand flexibility through e-mobility and the heating sector (heat pumps). In the enervis market model, the three sectors electricity, heating and transport are modelled together with the transmission capacities to other countries.…”

“…Klasing et al provide an overview of the first four technologies and discuss readiness levels, advantages, and disadvantages [6]. The application of an electrically charged TCS system based on the reversable reaction of calcium oxide (CaO) and calcium hydroxide (Ca(OH) 2 ) was investigated by Backofen et al [7,8]. The storage system, consisting of two silos and two fluidized bed reactors [9], was integrated into an industrial heat and power plant model.…”

“…In general, the potential of TES in cogeneration plants as a flexibility option has been recognized. However, with the exception of Backofen et al [7,8], the aforementioned ETES-CHP concept has not been the focus of scientific studies. For this reason, the present paper elaborates on the application of the ETES-CHP concept with molten salt storage in utility infrastructures of large chemical sites.…”