Reducing the long-term greenhouse gas (GHG) emissions of the industrial sector is one of the most challenging aspects of the energy transition. The combination of Concentrating Solar Heat (CSH) and Thermal Energy Storage (TES) technologies can provide a real solution to achieve carbon neutrality.
Due to the discontinuous nature of the available solar source, the complete substitution of fossil fuels with renewable solar sources would currently require very high investment costs for the oversizing of the solar field and the attached storage system, in particular, if combined with a continuous industrial process working under stationary conditions. This paper presents the benefits that can arise from the hybridization of a CSH plant with an additional renewable source: the biogas generated by the anaerobic digestion of biomasses. The application study involves the supply of high-temperature heat, 15 MWth at 560°C, to an industrial user through a CSH +TES plant with linear parabolic trough collectors, hybridised with a biogas boiler and fossil source backup for the supply of constant and continuous thermal power 24/7. In this paper, the pre-feasibility study of the application has been analysed from both technical and economic point of view, estimating the cost of the heat produced (LCOH - Levelized Cost of Heat). The results show that it is possible to reduce the carbon footprint (85 vs 221 kgCO2/MWhth) of a high-temperature industrial process in the hard-to-abate sector in an economical sustainable way thanks to the use of a suitable mix of renewable energies. Based on the assumptions made, the CSH hybridized configuration with biogas boiler and digester has a lower LCOH (44-59 €/MWh) than a natural gas-only heat supply solution (49-85 €/MWh) both for a minimum and maximum cost scenario.
