Increasing fossil power plant flexibility by integrating molten-salt thermal storage

• Published in: Energy (Oxford) Vol. 118; pp. 876 - 883
• Main Authors: Garbrecht, Oliver, Bieber, Malte, Kneer, Reinhold
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2017; Elsevier BV
• Subjects: case studies; Computer simulation; Control reserve; electric power; Electric power plants; Electricity distribution; Energy storage; Exergy; Fluctuations; Fossil fuels; Fossil power plant; Grid stability; Heat; Heat exchangers; Heat transfer; Incinerators; Increased flexibility; Lignite; markets; Molten salt thermal storage; Numerical analysis; Power plants; Primary reserve; Renewable energy sources; steam; Steam electric power generation; Storage systems; Studies; Thermal storage; Control reserve; Primary reserve; Molten salt thermal storage; Grid stability; Fossil power plant; Increased flexibility
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2016.10.108

Increasing market penetration of renewable energy sources requires measures to stabilize the electric grid. This includes reducing generator output fluctuations as well as providing control reserve. The present study investigates the use of molten-salt storage systems in fossil-fired power plants by conducting a series of numerical process simulations. Two case studies are performed: First, an incinerator representing a heat-controlled facility with fluctuating output due to varying customer steam demand. Second, a small-size lignite-fired power plant for providing control reserve, representing a power-controlled facility. The results show that the concept allows significant attenuation of fluctuations in the heat-controlled facility. For a broad range of customer steam extraction, a steady production of electrical energy could be obtained without substantial modifications to the plant. Positive and negative control reserve in the power-controlled facility can be provided through the use of a storage system with relatively low exergetic losses. However, a number of additional heat exchangers and significant modifications to the steam cycle are required. •The implementation of molten-salt thermal storage systems in fossil power plants is presented.•Thermal performance of the storage systems has been investigated by conducting process simulations.•Two different power plant types are the subject of this study: heat controlled and power controlled.•Results indicate that thermal storage systems are suitable to increase power plant flexibility.