Low grade thermal energy sources and uses from the process industry in the UK

• Published in: Applied energy 2012-01, Vol.89 (1), p.3-20
• Main Authors: Ammar, Yasmine, Joyce, Sharon, Norman, Rosemary, Wang, Yaodong, Roskilly, Anthony P.
• Format: Article
• Language: English
• Subjects: Applied sciences; cooling; decision making; Economics; electricity; Energy; Energy efficiency; energy recovery; Exact sciences and technology; Greenhouse gas emission reduction; heat; Heat recovery; Heat recovery technology; Heat sources; Incentives; industry; issues and policy; Low grade heat source; Policies; Process industry; Quality; Streams; temperature; Thermal energy; Thermal energy management; viability
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2011.06.003

► Drivers for heat recovery studies are reviewed in the process industries. ► Waste heat recovery potential can be assessed by the exergy efficiency of the heat transfer to a suitable sink. ► The purpose of low grade heat recovery is to reduce the production of entropy in the environment. ► Potential uses for low grade heat and recovery technologies are established by foreseeing future societal needs. ► The evidence suggests that stronger government policy and regulation incentives can facilitate low grade heat recovery. Thermal energy loss in the process industry is a significant issue due to the high temperatures and multiple heat intensive processes involved. High-grade thermal energy is typically recovered within processes. However, lower grade heat is often rejected to the environment. The benefits of capturing and utilising low grade thermal energy are highly dependent on the qualities and properties of the heat in the waste streams. The temperature of the low grade heat stream is the most important parameter, as the effective use of the residual heat or the efficiency of energy recovery from the low grade heat sources will mainly depend on the temperature difference between the source and a suitable sink, e.g. another process or space heating/cooling. In general, the temperatures of these waste heat sources are too low to produce electricity and direct heat use will depend on whether potential user can be found. This paper presents past and current drivers for heat recovery studies. High and low grade heat sources are defined according to the viability of recovery within the processes. Firstly, high grade heat capture within the processes is reviewed. Then, the focus is on the potential for low grade heat capture outside of the original plant. The paper addresses the potential for low grade heat recovery with regard to new incentives and technological advances. Finally, different aspects which influence the decision making for low grade heat recovery in the process industry are discussed. It is concluded that organisational, financial and economic barriers might be overcome and benefits from a holistic vision could be gained with stronger governmental policy and regulation incentives.