Waste heat usage

This paper presents an overview of heat transfer issues arising from the current national situation regarding energy sustainability and global warming. An important concern addressed is the inefficiency of present fuel usage in the UK – namely large-scale, fossil-fuelled power stations and energy-from-waste plants that discharge huge quantities of low-grade heat to the atmosphere. Other countries recover this thermal energy and use it to supply heating and hot water to nearby domestic, commercial and industrial buildings. Such district heating schemes can provide cost-effective and low-carbon energy to local populations. Although the amount of district heating in the UK is small, Sheffield currently has an award-winning city-wide district energy network that incorporates a combined-heat-and-power energy-from-waste facility, providing electricity and district heating; this scheme is explored herein, with the purpose of identifying potential expansions through heat mapping. Heat transfer will clearly need to play a major part in one or more of the various power generation technologies proposed to meet the demands of the developing energy situation – these comprise high-efficiency systems using high-temperature regenerators or high-pressure combustion and energy storage utilising supercritical steam accumulators, which are all considered in this paper. ► The UK has few district heating schemes but there is much potential for development. ► GIS mapping can identify heat sources/sinks to aid infrastructure deployment. ► Innovative CHP systems for cities need to be small-scale and high-efficiency. ► Numerical modelling of heat transfer can help optimise combustor designs. ► Energy storage can mitigate the erratic supply of non-fossil fuel energy sources.