Electricity generation from low-temperature industrial excess heat—an opportunity for the steel industry

Abstract

Awareness of climate change and the threat of rising energy prices have resulted in increased attention being paid to energy issues, and industry seeing a cost benefit in using more energyefficient production processes. One energy-efficient measure is the recovery of industrial excess heat. However, this option has not been fully investigated and some of the technologies for recovery of excess heat are not yet commercially available. This paper proposes three technologies for the generation of electricity from low temperature industrial excess heat. The technologies are thermoelectric generation, organic Rankine cycle and phase change material engine system. The technologies are evaluated in relation to each other, with regard to temperature range of the heat source, conversion efficiency, capacity and economy.Because the technologies use heat of different temperature ranges, there is potential for concurrent implementation of two or more of these technologies. Even if the conversion efficiency of a technology is low, it could be worthwhile to utilise if there is no other use for the excess heat.The iron and steel industry is energy intensive and its production processes are often conducted at high temperatures. As a consequence large amounts of excess heat are generated. The potential electricity production from low temperature excess heat at a steel plant was calculated together with the corresponding reduction in global CO 2 emissions.

Energy efficiency through industrial excess heat recovery—policy impacts

“…the heat production technology in the DH system. (Broberg Viklund and Johansson 2014) Johansson and Söderström (2013) studies electricity generation from low-temperature industrial excess heat within the steel industry, showing reduced CO2 emissions.…”

Dynamic model of supercritical Organic Rankine Cycle waste heat recovery system for internal combustion engine

“…The WHR system converts the exhaust or coolant heat into either mechanical rotation or electrical power, which increases the thermal efficiency and, as a result, reduces the fuel consumption of the engine (Glover et al, 2014;Imran et al, 2015). Within the WHR system, three technologies were considered: Thermoelectric Generator (TEG), Organic Rankine Cycle (ORC) and Phase Change Material (PCM) engine system; these can be found in the literature (Johansson and Söderström, 2014). The selection of appropriate technology for the WHR is dependent on the type of heat source, the heat transfer requirement, and the application, etc.…”

“…The selection of appropriate technology for the WHR is dependent on the type of heat source, the heat transfer requirement, and the application, etc. The conversion efficiency of the PCM, TEG and ORC are, generally, up to 2.5%, 5% and 16%, respectively (Johansson and Söderström, 2014). Among these methods, the ORC is well established and preferred for waste heat recovery from low and medium grade heat sources because of its high thermal efficiency, low weight, small volume, simplicity, availability of components and compatibility with a range of heat sources (Gao et al, 2012;Shu et al, 2014;Johansson and Söderström, 2014).…”

Industrial excess heat use: Systems analysis and CO2 emissions reduction

“…[7] A number of district heating (DH) systems in Sweden accept industrial excess heat as a part of their fuel mix and in 2011 excess heat accounted for 7.2% of the heat deliveries in the Swedish DH networks [8; 9]. Several research studies investigate excess heat recovery (both thermal applications and heat driven electricity generation) and heat storage technologies [10][11][12][13][14][15][16][17][18]. Johansson and Söderström [13] compare and evaluate heat driven electricity generation technologies for recovery of low-temperature industrial excess heat based on heat source temperature, efficiency, capacity, economy and potential electricity production.…”

“…The study indicates that investments in heat driven electricity generation technologies could be profitable, however not all associated costs are included in the study. [13] Campana et al [11] estimates the potential power output from excess heat driven Organic Rankine cycle (ORC) in the cement, steel, glass and oil and gas industry in 27 European countries. The authors conclude ORC to be a viable option for heat recovery and estimate the potential electricity generation from ORC to approximately 21.6 TWh per year.…”