Technical and economic assessment of ORC and cogeneration including a combined variant – A case study for the Polish automotive fastener industry company

Abstract

The global increase in electricity prices seen in recent years contributes to the development of combined heat and power (CHP), which is easily becoming an available technology to improve energy efficiency in manufacturing plants, with a simple payback time of the investment becoming more beneficial. The technological process of simultaneous generation of electricity and useable heat, due to lower fuel consumption, gives great economic savings and is environmentally favorable. In Poland, this solution has a significant impact on CO2 reduction, due to the high emission factor of electricity generation resulting from production based mainly on coal. The reduction of CO2 emissions with a simultaneous increase in energy efficiency is reflected in a reduction of production costs, which makes the plant investing in such a solution more competitive in the market. Unfortunately, the companies are not always aware, and able to utilize the full heat potential outcoming as a by-product during electricity generation when generating electricity e.g., in a cogenerator. For this reason, the combination of cogeneration with Organic Rankine Cycle (ORC) technology becomes a promising way to fully utilize waste heat from a cogenerator. In this article, techno-economic analysis of various cogeneration and ORC variants carried out in an industrial plant producing fasteners for the automotive industry is presented and discussed. The analysis also covers the combined variant of cogeneration with ORC. The analysis shows that the continuous increase of electricity prices justifies investment in cogeneration in contrast to the ORC engine, which is characterized by high investment costs and low efficiency, nevertheless, in combination with cogeneration may become more affordable for industrial plants with energy-intensive processes such as heat treatment.