Retrofitting strategies for improving the energy and environmental efficiency in industrial furnaces: A case study in the aluminium sector

This study aims to analyse some of the most relevant issues that the energy intensive industry needs to face in order to improve its energy and environmental performance based on innovative retrofitting strategies. To this end, a case study based on the aluminium industry, as one of the most relevant within the European energy intensive industry has been thoroughly discussed. In particular, great efforts must be addressed to reduce its environmental impact; specifically focusing on the main stages concerning the manufacturing of an aluminium billet, namely alloy production, heating, extrusion and finishing. Hence, an innovative DC (direct current) induction technology with an expected 50% energy efficiency increase is used for retrofitting conventional techniques traditionally based on natural gas and AC (alternating current) induction. A life cycle assessment was applied to analyse three different scenarios within four representative European electricity mixes. The results reported reductions up to 8% of Green House Gases emissions in every country. France presented the best-case scenario applying only DC induction; unlike Greece, which showed around 150% increment. However, the suitability of the new DC induction technology depends on the electricity mix, the technological scenario and the environmental impact indicators. Finally, environmental external costs were assessed with comparison purposes to evaluate the increase of energy and environmental efficiency in existing preheating and melting industrial furnaces currently fed with natural gas.