Exploring the Water-Energy-GHG NEXUS in Process Waste Heat Recovery Projects

In the last few years, the water–energy nexus concept emerged as a global issue in the international research community. However, studies on European countries are relatively few, and often focused on the energy sector and agriculture, even though industry dominates water uses in many European countries. Cooling purposes represent the main part of industrial water demand, and waste heat recovery is perceived as a main strategy to improve industrial resource efficiency. In this paper, we consider a real case study of low-temperature waste-heat recovery in a process industry and evaluate the impact of feasible interventions on primary energy and water consumption, as well as on CO2 equivalent emissions. Based on a Europe wide review of energy and water prices, of energy sources and corresponding resource efficiency indicators, a Monte Carlo model is developed to attempt a generalization of the case study to the EU-15. It is found that market factors, particularly water prices, mainly determine the economic optimum, but policy instruments, such as carbon prices, may also play a role in some countries, causing a shift towards more water intensive configurations.