New approaches and best practices for closing the energy cycle within symbioses clusters

The European Horizon 2020 ULTIMATE promoted circular economy concepts within the framework of water smart industrial symbioses. It focused on industrial wastewater streams as resource for water, energy and material recovery. ULTIMATE, in nine case studies, developed and demonstrated 24 circular economy related technologies. In six out of the nine case studies, a total of ten energy-related technologies were investigated. These concerned heat recovery, storage and reuse, biogas production and valorisation, as well as a joint control system to increase the energy efficiency of two connected wastewater treatment plants (WWTPs).
Heat recovery, storage and reuse
Solutions for heat recovery, storage and reuse were developed and demonstrated in the ULTIMATE case studies in the Netherlands (Nieuw Prinsenland), United Kingdom of Great Britain and Northern Ireland (Tain) and France (Chemical Platform Roussillon).
The Dutch case study analysed the feasibility of a high temperature – aquifer thermal energy storage (HT-ATES). Excess heat from a geothermal doublet was to be stored in the HT-ATES in summer for its reuse in winter to heat greenhouses. The feasibility study showed that the concept is economically and technically feasible. For a very large greenhouse area, such as the one studied for the Dutch case study, in combination with a geothermal powerplant under construction, a 5-6% reduction in fossil fuel expenditure for the annual heat supply could be achieved. This reduction is very site specific, and in this instance was limited by the very high continuous demand for heat from the plant, which meant only a small excess capacity to supply heat to the HT-ATES was available. In case a heat source with a larger excess capacity is available, for an average sized greenhouse area, a reduction in fossil fuel demand of up to 20-30% of fossil fuel substitution could be expected.