Reef2 Water – New pathways for exploiting the untapped energy potential of wastewater in Europe

In the wake of the “Energiewende”, growing attention is turned towards the yet untapped energy saving potential of the wastewater sector. Wastewater treatment plants are large consumers of energy and are often key contributors to the carbon footprint of municipalities and city governments. Their energy consumption usually accounts for the bulk of operational costs of wastewater utilities, sometimes up to 60 per cent. However, despite being a huge source of electricity and heat, sewage is often overlooked. In fact, the energy it contains can be 10 times bigger than what is needed to treat it. In recent decades, an increasing number of wastewater utilities have deployed energy efficiency measures and novel technologies to better exploit the energy in wastewater. Evaluations of pioneering projects show that utilities are not only capable of becoming energy self-sufficient, but also suppliers of energy thereby diversifying the local mix.

The project Reef2 Water recognized that sewage is at the heart ofthe water-energy nexus. Its main goal was to drive up energy efficiency and renewable energy production of wastewater treatment plants. It took an innovative approach in integrating solid waste and wastewater streams and infrastructures. Where applicable, bio-waste was used to enrich sewage sludge, helping to elevate outputs of heat and electricity in a process called co-fermentation. To prove that the new technologies can be technically feasible and make economic sense, project partners developed an extensive assessment tool in close collaboration with utility operators in­ a series of workshops. Another key task of Reef2 Water was to understand the legal and policy framework and to advocate for policy alternatives that boost wide-scale use of wastewater-to-energy solutions.

The project was funded by the European Development Bank’s Interreg Central Europe Programme and was carried out through 11 research institutes and wastewater utilities from Italy, Czech Republic, Germany, Croatia, and Austria. adelphi coordinated one of the four main work packages, which sought to create an environment enabling the future uptake of Reef2 Water solutions. Drawing on one of its key competencies in the field of water resources, its team led an analysis of relevant legislation and policies in each of the five countries, as well as at the European level. Key barriers impeding further implementation and dissemination of Reef2Water solutions were identified, and policy recommendations supportive of an energy-efficient wastewater sector developed. In parallel, “Regional Strategies” were designed in collaboration with local municipalities and policy-makers, which outline concrete steps for implementing the Reef2 Water approaches beyond the project’s end.