Increasing energy demand for water systems, increasing energy prices, advancement towards green energy and greenhouse gas (GHG) emissions mitigation goals, and the impacts of climate change are all driving Distributed energy resources (DER). Self-generation of energy may reduce costs, improve system resilience and reliability, and reduce GHG emissions. Renewable forms of DER available to utilities can include organic matter in wastewater, hydropower, thermal heat in wastewater, waste heat from converting gas to electricity, solar, and wind. Drawing on all these forms of energy, wastewater treatment plants can potentially generate far more energy than their sites require. As utilities can store energy (e.g., as gas or water at elevation), and can often shift their own energy demands through time, they are an important potential element of a more renewables-based future grid. However, implementation challenges can be significant, and overall costs versus benefits depend on site-specific factors, including physical conditions such as available space and technology, policy, and regulations.

This report provides guidance for utilities, related stakeholders and policy makers interested in pursuing DER. It creates a practical resource by drawing on experiences including success and risk factors. The main focus of this report is on energy generation, but other elements of DER resource integration (energy storage, demand response, and micro-grids) are touched upon.