Water treatment plants powering forward with microgrids

Clean energy microgrids and battery energy storage systems (BESS) are vital energy solutions as wastewater treatment system operators aim to boost resiliency, decarbonize operations, reduce costs and enhance water supply security. Associate vice president for energy, Mushtaq Ahmad, and microgrid power systems lead, Abinet Eseye, share how water treatment plants are powering forward with microgrids.

Once considered beyond the reach of many wastewater treatment plant operators, microgrids are now regularly sought out for their anticipated macro benefits, from protecting against disruptive power outages to extending on-site energy production that reduces local emissions and boosts water reuse efforts.

For officials in Rialto, a city of 100,000 people east of Los Angeles in the United States (U.S.), integrating a microgrid into wastewater treatment plant upgrades is expected to improve resiliency, power facility loads with onsite renewable energy to reduce utility costs and feed excess renewable energy into the public grid.

More cities are evaluating microgrids and distributed energy resources (DERs) for their water utilities in locations facing rising operational risks posed by extreme climate events such as wildfires, more frequent and powerful hurricanes and snowstorms.

Boosting reliability and clean energy management

In Rialto, the city’s interest in pursuing a first-of-its-kind microgrid for wastewater treatment began with concerns about potential environmental damage from discharges posed by a lengthy disruption at the facility. Beyond resiliency, the wider carbon emissions benefits of a biogas-powered microgrid supported by solar and battery storage made sense for the city, which prioritizes environmental stewardship.

The design includes a biogas-fueled 360 kW reciprocating engine, a 1.6 MW solar photovoltaic (PV) system and a 2.5 MWh lithium Battery Energy Storage System (BESS). The generating units would provide all the facility’s energy needs, with the microgrid ensuring seamless operations in the event of a power outage.

Tax credits, available federal aid and grants, efficiency gains and the potential sale of extra energy combine to advance the estimated $26 million project on a cost-neutral basis—a critical need in easing any ratepayer burdens.

The cost of a PV system with a BESS unit could be recovered in less than eight years, helping to save $1 million in plant operating costs over 15 years. Once built, the Rialto plant system is expected to reduce CO2 emissions from treatment by about 600 million metric tons annually.

Initial investments can seem daunting. However, our teams have shown that with a long-term view and a clear understanding of potential benefits, microgrids are no longer out of reach, given the real challenges many commercial and industrial sectors and government agencies are facing.

“Our teams have the knowledge, skills and technology to analyze, design and construct microgrids that are not only the best in the world, but are the best for the world.” —   Abinet Eseye, microgrid power systems lead, energy

State of play

The biggest expense for wastewater treatment systems is energy — making up anywhere between 30 percent to 40 percent of costs.

Microgrids — which can work with or independently from public electricity grids — should be pursued as part of a full energy-use strategy as systems scale to meet future demands in water supply. This includes supplementing clean, on-site power generation for more energy-intensive purification applications.

In California, where endless cycles of drought have stretched supplies, the state has promulgated direct potable reuse (DPR) regulations that would allow purified recycled water to be placed directly into a public water system, rather than released into the ocean.

Improving resilience and meeting future needs are important considerations for microgrids. Whatever the benefits, the goal should be to reduce baseline energy use across the entire operation to allow investment to be cost-neutral.