Q&A: Microgrids in water conveyance applications

May 22, 2023
A Q&A interview about microgrid systems with Greta Foster following Eaton’s microgrid project for the Tussing Water Booster Station in Columbus, Ohio.

In February 2023, Eaton won a contract to help utility AEP Ohio establish Columbus, Ohio’s first renewable energy microgrid at the Tussing Water Booster Station.

WaterWorld had the opportunity to speak with Greta Foster, product line manager for microgrids and distributed energy resources as Eaton, to discuss microgrid systems and the now-complete Ohio microgrid project.

Q: How do microgrid systems help support clean water infrastructure?

A: With the rise of extreme weather events and an aging centralized electric grid, extended power outages are a growing threat to the resilience of water infrastructure in our communities. At the same time, ambitious sustainability commitments and rising energy costs are creating pressure for many water departments to decarbonize their operations and use electricity more wisely.

Microgrids are providing a proven solution to these challenges — delivering affordable and sustainable energy along with the ability to keep the power on and operate critical assets during a grid outage. In simple terms: when there is a power outage, a microgrid can isolate on-site generators or renewable energy resources from the grid and continue to operate in “island-mode,” providing power to critical loads in the facility to keep the water flowing.

And when it comes to creating more sustainable water infrastructure, microgrids can help manage distributed generation sources by providing optimal control, dynamic stability, and balancing energy demand with power generation on a small but critical scale.

What does your recent project in Columbus do? And what equipment does it include?

We worked with AEP Ohio and the City of Columbus to bolster the operational resilience and improve the environmental sustainability of the critical water infrastructure at the city’s Tussing Water Booster Station.

This project established the first renewable energy microgrid in Columbus and extended the water department’s ability to deliver safe and clean water during extended grid outages.

Components for the microgrid include 100-kilowatts (kW) of on-site solar generation, 440-kilowatt hours (kWh) battery energy storage and Eaton’s intelligent microgrid controls.

The system works by intelligently producing, storing and consuming renewable solar energy to keep pumps on and water flowing during extended grid outages.  And when the microgrid is grid-connected, the city can utilize its installed energy storage base to participate in demand response programs and reduce energy usage during peak demand periods.

Do microgrids supplement or replace existing backup generators?

The short answer is that microgrids can do both! When developing a microgrid, many factors should be explored, including existing electrical infrastructure, current generation assets, the site’s load profile and expected growth, and local utility rates including peak demand charges.

Microgrids can be configured to use existing onsite generation such as diesel generators, but you can also reduce the cost and use of fossil-fuel generators by incorporating renewable energy alternatives.  For example, the microgrid we helped develop in Columbus uses a battery energy storage system that can supply drinking water for 1-2 days without grid power, with the potential to extend backup for many days using energy supplied by the solar panels.

Microgrid controllers are the important piece of the puzzle here. The controller is the brains of the microgrid system — automatically transitioning from grid power to on-site power sources when it senses an outage.  It maintains overall system stability while dynamically managing generating assets and critical site loads by controlling where, when, and how energy is produced and consumed.

In normal grid-connected operation, a microgrid controller can also dynamically source power from onsite solar or battery storage instead of using grid power when utility prices are highest. This “peak shaving” capability reduces the costly demand charges on your utility bill.

How can you maximize the value of a microgrid system?

In addition to providing resilience and sustainability benefits, microgrids also offer the added flexibility of their distributed generation assets to provide economic benefits.  For example, installing a microgrid with solar and energy storage can offer an alternative to costly grid substation upgrades when a site’s electrical capacity needed to be expanded.

These clean energy resources can also be revenue generating. Many utilities offer incentives for participating in demand response programs to reduce a site’s energy usage during peak demand periods, or frequency regulation programs that utilize the flexibility of on-site energy storage systems to help balance the grid. 

A key consideration for maximizing the value of your microgrid is ensuring its control system is programmed and configured according to your organizational goals. This allows a water facility to utilize the most effective energy source at any given time, whether from the utility or through onsite generation sources. For example, clean energy resources will be prioritized if your goal is to decrease emissions.

What is the best way to get started on a site-specific microgrid plan?

Many questions can arise while exploring microgrid sizing and design options. No one-size solution can fit all applications. One must consider the existing electrical infrastructure and generation assets (if any), site load profile, expansion plans that may impact the site’s available capacity, utility rates and demand charges, etc.

A microgrid feasibility study is a great first step to identify the optimal power system equipment sizing, preliminary site layout, and project economics for the microgrid project in support of the customer’s objectives and use case.

A feasibility study is a step-by-step assessment:

  1. data collection for the site including load profile and power system analysis
  2. recommended distributed energy resource (DER) sizing 
  3. one-line diagram of the power system design based on system requirements
  4. project economics (ROI / NPV) incorporating available incentives

Initial screening questions touch upon functionality requirements; existing load and generation information; utility and code requirements; generation preferences; and other security and commercial aspects of the system.

For example, the screening might attempt to uncover functional specifications by exploring critical load requirements as well as any load shedding, demand response or black start (outage mode operation) needs. Peak electrical and thermal load profiles and load types must be identified prior to the design. During the screening, further assessment of existing generation and automation systems, including their scope, functionality and interfaces, should be pursued in-depth to determine more specific microgrid assets and system topology.

It is important to note that adding a microgrid and other DERs should not require rebuilding energy infrastructure from scratch. Rather it’s about adding, modifying and integrating the energy resources and loads into an intelligent microgrid system to keep the power on sustainably and affordably.

Can water departments use grants to help fund a microgrid project?

Yes. There are several clean energy incentives and grants available from the recent federal stimulus legislation that can help offset the costs of microgrid projects. On a federal level, more than $55 billion in funding from the Infrastructure Investment and Jobs Act and American Rescue Plan is targeted toward clean water and wastewater-related projects. Qualifying projects include those that help address the impacts of climate change or improve resilience for severe weather events.

In addition, local utilities often offer grants and incentives for grid interconnected microgrid systems. For example, our city of Columbus microgrid project was partially funded through AEP Ohio’s Smart City program to showcase how microgrids can deliver more affordable, sustainable and resilient energy for critical infrastructure.

Further, Energy as a Service financing is also available to help customers to install a microgrid without the upfront capital investment. This finance vehicle enables organizations to pay for clean energy as an operating expense through a 15- to 20-year power purchase agreement (PPA).

To learn more about how to leverage federal clean energy infrastructure funding for your microgrid project, I invite readers to explore www.Eaton.com/strongerfuture, where we provide guidance on navigating the government stimulus funding process as well as an overview of qualifying modernization solutions and services.

About the Author

Bob Crossen

Bob Crossen is the editorial director for WaterWorld Magazine, Wastewater Digest, Stormwater Solutions, and Water Quality Products, which compose the Endeavor Business Media Water Group. Crossen graduated from Illinois State University in Dec. 2011 with a Bachelor of Arts in German and a Bachelor of Arts in Journalism. He has worked in business-to-business journalism covering the drinking water, wastewater, stormwater and point-of-use/point-of-entry markets since April or 2016. Crossen can be reached at [email protected] or 847.954.7980.