Can Microgrids Make Water and Wastewater Treatment Plants More Resilient?

Natural weather events like Hurricane Ida, last winter’s arctic freeze in Texas, and Midwestern tornadoes can cripple America’s water and wastewater treatment facilities’ ability to deliver essential services to customers in an affordable manner. Municipalities and operators are looking for solutions that will strengthen their resiliency and keep their operations running smoothly and affordably for customers. One solution Solential Energy believes deserves a serious look is microgrids.

Eight days after Hurricane Ida slammed into Louisiana, news outlets reported that more than 700,000 customers of the primary electrical utility company, Entergy, were still without power due to widespread power grid destruction and failure. Eight days. No power. No water. No gas. And sweltering temperatures.

People were literally stuck in a no energy twilight zone. Many communities, if they had water, were having to boil it before drinking it. Those without water were forced to take desperate measures like raiding swimming pools for water to bathe and  flush toilets. Just thinking about the heat, no water, no working bathrooms, and no gas to put in my car and escape is hard for me to stomach.

Entergy announced it was restoring power to critical infrastructure first – hospitals, nursing homes and first responders. (We’re wondering why water and wastewater plants are not considered critical infrastructure.)

If there is some good news out of all this, it’s that Entergy expected most New Orleans residents would have their power restored by Wednesday, September 8. Still, it will take until the end of September for more rural parts of the state to have power and water restored.

No power means big problems for water and wastewater treatment facilities

Water and wastewater plants depend on huge quantities of energy to operate. Without power, they are dead in the water.

Let’s look at drinking water first. Unexpected power losses are devastating. As we’re seeing in Louisiana, inoperable pumps at a water utility mean there’s no clean water for drinking or bathing. But it also means there’s no water for fire departments, hospitals and nursing homes, stores and restaurants. Pressure losses can allow contaminants to enter the drinking water distribution system from surrounding soil and groundwater. Major storms can damage water pipes themselves, meaning more interruptions.

Power failures are equally troublesome for wastewater utilities. When pumps fail, untreated sewage can be discharged into rivers and streams. This can also cause sewage backups in homes and businesses. That’s definitely not very pretty when people are already suffering. Power losses also impact industrial customers that rely on wastewater treatment to keep their operations safe.

Energy resilience is the answer. But what does that look like?

In an ideal world, water and wastewater treatment facilities would weather storms without flinching. However, none of us have truly figured out how to beat Mother Nature. The best defense is a good offense and the U.S. Environmental Protection Agency (EPA) has put together a helpful introduction on how to achieve energy resilience.

The first step is to conduct an energy risk assessment that identifies exactly how much energy is needed to power the overall facility as well as essential equipment during a power interruption. This assessment should include quantifying energy use over various increments of time (days/weeks/months) and even different seasons when the plant’s load and energy requirements can vary. These data points will dictate alternative power sources needed over the short and long terms.

In the short term, generators

For short-term resiliency, the EPA recommends having emergency/standby generators to keep a facility operational during a storm-related energy outage or temporary grid failure. Options include fixed or portable emergency generators, the latter giving municipalities with multiple facilities the flexibility to take generators to where they’re needed. Generators must be properly sized based on energy needs as well as safely installed, preferably in weatherproof enclosures.

Facilities should also have plans for having enough fuel for generators during a power outage emergency. Diesel and natural gas are the common options. Fuel tanks must be placed above potential floodwater levels.

If your plant decides to install back-up generators, you really need this: an automatic transfer switch (ATS). This prompts the generator to automatically kick in when it detects power from the main grid has been lost. Once power from the main grid is restored, the generator will then be prompted to shut off. Without an ATS, a plant operator needs to be on-site to manually flip the switch on the generator in the event of a power outage and manually turn off the generator once power is restored. In the middle of a hurricane, who wants to have to flip a switch?

Which brings us to the longer-term – and intriguing – solution, on-site microgrids

Among the keys to long-term energy resiliency for water and wastewater facilities is having the ability to operate independently of the centralized energy grid by having a microgrid with distributed energy resources within clearly defined electrical boundaries that enables the facility to operate as an autonomous energy island. The microgrid generates its own energy to power its operations while still remaining connected to the grid and having the ability to pull energy from the grid when needed.

Microgrids increasingly employ a mixture of different distributed energy resources, including photovoltaic solar, wind turbines and biogas, which in addition to being renewable, significantly reduce carbon emissions. Because they can operate independently of the centralized grid, microgrids strengthen grid resilience and help mitigate grid disturbances. Microgrids remain connected to the centralized grid.

There are a number of distributed energy resource options a microgrid can employ in combination. Renewables are increasingly popular because of low cost and minimal, if any, environmental impact. We have to be honest, Solential is partial to option one:

• Photovoltaic solar panels absorb sunlight to generate electricity. They can be installed in a variety of ways at water/wastewater utilities including ground mount, canopy, rooftop systems., and our favorite, floatovoltaics, where solar panels on a floating structure are installed on lagoons and reservoirs.
• Anaerobic digestion of biomass and waste methane can be pressurized and filtered as a low-BTU natural gas to
  produce electric power and heat. Over 600 wastewater facilities utilize their waste gas for energy.
• Combined Heat and Power (CHP) is the simultaneous generation of electricity and heat from a source such as
  biogas, natural gas or co-mingled gas. CHP technology is particularly attractive at wastewater treatment plants with anaerobic digesters, which produce biogas as a waste product.
• Wind turbines convert kinetic energy from wind into electrical energy and can be installed at utilities.
• Battery banks store energy from the grid or from on-site renewable sources such as solar and wind that generate power only during certain times of the day.
• Fuel cells convert energy either natural gas, biogas, or hydrogen into electricity through a chemical reaction.
• And finally, traditional fuel-burning generators.

Which brings us back to our question: can microgrids boost resiliency of water and wastewater treatment plants?

From Solential’s perspective, yes.

Let’s use New Orleans as an example. Let’s imagine their drinking water plant had a microgrid that they powered by solar, combined heat and power using natural gas, with generators as backup. When Ida took the city’s energy grid offline, cutting off power to everything across the city, the water plant would have disconnected from the grid in favor of its own electricity-producing microgrid. Relying on a microgrid during the major outage would have enabled a ”Big Easy” water plant to continue making safe, drinkable water uninterrupted.

Think how much easier and less stressful life would be for communities in the wake of severe weather calamities if their water treatment plants had microgrids. So yes, we believe microgrids, when carefully, strategically, and professionally planned and executed with industry experts, can bring resiliency to water and wastewater treatment plants. Solential Energy has partnered with Trane Technologies to make it happen for municipalities across the Midwest.

If you have questions about microgrids and how Solential can help make your water and wastewater treatment plants more resilient in the face of  severe weather or other natural disasters, please connect. You can reach me at cmiller@Solential.com and via text or phone at 317-627-4530.

NOTE: Per the EPA, distributed energy resources and microgrids are emerging technologies. Operators need to check your state regulatory commission rules on grid interconnection if the system is to interface on-and-off the electric grid. If the microgrid is only dedicated to critical loads, you may not need to address those regulatory issues. The EPA offers a number of energy resources on renewable energy, energy efficiency and emerging technologies.