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District to study ways to make power system more resilient

By July 25, 2023

The phone call on Feb. 15, 2021 came as a shock.

Most of Texas was dealing with a paralyzing winter storm and electricity providers were on the line telling Tarrant Regional Water District officials that the electrical grid may be taken down. Without warning.

TRWD had made adjustments to its operations, but shutting down power would make it hard to provide water to over 2 million people and possibly damage its pumps and pipelines. The electric utilities agreed to keep the power on.

“The grid got really close. It was a matter of minutes away from a failure and it would take a while to get it back up,” said Zach Huff, TRWD’s water resources engineering director.

While TRWD was already thinking about how it can provide water during sustained power outages or a power grid failure, the 2021 winter storm convinced officials to see what it can do to make the system more resilient.

As a result, the TRWD recently approved a six-month, $289,755 study by Black & Veatch Corp. on how to improve the reliability of the power system needed to supply water throughout the system during an emergency.

Besides looking at operating in short-term and long-term power outages, the study will also help TRWD examine how it can control overall energy costs during routine operations, such as on hot summer days when power is expensive.

For the first time TRWD will use a consultant to study the feasibility of solar power generation on its land in East Texas to help power its massive pumps.

“We’ve been thinking about backup power at key pump stations for some time, but (the 2021 storm) was the catalyst,” said Jason Gehrig, TRWD’s infrastructure engineering director. “We have to have more control over the situation.”

Devin Taylor, TRWD’s energy manager, said the District has established policies of what to do in a power emergency and he stresses that they never lost power in 2021. But a closer look is still needed, he said.

“This study is looking to add a little more depth to that resilient plan,” Taylor said. “We were resilient in 2021, and we want our system to remain resilient to unforeseen power outages in the future.”

TRWD provides raw water to four major customers in North Texas: Fort Worth, Arlington, Mansfield and the Trinity River Authority. Overall, TRWD supplies water to 2.3 million people in 11 North Texas counties.

The first phase of the study will be a high-level alternative analysis of the feasible resilience, generation and energy system technologies available at each of TRWD’s pump stations. It will identify the most likely options while taking into consideration budgetary costs.

The next two phases will look at operations at the Benbrook Lake Pump Station and the Benbrook Booster Pump Station in the western portion of the system, and at the Joint Booster Pump Station 3, Joint Cedar Creek Lake Pump Stations and the Cedar Creek Lake Pump Station in the east.

During the 2021 storm, Benbrook’s pump stations were critical after operations at Richland Chambers and Cedar Creek reservoirs had been shut down to not only protect the grid but to safeguard the pumps from a sudden power failure.

By using water that had been stored in balancing reservoirs closer to Fort Worth, TRWD was able to pump up to 536 million gallons a day throughout its system, more demand than what it encounters on a dry summer day.

Several backup diesel generators – some as big as semi tractor trailers – may be needed to run Benbrook’s pumps for several days during an emergency, Taylor said. “We don’t have small loads,” he said.

Solar power is at the center of the detailed analysis for the Joint Booster Pump Station 3, Joint Cedar Creek and the Cedar Creek Lake pump stations.

With the land TRWD already owns in East Texas, the District is looking at a large solar array as an alternate power source, and not just for use during emergencies, said Rick Zarate, TRWD’s project manager for the power study.

TRWD officials have already done enough “back of the envelope calculations” to know it is feasible, Zarate and Taylor said. The power study will let them know if their preliminary estimates are accurate. It will also consider ownership models for solar power and what the risks and benefits there could be for owning the system. It will also look at outsourcing the project with a private company to maintain and operate the system.

“It will look at the feasibility of solar generation in our system,” Zarate said. “How would we use it? How big would it be? What’s the best place for it?”

TRWD budgets $18 million a year for energy costs, but it pumps more water during the dry summer months of June, July, August and September. That is when demand for electricity is higher and more expensive.

TRWD pre-purchases energy at a fixed price from various providers, including those using solar technology, to cut back on the amount of power it must buy on the open market. TRWD also monitors its time-of-day usage and reduces its energy consumption during peak hours to minimize electricity costs.

Zarate said the study will look at the “peak shaving” incentives – which refers to reducing peak electricity use by industrial and commercial consumers – in conjunction with resilience planning.

“TRWD can produce its own electricity and reduce the amount of energy purchased from the utility companies during peak energy demand hours; peak shaving could result in energy cost savings to our customers,” he said.

Lastly, the study will explore what alternative funding sources are available for agencies like TRWD for purchase, installation and maintenance of backup generation and solar generation systems.

For example, this year, the Texas Legislature approved $1.8 billion for institutions like hospitals and utilities to buy backup generators.

“This study will help TRWD confirm whether back up power and or solar generation for system resilience make sense from an economic, engineering, operational, and maintenance perspective,” Zarate said. “We’re doing our due diligence to help our system, to make sure we can operate no matter what.”

While Gehrig said whatever is proposed must make economic sense, he remembers all too well how dicey the situation became in February 2021.

“It’s one of those things that you’re not going to see a lot of time and hours on these generators, but when they do run, they are mission critical,” he said.

 

Lake Current Level Conservation Level* Level Difference**
Arlington 548.24 550.00 -1.76
Benbrook 694.06 694.00 0.06
Bridgeport 826.25 836.00 -9.75
Cedar Creek 321.75 322.00 -0.25
Eagle Mountain 647.78 649.10 -1.32
Lake Worth 592.04 594.00 -1.96
Richland-Chambers 315.49 315.00 0.49
*Conservation Level: The permitted level of water an entity is allowed to hold in a lake. Any amount above the conservation level is used for the temporary storage of flood waters and must be released downstream.
**Difference: Amount above or below conservation level.
For more information read our daily reports or the TRWD Lake Level Blog.

Check out the TRWD OneRain portal for a visualization of this information and more.

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