Hurricane Hanna Demonstrates Value of Microgrids for 30 MW of Texas Load

Hurricane Hanna offered a case study in the value of microgrids when it hit the Texas Coast near Corpus Christi on July 25, causing widespread power outages.

The hurricane dumped up to 18 inches of water in parts of Texas and about 200,000 utility customers lost power, some for more than two days.

However, as the hurricane approached the state, Enchanted Rock, a microgrid company based in Houston, islanded 27 of its customers from the grid, insulating them from possible power outages, according to Allan Schurr, Enchanted Rock chief commercial officer. The islanded sites represented about 30 MW of load.

Eleven of the islanded sites had surrounding power outages, with one lasting more than 49 hours and two others continuing for 44 hours, Schurr said.

In several cases, there were multiple outages in the area, with power being restored and then cutting out a short time later, according to Schurr.

Concern about extreme weather — storms, fires and floods — is contributing to interest in microgrids, Schurr said, pointing to an unexpected storm in the Dallas area in June 2019 that knocked out power to around 350,000 customers, with some outages lasting days.

“Businesses are starting to plan for contingencies,” Schurr said, noting the novel coronavirus is increasing the focus on risk management. “We don’t need disasters on top of disasters.”

Grocery stores, for example, are now deemed essential and healthcare facilities are more focused on their power requirements, Schurr said. Most hospitals only have backup power for their critical facilities, he said.

Enchanted Rock manages its customers’ microgrids from its network operations center in Houston, but also positions technicians near the islanded microgrids to handle any onsite problems if they arise, Schurr said.

The microgrids affected by Hanna use natural gas-fueled generators to provide power, which are supplied by underground lines that protect the fuel supplies from disruptions, Schurr explained.

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In contrast, backup diesel generators can face fuel supply disruptions during storms, Schurr said. Also, facilities that use backup generators can face outages before they start up and when they cut over to grid power, he said.

Diesel generators also need regular testing and, even during testing, produce air emissions that can be significant, Schurr said.

Several years ago, the Texas-based H-E-B grocery store chain decided to move away from its fleet of mobile backup diesel generators and became an Enchanted Rock customer, Schurr said.

Without power, grocery stores quickly lose perishable products, which can cost them $100,000s, depending on the length of the outage, according to Schurr.

By using its microgrid generators in wholesale markets, Enchanted Power is able to offer microgrids that are less expensive than diesel generators, according to Shurr.

Enchanted Rock is focused on California, the Southeast, Texas and the Midwest. The company has 170 microgrids totaling about 250 MW and is building 100 MW in microgrid capacity.

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