What would happen if massive battery plant proposed in Morro Bay caught fire?

A large fire at the proposed battery plant in Morro Bay would not endanger public health, according to a safety report commissioned by Vistra Corp., the Texas-based company that proposed the project.

The battery storage project, which Vistra hopes to build on the retired Morro Bay Power Plant property, would either house lithium ion batteries in three Costco-warehouse-sized buildings or in 174 individual enclosures — enough to store 600 megawatts of electricity.

As part of the planning process, Vistra hired Ramboll, a global consultancy company, to study the impacts of toxic chemicals that could be released by a battery fire at the facility.

Scientists ran computer simulations and reviewed reports to determine the safety risk of a fire at the plant.

If one block of batteries burned at the facility while wind blew the fumes toward nearby residences, the fire would not release enough toxins to create “significant” health risks to the public based on standards set by the U.S. Environmental Protection Agency, the report said.

“Just like anything around us, it can pose a risk to human health,” report author Dr. Shari Beth Libicki told The Tribune. “But under these circumstances, the risk isn’t significant.”

The city released a draft environmental impact report on the project in March. The Morro Bay City Council and California Coastal Commission have not yet approved the project.

Meanwhile, community members have expressed strong opposition to the battery plant project.

More than 1,000 registered voters in Morro Bay signed a petition to support a ballot measure designed to block the battery plant. That measure will be on the ballot for Morro Bay voters in November.

How would Morro Bay’s stacks be demolished and a new battery plant built? See the plan

What would cause a fire at the battery plant?

According to Vistra’s plans, the plant’s batteries would be organized within the three buildings into blocks that weigh about 101,200 kilograms each.

Fire-resistant barriers would separate each block, which would be equipped with internal temperature management systems that prevent the batteries from overheating. According to Vistra, it would be close to impossible for a fire to spread from one block of batteries to another.

The company also proposed an alternative project design, which would contain the batteries in 174 separate enclosures, the report said. Each enclosure would be spaced at least 10 feet apart and separated by fire walls. It would be unlikely for a fire at one enclosure to spread to another, the report said.

Under both options, the batteries are designed to automatically shut off and disconnect from the system if they experience “abnormal conditions,” the report said, which prevents them from overheating.

If those safety measures fail, a fire could be sparked by a battery that overheats, according to the report.

Mechanical damage to the battery, a design fail, high temperatures in the facility, poor ventilation, overcharging the battery or charging it too quickly could cause it to overheat, according to the report. If safety systems fail to control the temperature of the battery, it could catch fire and spread to other batteries nearby.

Vistra Corp. plans to build a battery plant at the site of the former Morro Bay Power Plant.
Vistra Corp. plans to build a battery plant at the site of the former Morro Bay Power Plant.

What would happen during a fire at Morro Bay power plant?

The report analyzed how many pollutants nearby residents would encounter if one block of batteries burned in one of the three buildings, or if one enclosure burned in the project alternative.

According to the report, a battery fire would release hydroflouric acid, “one of the strongest acids known.” A fire would also release hydrochloric acid, hydrogen cyanide and carbon monoxide, the report said.

Inhaling each toxin in its gas form could cause a variety of symptoms, including respiratory tract irritation, tearing of eyes, sore throat, cough, chest tightness, wheezing, headache, nausea and dizziness.

Each kilogram of battery burned would release 46,228 milligrams of carbon monoxide, 11,320 milligrams of hydroflouric acid, 2,575 milligrams hydrochloric acid and 1,253 milligrams of hydrogen cyanide, the report said.

The risks to nearby homes during such a fire is low, however, the report stated.

If one block of batteries burned in one of the buildings for 24 hours, the fire would not release enough toxins to harm public health at nearby residences, according to limits set by the U.S. Environmental Protection Agency.

Nearby residences include the Morro Dunes RV Park, which would be 427 feet away from the facility. The closest permanent residences would be 1,640 feet away from the facility, while the closest school would be 2,133 feet away, the report said.

After 24 hours of burning, the amount of exposure to chemicals would be below the limits that would normally cause a person harm, the report said.

A fire burning for that length would expose someone to roughly 82% the carbon monoxide limit, 63% the hydrofluoric acid limit, 25% the hydrogen cyanide limit and 9% the hydrochloric acid limit.

If instead Vistra built the batteries in enclosures and not three large buildings, a similar fire would have an even lower impact on nearby residents, the report said.

Even if the same amount of batteries burned, the vents in the smaller enclosures are designed to release fumes in a different way so the contaminants are scattered into the air at a lower concentration.

A fire in one of the enclosures would expose the nearest residence to 40% the carbon monoxide limit, 31% the hydrofluoric acid limit, 12% the hyrdrogen cyanide limit and 4% the hydrochloric acid limit.

These are low enough concentrations of each toxin that they wouldn’t have a significant impact on the health of surrounding residents, the report said, especially when you take into account more likely scenarios.

The analysis also assumed residents would remain outside during all 24 hours of the fire, which is an unrealistic scenario, the report said.

Instead, first responders would likely extinguish the fire before it burned for 24 hours and residents would be evacuated or ordered to shelter in place during the fire, so they would inhale fewer contaminants.

How to learn more about the project

Vistra will host a public meeting at the Del Mar Elementary School Auditorium in Morro Bay from 6 to 8 p.m. on Wednesday.

There, the company will discuss safety at the plant and the different proposed designs for the project.

The meeting will also be livestreamed on SLO-SPAN.

People can submit questions ahead of the meeting online at morrobayenergystorage.com.