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- An engineer who lost his home in the Palisades fire says a new system of low-cost inflatable reservoirs could ensure more water is available to fight fires.
- The balloon-like plastic tanks, called Water Trees, were developed by a company as an energy solution.
- Now the engineer and his colleagues are proposing to install the onion-shaped reservoirs across Southern California as a solution to reduce fire risks.
When wind-driven flames raged through Pacific Palisades, Marco Terruzzin and his family were not at home. They soon learned that the inferno had destroyed the two-story Spanish-style home they had moved into just one month earlier.
As Terruzzin followed the news of the catastrophic losses, he felt powerless and was struck by the accounts that firefighters had trouble getting water because many hydrants lost pressure and ran dry.
Then the Italian-born engineer had an idea: a technology he helped invent with colleagues at his energy company that he felt certain could have helped. This solution, he thought, would ensure there is plenty of water on hand in the right places to contain wildfires and keep hydrants flowing.
“This problem must be solved,” Terruzzin said. “It’s solvable.”
The way to do that, Terruzzin believes, would be to repurpose a low-cost water-storage system that his company, Energy Vault, has in operation at a former coal mine in Sardinia, Italy. There, the system is used to store intermittent energy by pumping water uphill during the day, when solar power is plentiful, and letting water run downhill to generate power at night.
The water is stored in balloon-like inflatable tanks the company calls Water Trees, which stand 39 feet tall and resemble giant onions, each contained in a durable plastic membrane held secure by steel cables. Supported by a steel pole and a concrete foundation, each can hold about 148,000 gallons of water, weighing more than 600 tons.
Terruzzin, the company’s chief commercial and product officer, believes California should install these pop-up reservoirs in strategic locations to provide an extra supply for containing and fighting fires like those that devastated Pacific Palisades and Altadena last month.
The patented system has not yet been used for firefighting, but Terruzzin and his company soon plan to ship two prototypes from a facility in Texas so they can be demonstrated for California fire agencies.
Terruzzin envisions some of the Water Trees being placed near fire hydrants, with others arranged in rows where neighborhoods meet wildlands, creating a sort of “shield” that acts as a firebreak by spraying water to extinguish flames and drifting embers.
Firefighters in Pacific Palisades and Altadena have repeatedly been hampered by low water pressure and dry hydrants, revealing limitations in local water systems designed to supply neighborhoods.
Once the inflatable tanks are installed in high-fire-risk areas, they would be filled by pumping from the existing municipal system, and the stored water would then be isolated from the drinking water supply and kept for an emergency.
In the event of a fire, water would flow down out of the tanks by gravity. That would generate a strong enough flow to nearby fire hydrants to maintain pressure for hours, Terruzzin said.
The tanks that are lined up between homes and flammable vegetation would be equipped with networks of flexible pipes and sprinklers, which would douse a wide area to prevent flames from advancing.
“It’s ideal,” Terruzzin said. “It can be implemented today.”
He estimates that if more than 4,000 Water Trees were installed throughout the Los Angeles area, the cost would be approximately $80,000 for each one — substantially less than the cost of traditional storage tanks or reservoirs.
A Ventura County lawmaker is proposing new wildfire resilience standards that would require water providers to ensure full tanks and backup power.
A single Water Tree, Terruzzin said, can hold enough water to release about 800 gallons a minute for three hours. Installing 40 or 50 of them in Pacific Palisades as neighborhoods are rebuilt would help make the community safer, he said.
Dean Florez, a member of the California Air Resources Board and former state senator, learned about the idea from Terruzzin, who is a friend, and said he likes the concept as a “forward-thinking innovation that could change the game in how we approach wildfire preparedness.”
Los Angeles and other fire-prone areas need a decentralized water storage strategy to address the repeated problems of hydrants losing pressure and power outages cutting off access to water sources during fires, Florez said. The limitations of the existing infrastructure, he said, call for rethinking how water is stored to better defend communities.
“It seems like one of those ideas that could have been a game-changer already — if only we had started thinking bigger sooner,” Florez said. “Would that have prevented all the destruction? Maybe not. But would it have bought firefighters more time, slowed the spread and reduced losses? Absolutely.”
The concept will likely be one of many that local and state officials consider as they analyze ways of remaking water systems in L.A. and other areas to be better equipped for large wildfires.
The January firestorms revealed the significant limitations of Southern California’s urban water systems, which experts say were not designed with the capacity for large wildfires that rage through entire neighborhoods. When the system lost pressure in parts of Pacific Palisades, some hydrants ran dry in high-elevation areas, hindering the firefighting effort.
Gov. Gavin Newsom has ordered an investigation into the loss of pressure and the lack of water available from a reservoir in Pacific Palisades that was out of commission for repairs. The L.A. City Council has also ordered the city’s Department of Water and Power to present its findings on why firefighters ran out of water.
Terruzzin said he was puzzled about why officials had left the 117-million-gallon reservoir empty for nearly a year for repairs. That said, he thinks having the reservoir filled would not have fully solved the problems. The current system of pipes, he said, does not allow for shunting all the necessary water from the reservoir at once because the limited flow capacity presents a “gigantic bottleneck” — even if all the water were released, it couldn’t all get to where it needs to go.
“We need distributed water resources,” Terruzzin said. “You have water strategically distributed to protect the residential areas. We have to just bring the water nearby.”
Having Water Trees installed across L.A. could help solve this problem, he said. Valves operated with a remote control system could be quickly opened on the pop-up tanks to send water into pipes and “make sure that there is higher pressure in the system” whenever a fire is causing heavy demand. And the gushing spray from tanks on hillsides, he said, would flood the landscape to keep flames at bay.
Terruzzin has spent years working on energy storage projects that reduce carbon emissions to help address climate change. The energy storage project with Water Trees began operating in Italy last year.
The company began studying the possibility of using the inflatable tanks for firefighting after deadly 2023 wildfires in Greece. But it was only after the Palisades blaze, Terruzzin said, that he and his colleagues “connected the dots and realized that this solution must be implemented.”
The Water Trees, which the company plans to produce in the U.S., will hold water in a 4.8-millimeter-thick plastic membrane designed to resist fire and last for more than 20 years. Terruzzin said the reservoirs, which are 35 feet wide, were designed in the shape of a water drop, an optimal form as gravity pulls down the massive contents.
Water experts who were shown information about the concept said it seems promising, though they also raised some questions.
“Los Angeles needs more water storage capacity, particularly in elevated areas, for fire protection,” said Sanjay Mohanty, an associate professor of engineering at UCLA. “Investing in these systems can be beneficial.”
Mohanty said he sees several challenges, such as complying with drinking water regulations and demonstrating the system would be safe in an earthquake. (Terruzzin said the system has been tested to withstand quakes.)
“They have also to demonstrate that the amount of water needed is actually going to make the difference that they plan to,” Mohanty said. “There are a lot of calculations to go, but we need reservoirs and that definitely is a very promising technology to put in a location where you can’t have a large reservoir.”
The California fires erupted amid extremely dry conditions. UCLA scientists say extreme heat linked to climate change was a factor in the fires’ intensity.
Upmanu Lall, director of Arizona State University’s Water Institute at the Julie Ann Wrigley Global Futures Laboratory, questioned how much the tanks would effectively reduce losses in fires.
“That would depend on the scale of deployment, because if you can’t get a high density of deployment, you’re not going to really reduce the losses very much,” Lall said. Also, he said, strategically choosing where to install the tanks would be particularly important.
Another challenge, Lall said, would be persuading homeowners to allow large onion-shaped reservoirs in their neighborhoods and in the natural landscape.
“How socially acceptable is it, to these high-net-worth individuals, to have these balloon-looking things sitting behind them?” Lall said. “Of course, you have to get the public buy-in.”
Terruzzin agreed that “some work has to be done” to make the big white drops “aesthetically acceptable.” But as he sees it, the balloony blobs can be like freeways: functional and necessary.
“Without new infrastructure that helps California to have water available in the right place at the right time, you don’t solve the problem of these wildfires, and they will be more and more frequent,” Terruzzin said.
The costs of investing in this type of solution, he said, would be small when compared with the risks.
