Can mobile batteries make dirty diesel generators obsolete?

Batteries are already powering cars, trucks and buses, and backing up homes, businesses and the grid. So can they also replace the ubiquitous but dirty diesel generator? 

Staid corporations and plucky startups have been trying to answer that question for more than a decade, with relatively little success. But with battery costs falling, performance improving by leaps and bounds, and demand for carbon- and air-pollution-emissions-free mobile power sources growing, the moment for the battery-powered generator may have finally arrived.

Paul Huelskamp, co-founder and CEO of mobile battery systems startup Moxion Power, certainly thinks so.

“Temporary power is a huge market,” he said, with various estimates pegging it at between $4 billion and $6 billion per year globally, and it’s primed for rapid growth. And the diesel generators that make up the vast majority of that market ​“are terribly inefficient and terrible for the environment,” emitting more than twice the carbon dioxide per unit of electricity produced than U.S. grid power on average, as well as significant amounts of particulate matter, volatile organic compounds, nitrogen oxides and other harmful pollutants.

In contrast, Huelskamp said that battery-powered generators can provide quiet and emissions-free electricity much more efficiently and reliably, as long as they’re designed to meet the remote-power market’s needs. He also claims that despite their higher upfront cost, they are less expensive than diesel on a long-term basis because electricity is cheaper than diesel, maintenance costs are lower, and battery prices continue to fall each year.

Plus, he said of diesel generators, ​“Someday they’ll be illegal, at least in California.”

Huelskamp’s company is far from the only one making such claims. Startups and major manufacturers alike are vying for a share of the emerging clean energy sector, which may be comparatively small now but could someday come to be a crucial form of clean power for some of the biggest industries in the world, such as construction and film production, which currently rely heavily on diesel-powered generators.

Why mobile batteries haven’t boomed — yet 

Given all of these advantages, why haven’t mobile batteries replaced generators already? Huelskamp points to a combination of technology, reliability and market inertia. 

Early efforts to replace generators with batteries had to work with much more expensive and less capable battery technologies, putting them at a disadvantage. Big rental operations including Sunbelt, which provide the lion’s share of generators to end users like construction firms and film studios, have been leery of working with new companies providing untested products.

And there has been at least one spectacular flameout in the mobile battery industry — DC Solar, another Northern California company that grew to billions of dollars in sales of its solar-panel-charged battery trailers before collapsing under its fraudulent business practices. In 2021, DC Solar CEO Jeff Carpoff was sentenced to 30 years in federal prison for orchestrating a massive Ponzi scheme that included sales of imaginary equipment to companies seeking to offset their tax liabilities via solar tax credits.

But this black eye for the mobile-battery business model hasn’t altered the fundamentals that have now made batteries an increasingly cost-effective alternative to fossil-fueled generators.

Mobile battery power centers have become ubiquitous in the consumer market, powering campsites, RVs and homes during blackouts. Automakers including Ford have made mobile and emergency power a central plank in their EV marketing. And firms in the construction space are getting involved too — for example, Volvo Construction Equipment inked a deal with Portable Electric, a mobile power startup that recently announced plans to scale up production to 2,000 units per year.

For its part, Moxion’s earliest deployments include a stint at this year’s BottleRock music festival in Napa, California and at two Amazon video productions. And in March, major mobile equipment provider Sunbelt Rentals placed an order for more than 600 of Moxion’s battery systems to be delivered over the coming year.

Some of these firms are also investors in Moxion, with Amazon and Sunbelt both contributing to its $100 million Series B round led by Tamarack Global last September. With the funding, the company aims to scale up its Richmond, California–based factory to manufacture 10,000 systems per year.

Global generator makers have parlayed their experience integrating batteries into remote and off-grid applications into mobile equipment as well. Notable examples include major U.S. engine and generator manufacturer Briggs & Stratton, which acquired battery startup SimpliPhi Power last year and now offers its smaller-scale mobile batteries for use in outdoor applications. Generac, a major maker of generators that’s built a backup battery and grid services business via acquisitions, offers mobile skid-mount battery systems alongside its diesel- and fossil-gas-fueled systems.

But for larger-scale mobile power systems, major generator manufacturers have combined batteries with fossil-fueled engines to improve performance and efficiency rather than promoting battery-only configurations. Huelskamp noted that these companies remain wedded to existing business models that earn significant revenue from aftermarket service and parts sales.

“Every R&D dollar they invest” in battery-only technology ​“is going to cannibalize revenue from their existing business lines,” he said. ​“I think they’re going to move very slowly and be very thoughtful and careful” — a strategy that ​“means companies like Moxion have a huge window to get to scale and get on a level playing field.”

As for the perennial question about batteries — how long do they last? — Huelskamp said Moxion Power’s 600-kilowatt-hour systems can ​“last multiple days, and in most cases weeks, before they need to be recharged” — just as long, if not longer, than a generator can run before needing refueling.

Despite these improvements in battery capacity and runtime, hybrid generator-battery designs may help ease concerns about the reliability and durability of battery-only mobile power units. Even well-tested and capable battery systems can expect to face lots of questions, and the well-publicized failures of DC Solar’s systems in the field haven’t helped.

Last month, decarbonization think tank RMI and its climatetech accelerator Third Derivative launched a Clean Mobile Power Initiative with Netflix and Disney aimed at solving these problems. (Canary Media is an independent affiliate of RMI.) The goal is to ​“accelerate the deployment of clean mobile power technologies and support alternative solutions in the entertainment industry,” where generators account for about 15 percent of a film set’s total carbon emissions.

The initiative has set some key operating criteria to select winning technologies. Besides meeting core safety and reliability standards, those include being able to provide up to 220 kilowatts of three-phase power on demand for up to 14 hours, being able to be towed by a medium-duty truck and fit inside a standard parking space, and preferably being able to provide fast-charging for electric vehicles.

“There’s growing demand and availability of potentially viable alternatives” to those generators, said Caroline Winslow, Third Derivative’s acceleration strategy manager. What’s holding back their widespread adoption is ​“really the scale and availability” of the products, she said.

The other key challenge is the ​“disaggregated group of stakeholders, from procurement through deployment,” that make decisions about what mobile power system to use, she said. A typical film production can spend days setting up the generators and cabling needed for cameras, lighting, sound recording and mechanical equipment like cranes and dolly carts — and that’s not to mention the needs of the transportation department, food services, trailers and other power users.

And because both Disney and Netflix rent their mobile power equipment, the companies that provide that equipment will ​“play a key role in de-risking these technologies, testing them on their rental lots and verifying their capabilities,” she said.

Solar-charging emergency services and utility backup batteries 

Mobile battery units also boast one potentially huge advantage over diesel generators: they can be self-charging.

That’s how startup Sesame Solar has approached the challenge of replacing diesel generators with batteries for its chosen target market of emergency services.

Sesame Solar’s battery and solar-equipped trailers have been used by Comcast, Cox Communications and public emergency services agencies to provide mobile power, communications and water purification after disasters like 2021’s Hurricane Ida, which knocked out power for more than 1 million customers in Louisiana.

After Hurricane Ida, ​“there was plenty of diesel fuel, but they couldn’t get it out of the ground without power, and they couldn’t get the fuel trucks in” due to flooding, Sesame Solar CEO Lauren Flanagan said. Comcast used her company’s trailers to power crisis response centers, offering cellphone recharging, Wi-Fi hotspots and toilet and shower trailers.

These self-contained trailers, which include interior workspaces that can be reconfigured to provide communications, logistics or medical services, are quite a bit more elaborate than the mobile battery units from Moxion and Portable Electric. Sesame is working with the U.S. Air Force to test them as mobile medical centers and search-and-rescue support systems, with plans to integrate hydrogen fuel cells and electrolyzers to generate on-site fuel as well as solar-generated electricity.

This modularity is ​“a really important part of our design,” Flanagan said, to ​“be flexible to changing market trends or new technologies.” 

Moxion Power has taken a different tack, designing its own proprietary battery modules, power conversion systems and software in a vertically integrated technology stack. But Huelskamp also anticipates a need to stay flexible and be ready to develop different configurations of technology to meet changing market needs.

In particular, he’s hoping to one day crack into the major market of utilities. If successful, it’d be a full-circle moment for the company. Huelskamp and Moxion co-founder Alex Meek got the idea for the startup during a hike in the Northern California woods, when they came across a roaring and fuming diesel generator deployed by Pacific Gas & Electric to support a town that had lost power during one of the utility’s frequent wildfire-prevention grid blackouts in 2019.

During that year of wildfire threats, ​“I lost power about four or five times at my house, sometimes for days,” he said. ​“And generators were popping up all over — at grocery stores, at traffic lights, at my neighbors’ homes.”

California Governor Gavin Newsom chose Moxion’s Richmond factory as the site of his May unveiling of the state’s latest clean energy transition plan, which calls for an unprecedented scale-up of clean energy. At the same time, Newsom’s administration has approved a multibillion-dollar grid resiliency plan that has allowed diesel generators to exceed air pollution restrictions when the state’s grid faces the threat of heat-wave-driven blackouts.

Mobile batteries could supplant fossil-fueled generation for power outages and grid-reliability ​“edge cases” like localized grid outages, Huelskamp suggested. ​“The electrification of everything and the movement toward distributed generation are changing utility business models,” he said.

And with climate change driving increasingly extreme weather that’s causing more grid-reliability risks, utilities and regulators need to plan ahead to make sure that the backup power being deployed to ride through power outages isn’t causing even more environmental damage. As with so many aspects of climate change, ​“nobody pays attention to it until it’s a problem — and now, it’s a huge problem.”