The appeal of fuel-agnostic power generation

As the current energy crisis vividly illustrates, the withdrawal pains associated with ending the economy’s fossil fuel addiction and moving to clean, renewable sources are deeply painful. While purists and progressives champion a cold-turkey approach, reality requires the transition to alternative fuels for electricity and transportation to be more like an extended rehabilitation program.

That’s one reason I’m intrigued by a announced this morning by Mainspring Energy, the well-funded company behind a revolutionary redesign of electric generators — one that will help its customers avoid investing in climate tech that quickly becomes obsolete.

What makes Mainspring’s tech unique? Rather than relying on rotating magnets to generate electricity — as most engines have for more than 200 years — its technology is linear, sliding back and forth to produce power.

Most of the Mainspring models out in the field today, used by companies including Kroger, Lineage Logistics and NextEra Energy for on-site power generation and grid stability, are fueled by natural gas or biogas. The breakthrough is this: Soon, the generators will be able to run 100 percent hydrogen and 100 percent ammonia fuels directly, alongside other gaseous fuels. It’s the customer’s choice. That means as these fuels become commercialized, older Mainspring units can be retrofitted to use them. And early adopters can have more confidence that the investment won’t be short-lived, as is often the risk with emerging climate tech.

“Clean fuels are essential to decarbonizing the grid and supporting the rapid growth of solar and wind power,” said Mainspring CEO and founder Shannon Miller in the press release announcing its technological advance. “They provide all the advantages of fossil fuels — resilience, low-cost cross-seasonal storage and ease of transport — without the carbon.”

The viability of hydrogen and ammonia as clean, or at least cleaner, fuel sources is a matter of hot debate. Clearly, support for their potential to reduce the emissions of heavy-duty transportation, power generation, chemical production and so forth is building. South Korea, for example, is pushing clean hydrogen as an important part of its clean economy future, projecting that it will account for about one-third of its energy by 2050. But just how “clean” these fuels really are relates directly to the fuel used to power their production. The only true “green” hydrogen is that which is produced with relatively solar or wind power, still a rare commodity.

[Want to learn more about how climate tech can help us address the climate crisis? Check out VERGE 22 — the climate tech event — taking place Oct. 25-27, San Jose, CA.]

When I spoke with Miller about Mainspring’s new technology, which should be part of commercial units by the end of next year, she said her company is using its fuel-agnostic future to provide more confidence to commercial and industry customers looking to get off diesel generators , responsible for coughing up both substantial emissions and soot. In California alone, the collective power of diesel generators in the field today is about 12 gigawatts, or roughly 15 percent of the state’s total grid capacity. Ammonia, in particular, promises to be a high potential alternative for replacing diesel, she said.

One of the biggest challenges associated with running alternatives such as hydrogen or ammonia is that there can be performance disadvantages, when compared with fossil fuels sources. According to a company FAQ, there is a “slight decrease” when running the Mainspring linear generator on hydrogen. The ability to run on pure ammonia is unusual; fuel cells, as an example, must convert ammonia to hydrogen, which results in an energy efficient loss of 20-30 percent.

To a large extent, the fuel mix used by a given Mainspring linear generator can be controlled using software, which gives it more flexibility than alternative technologies such as fuel cells or combustion engines, according to Miller. “You can move the oscillators to any position. It is all software-controlled,” she said.

Mainspring’s latest announcement comes just a few weeks after it disclosed a big order from cold-storage warehouse operator Lineage Logistics, which plans to install up to 150 linear generators across its distribution facilities. In late May, the company also disclosed that it has closed more than $150 million in its Series E round from the likes of Lightrock, Khosla Ventures, Bill Gates and several other investors. That brings Mainspring’s funding total to $391 million, although the Series E fundraising isn’t over yet.

Mainspring also has a $150 million financing partnership with NextEra Energy that provides energy-as-a-service contracts for commercial and industrial customers that don’t want to take on the capital investment. When I asked about pricing, Miller declined to be specific but said the costs associated with the linear generator are similar to those for a conventional engine and lower than for fuel cells. The technology’s footprint requires roughly the size of a parking space.

A fuel-agnostic future?

To be clear, Mainspring Energy isn’t the only company talking up fuel flexibility. One of the world’s biggest combustion engine companies, Cummins, in February announced powertrain technology that will also support a transition to alternative fuels. Its new “fuel-agnostic” equipment is capable of running diesel, natural gas and hydrogen.

Here’s one benefit touted in its press release: “This means it will be easier for OEMs to integrate a variety of fuel types across the same truck chassis, and there will be minimal costs to train technicians and re-tool service locations, resulting in a lower total cost of ownership for the end user.”

Some companies that use Cummins for engines include Paccar, Navistar International, Volvo Trucks North America, Daimler Trucks North America and Ford.

Flexibility during the transition will be key, a concept that both Mainspring and Cummins are touting. “Having a variety of lower carbon options is particularly important considering the variation in duty cycles and operating environments across the many markets we serve,” said the president of the Cummins Engine Business, Srikanth Padmanabhan, in the press release about the new technology. “There is no single solution or ‘magic bullet’ that will work for all application types or all end users.”

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