In Anchorage, a coal-inspired startup could help pave the path to wind and solar

Cache Energy’s technology charges limestone based pellets inside this cylindrical container, and stores them until wind and solar power are scarce. (Photo by Nathaniel Herz/Northern Journal)

Electric utilities in Alaska and around the world are trying to cut their consumption of coal and gas, and switch to renewable power sources like wind and solar energy.

But there’s one big obstacle to completely phasing out fossil fuels: The wind doesn’t always blow and the sun doesn’t always shine — meaning that those sources alone can’t match demand 100% of the time.

Green energy skeptics cite that problem in arguing that utilities will continue depending on fossil fuels for decades. 

But a new company that wants to use Alaska as a testing ground is part of a growing industry that could prove those skeptics wrong — and help the state transition to generating much more of its power from wind and solar amid an impending shortage of utilities’ primary fuel, natural gas.

Cache Energy, run by an immigrant from India’s coal country, publicly unveiled its technology last month at a dusty Anchorage industrial lot — with backing from multinational energy company Halliburton and plans to test the system in Kotzebue next year. 

Cache’s technology aims to capture excess power from wind and solar generation and save it until it’s needed.

The company is one of innumerable businesses around the world attracting huge investments to try to crack the challenge of what’s known as energy storage — essentially, how to build better, cheaper battery systems that can charge up on unused renewable energy, then send out power when it gets dark or calm.

There are already many traditional batteries tied into electrical grids that help integrate renewables. But the lithium-ion technology most batteries depend on lasts only a few hours, and uses metals that can come from environmentally damaging mines in developing countries — driving interest in alternative energy storage systems.

One scenario to put the globe on a path toward net zero carbon emissions, published by the International Energy Agency, calls for a 35-fold increase in storage capacity between 2022 and 2030. An industry-supported study by the consulting firm McKinsey says investment in energy storage could exceed $3 trillion by 2040.

Energy storage startups have been testing new technologies that could augment or replace traditional batteries.

One other existing tool is what’s known as pumped hydro, where water can be piped up into a reservoir when renewable energy is plentiful, then released through a turbine to generate power when wind and solar are scarce. 

But such projects are difficult to permit, and expensive. Entrepreneurs are now developing concepts that include pumping water into and out of pressurized underground reservoirs; a similar process using pressurized air; even storing renewable power by hoisting huge blocks of dirt into the air, then discharging the saved electricity by spinning turbines as the blocks are lowered.

Cache Energy’s presence in Alaska, experts said, shows how businesses are scrambling to solve some of the technological problems posed by the transition to renewable power.

“It’s super relevant to the broader conversation, right now, about: What do we do with our looming natural gas shortage? And what technologies might we want to bring online on the short term to keep energy costs as low as possible — and to allow for the rapid deployment of renewables?” said Isaac Vanderberg, chief executive of Launch Alaska.

Vanderburg’s organization is an Anchorage-based nonprofit that links new companies developing climate technology, including Cache, with potential customers and host communities in Alaska.

Cache has developed a new energy storage system that stores power in tiny, white pellets derived from limestone, a cheap, abundant material.

Its process involves using renewable power to heat the pellets, which has the effect of changing their chemical composition and, essentially, charging them. When moisture is blown over the charged pellets, they release heat, which can be used to run generators when there’s a shortage of renewable power.

The idea of using lime for energy storage is an old one, said Arpit Dwivedi, Cache’s founder and chief executive. But the material’s durability has been a problem — it can crumble if it gets too hot or if it’s heated repeatedly.

Cache’s innovation is to chemically process the lime, which Dwivedi said allows the pellets to hold their strength as they’re heated and cooled multiple times. The company’s technique, he said, is patented, but it’s Cache’s “secret sauce” and he declined to discuss the process in detail.

Cache’s system works by moving pellets into a cylindrical tank, where they’re charged using heating rods, then moved into storage. The pellets could be kept in shipping containers or silos, with a couple of containers providing enough heat to warm a few large buildings through the winter, according to Dwivedi — who said the pellets will hold their charge for weeks or months even at Arctic temperatures.

The vision, Dwivedi said, was driven by his upbringing in India, where his family members worked in the country’s huge coal industry.

After studying and working in India, he moved to Illinois in 2017 to launch a new business, then obtained a doctorate in energy storage. His vision was creating a power source that had the same advantages as oil, gas and coal, without the carbon emissions, he said.

“Cache was inspired by fossil fuels,” he said. “When we were thinking about the problem, we were thinking, ‘What do fossil fuels do really well?’ They’re cheap materials that can store energy in a stable way, and you can ship them around.”

Cache, which is headquartered in Illinois, is still in its early stages, and the system — which will likely cost customers a few hundred thousand dollars apiece — has not yet been used commercially. 

But the company has already raised $8.5 million from investors that include Halliburton — a company known for its long history providing services to oil companies that’s now also branching into alternative energy sources. Cache’s Anchorage demonstration project is set up at Halliburton’s industrial lot.

“It’s a great example of the massive global energy innovation economy, with traditional players investing into the future,” said Matt Perkins, chief executive of Alaska Renewables, a company that’s developing major wind projects in the state. 

Perkins visited Cache’s project last week and described it as “one more tool in the toolkit to solve the Cook Inlet gas shortage as quickly and cost-effectively as possible.” 

Perkins noted, however, that other, existing energy storage technologies should meet urban Alaska’s needs until its utilities dramatically increase the 2% of their power that they currently generate from intermittent sources like wind and solar. Even then, Cache’s technology will have to compete against those existing storage technologies — from lithium-ion batteries to pumped hydro to reservoirs that can store and discharge natural gas.

Still, Cache is drawing intense interest. More than 200 businesspeople, elected officials and others have toured the project in the past two weeks, and Dwivedi’s goal is to have 10 of the company’s systems installed in Alaska communities by the end of 2025. 

The state, he said, offers a perfect proving ground, and a key market for Cache, with its harsh climate and big seasonal wind and solar variations.

“It’s not like we are dabbling in 15 markets and Alaska happens to be one of them,” said Dwivedi, who recently finished his seventh trip to the state in the past three months. “Alaska is the focus.”

The electric utility in Kotzebue, just above the Arctic Circle in Northwest Alaska, is set to test Cache’s system next summer, according to Tom Atkinson, the utility’s general manager.

Kotzebue previously found ample uses for excess heat from its diesel power generators — like keeping its plant and community water mains from freezing in winter. But it’s now using those diesel generators less as it integrates more wind and solar power into the grid, meaning that the community could benefit from other sources of warmth to keep its water mains thawed, Atkinson said.

The heat generated by Cache’s system could help with that problem, he said, and the technology also could theoretically absorb extra solar power in the Arctic summer for use in winter when there’s dramatically less sunlight.

“Renewable energy has worked well,” Atkinson said. “But wind and solar and batteries have only gotten us so far. Now we have to figure out other systems that will take us further.”

Nathaniel Herz welcomes tips at natherz@gmail.com or (907) 793-0312. This article was originally published in Northern Journal, a newsletter from Herz. Subscribe at this link.