Super-hot salt could be coming to a battery near you

Super-hot salt could be coming to a battery near you thumbnail

There’s a lot happening in the climate world. In the US, election workers are still counting votes and counting them again to determine control of Congress. At the UN climate conference, delegates are negotiating, fighting over climate targets, and negotiating finance agreements.

We are still waiting to hear more about these crucial moments for the future climate policy and technology. While I am still waiting for more information, I will keep my ears open for more concrete insights. Let’s stop speculating and get into the details about something I believe we should all be discussing more: batteries.

I’m obsessed with batteries, and I’m always watching the wave of alternative chemistries that’s slowly percolating into the growing energy storage market. Although some of these new players may be cheaper than the industry-standard lithium ion batteries in the long-term, they face significant barriers to adoption. Let’s take a look on one startup’s quest to store energy using superhot salt.

Why we need new batteries

The world is building more capacity for renewables, especially solar and wind power that come and go with the weather. We need to be able store energy. (I went more into this a couple weeks ago in the newsletter, check that out here if you missed it. )

Pumped hydropower accounted for over 90% of worldwide energy storage as of 2020. Although hydropower is an inexpensive and efficient way to store power it has major environmental issues and restrictions on where it can installed. It requires large amounts of water.

Batteries make up the majority of today’s energy storage and will likely be the main driver of future energy storage market growth. Lithium-ion batteries are the most common today, and they are similar to those in your smartphone or electric car.

After decades of development, scaling, and cost cutting, lithium-ion batteries are now cheaper and more efficient. New battery Gigafactories are popping up around the globe almost every other week.

But there are some mismatches between the strengths of lithium-ion and what’s required in batteries used to store stationary energy.

  • Price: Grid-scale storage needs to be dirt-cheap to help renewables be affordable. Last year, the US Department of Energy set a goal of reducing costs by 90% by 2030. Although lithium-ion batteries have become cheaper over the years, there are still potential material shortages that could cause them to be less affordable.
  • Size: Lithium-ion batteries pack a lot of power into a small space. While battery size is important for devices like phones and cars it’s not as important for grid-scale energy storage. Lower energy density could translate into lower costs for stationary applications.
  • Lifetime: Industrial plants often put in equipment that, when maintained, lasts for decades. Lithium-ion batteries typically need to be replaced every 5-10 years, which can be pricey.

How hot salt can help

With the mismatch between lithium-ion batteries and our future energy storage needs, it seems like everybody is working on an alternative way to store energy. In just the last year, I’ve covered iron air and iron flow batteries, plastic ones, and even one startup using compressed carbon dioxide to store energy.

Now, another technology is making its way from the lab into the commercial world: molten sodium.

Ambri is a Boston-area startup that’s building molten-salt batteries from calcium and antimony. The company recently announced a demonstration project deploying energy storage for Microsoft data centers, and last year it raised over $140 million to build its manufacturing capacity.

The company says its technology could be 30-50% cheaper over its lifetime than an equivalent lithium-ion system. Molten salt batteries can also exceed 80% efficiency, meaning that a relatively low amount of energy that’s used to charge the battery is lost to heat.

Ambri was founded in 2010 based on research from Donald Sadoway’s lab at MIT. David Bradwell, founder and chief technology officer of Ambri, stated that the goal was to create a low-cost product suitable for stationary storage.

The inspiration came from an unlikely source: aluminum production. The team created a low-cost, lab-scale energy storage system using chemical reactions similar to those used for aluminum smelting. However, this idea has not been easy to make a product.

The magnesium- and antimony-based chemistry that the company started with proved difficult to produce. In 2015, after continuing issues with the batteries’ seals, Ambri laid off a quarter of its staff and went back to the drawing board.

In 2017, the company pivoted to a new approach for its batteries, using calcium and antimony. Bradwell states that the new chemistry is based on cheaper materials and should be easier to make. The company has made progress since the pivot. It has also worked out technical issues and gone through third-party safety testing. The company has also signed its first commercial deals, including one with Microsoft.

The Microsoft energy storage system. Image courtesy Ambri.

There are still major challenges ahead for the startup. The batteries operate at high temperatures, over 500degC (about 900degF), which limits what materials can be used to make them. Moving from single battery cells that are roughly the size of a lunchbox to large containers-sized systems can pose logistical and system control challenges.

Deploying a product in the real world requires “dealing with real-world things that happen,” Bradwell says. A new battery system can be thrown off-balance by everything from lightning strikes to rodents.

At least one thing has changed over the last decade though: the market. Bradwell says that investors and casual observers used to be resistant to the idea of energy storage. The question now is how fast the industry can grow.

It will take time for Ambri, and other new battery outfits, to scale manufacturing and prove they are a viable, affordable option to existing batteries. As Bradwell says, “the journey continues.”

Keeping up with Climate

Disagreements about climate goals are hanging over COP27, the UN climate conference. Some leaders want to reiterate the need to keep the temperature at 1.5 degrees Celsius, even though the target seems out of reach. (New York Times)

Delegates at COP27 are still deep in talks over loss and damage funding for climate change impacts. (Bloomberg)

– If you missed it, check out last week’s newsletter for more on why this funding is at the center of the talks.

The US is working to cut the influence of China in climate tech manufacturing. But the move could make some technologies more expensive and slow progress on climate goals (Grid News)

– In the meantime, the US is relaunching climate talks . (Washington Post)

Republican gains in the US midterms were limited, quelling some renewable energy advocates’ concerns that Congress would dismantle recent climate action. (Inside Climate News)

The electric revolution has two wheels. About 40% of motorcycles and other smaller vehicles sold last year were electric, a much higher fraction than larger passenger vehicles. (Protocol)

We’re getting a better idea of AI’s climate impacts. Researchers have developed a new method to understand the emissions from large language models ,, which require a lot of energy to train and run. (MIT Technology Review)

Organic solar cells are getting better. This technology could open new opportunities for solar. However, organic cells are light and flexible and will need to be durable and easily-manufactured in order to succeed in the market. (Science)

Electric trucks are coming, bringing with them wild requirements for the grid. By 2035, a truckstop could require as much power as a small town. (Bloomberg)

Grids may be able to handle fleets of short-haul delivery trucks, but long-range trucking poses a greater challenge. (MIT Technology Review)

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