Are thermal batteries an alternative to lithium-ion?

By Dominic Ellis
Arizona State University research for Swedish cleantech company Texel found thermal cheaper than lithium-ion in the US market

Even those with a passing interest in the energy industry would have heard of lithium-ion batteries, seen by many as the solution for powering the electric vehicle battery revolution. But there may be less well-known and potentially more effective alternative in thermal batteries.

The basic principle of thermal battery is simple. Electric resistance coils heat an inexpensive thermal storage medium (silica sand) using low-cost excess electricity, such as intermittent solar and wind power sources.

Energy is stored as ultra-high temperature heat (up to 1000℃/1850℉) – at a fraction of the cost of batteries. Whenever needed, a specialised turbine reconverts the heat to electricity. An innovative turbine can do this without combustion, as atmospheric-pressure air is passed through the “Thermal Storage” and drives the “Turbine” to generate electricity.

By adding a combustor, the battery can also produce even more dispatchable backup power, ideally using an emission-free fuel such as green hydrogen in the combustion process. This is also how the battery can provide spinning reserves.

Thermal's prospects have recently been enhanced by a new study from Arizona State University (ASU), which evaluated market opportunities for Swedish cleantech company TEXEL Energy Storage and found TEXEL offers a lower cost to lithium-ion batteries for the American market.

The study shows TEXEL's technology could be successful in California and suggests the company pursue all customer segments of the California market for coupled storage and generation applications, where TEXEL's technology, paired with solar PV, costs at average of 8 cents per kWh (5 cents incl. thermal) compared to 14 cents per kWh for solar PV and lithium-ion for large commercial and industrial-scale applications.

In New York, price differences between off-peak and on-peak energy rates are sufficiently great enough to create an opportunity for using TEXEL in residential and commercial markets when considering storage arbitrage – essentially charging batteries with low grid prices and discharging batteries to avoid higher, on-peak grid prices. For example, TEXEL can yield a delivered residential average electricity cost at 7 cents per kWh compared to lithium-ion at 14 cents per kWh.

Also, the report highlights an opportunity for the Power Purchase Agreement (PPA) market with coupled storage and generation. A recent 4-hour lithium-ion storage plus solar PPA yielded a blended cost of $43 per MWh compared to a $26 per MWh cost that could be possible with a 4-hour TEXEL plus solar PPA.

Lars Jacobsson, Founder and CEO of Swedish cleantech company Texel Energy Storage - which intends to manufacture the technology in the US - said the ASU study shows that TEXEL has a great opportunity in the American market and has "the right focus" in targeting California. "It also shows that our technology is a hugely competitive alternative to existing energy storage technologies, such as lithium-ion batteries. An economically viable and circular energy storage technology is needed to be able to create the change in future energy production and distribution and to reach future goals and legislation in states like California."

TEXEL metal hydride thermochemical energy storage technology provides an emerging solution that can store energy and provide both electrical and thermal output. Furthermore, the TEXEL storage chemistry is made from environmentally benign chemicals which are stable for long durations and have expected life cycles of 40 years.

These chemicals can be salvaged and recycled, which helps creates a circular market mechanism to reduce environmental impact compared to single-life batteries that have little to no recycling. In addition, the salvage value at the end of cycling life enhances project economics by recovering a portion of the capital investment.

"The transition to a low-carbon, sustainable energy system, and evolution to a zero-carbon future, will require ultra-low-cost storage manufactured from environmentally benign materials that are stable for long durations without degradation and energy loss and are recyclable and circular. TEXEL's storage technology provides an emerging solution, which not only stores energy but can provide both electrical and thermal output," said ASU Associate Professor Nathan Johnson, Director of the Laboratory for Energy And Power Solutions (LEAPS) and primary investigator for the study.

The study's findings also indicate opportunities for TEXEL to provide cost-competitive, sustainable, and reliable power to other regions.

The electric vehicle (EV) market is growing rapidly and has even proved resilient to COVID-19 related shutdowns, seeing year-on-year growth throughout 2020, which in turn is sparking major innovation in the batteries sector.

Battery Resourcers, a vertically integrated lithium-ion battery recycling and manufacturing company, recently announced an agreement with American Honda Motor Co. to recycle Honda & Acura Electric Vehicles (EV) batteries. Honda's batteries will initially be processed by the company's recently expanded site in Worcester, Mass. and later at a new commercial scale plant that will be operational in the spring of 2022. The new site which will be capable of processing more than 20 million pounds of batteries.

Albemarle Corporation has opened its Battery Materials Innovation Center (BMIC) located at its Kings Mountain, North Carolina, site. It is expected to be fully operational this month and will support Albemarle's lithium hydroxide, lithium carbonate and advanced energy storage materials growth platforms. It has been equipped to enable synthesis of new materials, material properties characterisation and analysis, material scale-up capabilities, and material integration into battery cells for performance testing.

Comau has developed a high-volume module manufacturing line  to produce new generation lithium-ion batteries for Leclanché, a leading global provider of energy storage solutions for the heavy transport, naval and railway industries. The highly automated line is the result of a simultaneous engineering process and combines industrial robots, vision systems, laser welding, and the automated in-line validation of joints via AI.

It will allow Leclanché to produce up to six times the company’s current capacity, reaching an output of more than 60,000 modules per year. The solution is also expected to reduce costs by up to 20%, support 50 different product configurations and save Leclanché valuable time when introducing new formats into the manufacturing line.

In May, a new battery from 247Solar Inc., a spinoff of MIT, was unveiled - operating like an electrochemical battery but with significant advantages at longer durations. It is designed to replace traditional diesel gensets at remote mines, and the company claims it provides 24/7 highly reliable operation with higher renewables penetration, significant fuel savings, and dramatically lower lifetime operating costs.

The IEA has set an ambition for 30% of the world’s road fleet to electrify by 2030. This translates to 44 million EVs, a mobility revolution which will need to be powered by approximately 220 billion lithium-ion battery cells. But as manufacturers strive for sustainable efficiencies, thermal batteries may also have their place.

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