Thermal “muffins” store much more than fat

When you think thermal energy storage, you might not think choc-chip muffin.

That’s the example MGA Thermal has used to describe a new type of energy storage material that combines a metal alloy, graphite, and one or two secret ingredients.

The mixture comes together in a block that looks a lot like a Besser Block. It can be used to repurpose thermal power stations, or store energy at solar or wind farms for hours or days.

MGA Thermal expects the first Miscibility Gap Alloy (MGA) blocks to be in commercial production early in 2023, and hopes to have its 5 MWh demonstration-scale thermal energy storage system pilot completed at a factory in Tomago in the Hunter region of New South Wales at about the same time.

It is a skyrocketing trajectory for technology that was born at the University of Newcastle less than a decade ago.

MGA Thermal marketing manager Arden Jarrett says the company is already looking to scale-up production every 12-18 months, from 1000 bricks per day in early 2023, to 10,000 the following year, and 100,000 a year or two after that.

It is a skyrocketing trajectory for technology that was born at the University of Newcastle less than a decade ago. Erich Kisi, a Professor of Material Science, and Alex Post, who holds a PhD in concentrated solar thermal power with the CSIRO and has been named among the country’s top innovators, put their minds to the problem of making concentrated solar power more efficient.

They decided the greatest need was a new form of energy storage, and set about cooking a choc-chip muffin with a difference.

The muffin analogy, Jarrett says, comes from the fact that particles of metal alloy within the brick melt like chocolate chips when heated to about 750 degrees, while the graphite block remains solid.

The 20cm x 30cm x 16cm blocks – a Lego-type solution to thermal energy storage – can store a huge amount of energy as heat. They are recyclable and non-toxic.

The paper Miscibility Gap Alloys – A New Thermal Energy Storage Solution, written in 2017 by University of Newcastle researchers including Kisi and Post, stated Miscilibity Gap Alloys “demonstrated excellent characteristics for thermal storage applications over a wide range of temperatures”.

“…particles of metal alloy within the brick melt like chocolate chips when heated to about 750 degrees, while the graphite block remains solid.”

Arden Jarrett

“Heat can be delivered rapidly due to very high thermal conductivity leading to modular solid storage designs which can act as solar boilers for direct steam CSP [concentrated solar power] or other applications,” the paper notes.

The commercial potential of the technology led to the formation of MGA Thermal, with Erich Kisi as CEO and Alex Post as the Chief Technology Officer. The company now employs about 30 staff.

In August this year (2022), the Australian Renewable Energy Agency (ARENA) announced funding of $1.27 million for MGA Thermal towards a medium duration thermal energy storage demonstrator. This pilot unit is under construction at the Tomago factory to demonstrate the generation of steam from stored thermal energy.

It will have a storage capacity of 5MWh and will demonstrate charging and discharging of up to 500kW.

ARENA CEO Darren Miller said MGA Thermal’s unique technology was a research breakthrough with “enormous potential to support the uptake of renewable energy”.

“The electricity transition is going to require a variety of storage technologies that are able to discharge over a range of timeframes from hours to days,” Miller said.

“MGA Thermal’s novel approach could make a real difference in the medium and longer-term storage category, supporting hydrogen and pumped hydro.

“With potential deployments for industrial heating end uses, MGA Thermal could play a valuable role in decarbonising both the electricity grid and heavy industry, which often requires high temperature heat and steam for their manufacturing needs.”

Electricity giant AGL Energy Limited has also declared interest in the technology with a $1 million feasibility study of its application to the 200MW Torrens Island B power station in South Australia, supported by ARENA.

“The electricity transition is going to require a variety of storage technologies that are able to discharge over a range of timeframes from hours to days.”

Darren Miller

The study includes both MGA technology and that of German company Kraftblock.

AGL will research whether a thermal battery can power a 200MW generating unit at the power station for eight hours, and has said if the study is successful, “large manufacturers may also be able to use thermal batteries to decarbonise industrial processes requiring heat”.

The Australian Energy Market Operator has said more than 60GW of dispatchable energy generation and storage will be needed by 2050 to support the uptake of renewable energy, with the most pressing need in the medium-duration (4-12 hours) storage area to manage the variable output of wind and solar.

Medium-duration storage, MGA Thermal says, is its goal.

“Our primary focus is enabling intermittent renewable energy sources, such as the sun and wind, to provide base load electricity to the grid, and process heat to industry,” its website says.

Marketing manager Arden Jarrett says there is significant interest from an industry that is traditionally cautious.

“We’ve got a lot of conversations in progress, particularly in repurposing thermal or gas power stations,” she says.

“Because the material is so dense and the ideal temperature is around 600 degrees to repurpose the steam infrastructure, we can fit within the brownfield site requirements. This means we have a bit of a leg-up when it comes to alternate energy storage in repurposing those sites.

“We’re also working with mineral processing groups to determine the feasibility of providing heat for them.

“One of the benefits of the system, apart from it already being stored in heat, is that it is essentially decoupled in terms of charging and discharging. You can charge for eight hours during the day but that discharge of heat is continuous. We don’t have the cycles that batteries have.”

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MGA Thermal says its core business is making the blocks and working with clients to ensure the system works and, Jarrett says, some of those discussions are already talking about a scale that would include multiple gigawatt hours.

The storage system is being designed to work along the short-term power of batteries.

“We’re really meeting where batteries leave off,” Jarrett says. “After half an hour or an hour with the demand met by batteries, we can store energy for hours or days. Our medium to long-duration energy storage can meet that eight-hour demand shift that’s needed to store solar and release it at night.”

The Miscibility Gap Alloy blocks can be made from recycled materials and can be recycled at the end-of-life with virtually no deterioration of the metal alloy particles of the blocks.

She says the prediction is that based on the current interest, MGA Thermal will be sold out of the blocks several years ahead.

So what are the nuts and bolts of these bricks?

The Miscibility Gap Alloy blocks can be made from recycled materials and can be recycled at the end-of-life with virtually no deterioration of the metal alloy particles of the blocks.

As the block absorbs energy, the metal alloy melts while the block remains solid. The heat is rapidly distributed. The solid to liquid change stores the energy, which is released as the block cools.

The blocks are used in thermal energy storage systems that deliver continuous high temperature heat or electricity.

Suggested applications for the technology are for industrial heat, power station retrofits, utility-scale energy storage, in conjunction with green hydrogen, solar and wind power, and concentrated solar power.

To find out more, visit the website.