Thermal energy: can the MGA fill a battery void?
A new approach to using latent heat fusion promises a versatile and cost-effective method of storing renewable energy and filling a technology gap in batteries.
A frequent criticism of renewable energy sources such as solar or wind power is that of reliability. “What happens when the sun doesn’t shine or the wind stops blowing? »
The answer is, of course, batteries.
But what kind of batteries? Lithium-ion electric batteries are an obvious solution: easy to charge, quick to ignite, and with enough storage capacity to last up to four hours of continuous discharge. Hydrogen electrolyzers, powered by renewable electricity, offer long-term storage options, as does pumped hydroelectricity.
Which leaves a middle ground missing.
Medium-term storage, covering a period ranging from more than four hours to a few weeks, is considered essential to provide electricity during evening and morning peak periods when solar production is at a minimum.
Thermal energy storage (TES) has received a lot of attention as a potential solution.
Essentially, TES uses abundant renewable energy during the day to heat a large amount of material, releasing the energy when needed as the block cools overnight.
But to capture the maximum amount of energy, thermal battery researchers have sought to apply the well-known principle of latent heat of fusion.
So what is a latent heat of fusion battery?
Well, anyone who has rushed to make ice to cool a drink has observed the principle of MGA Thermal’s new battery design.
Making ice in a home refrigerator takes time.
Energy must be removed from the water to lower its temperature to freezing point. But this is only the beginning, because even more energy must be given up by the liquid to enable its transformation into a solid.
This last amount of energy is known as the latent heat of fusion.
The latent heat of fusion released by turning 10g of water into a small ice cube would be enough to power an old-fashioned 100-watt light bulb for more than 30 seconds.
With the help of $1.27 million in funding from ARENA, MGA Thermal plans to apply this same principle roughly the size of a shipping container, using 5,000 graphite blocks. with aluminum alloy grains scattered everywhere; a proprietary medium known as Miscible Gap Alloy (MGA).
Instead of ice cubes, consider large chocolate muffins with lots of gooey chocolate chips. And instead of ice melting at 0 degrees C, the alloy works between 400 and 700 degrees C.
Cheap and versatile
Since graphite blocks are cheap and good conductors of heat, and the unit operates at high temperatures, it is both an inexpensive and efficient storage system.
Renewable energy will be used to heat the blocks to their upper operating temperatures, melt the embedded aluminum alloy and store its latent heat of fusion.
A heat exchanger system, typically using water/steam, allows distributed thermal energy to be used directly in an industrial process or to heat large-scale commercial or residential spaces, such as apartment buildings .
Potentially, the steam could be used to drive a turbine generator and generate electricity.
On a very large scale, it may even be possible to reuse decommissioned fossil fuel turbines to be powered by battery-generated steam. This would effectively mean that a large number of MGA thermal units could act as a grid-scale energy storage facility.
Demonstration and scalability
Alex Post, CTO of MGA Thermal, said, “We are working with the Long Duration Energy Storage Council to examine use cases in industrial process steam supply, agricultural heating, integrated industrial centers in low emissions and utility power generation.
MGA Thermal initially plans to build a 0.5 MW / 5 MWh demonstration system. Enough energy, if fully converted to electricity, to power a neighborhood of over 600 homes for 10 hours.
Production of the first 5,000 thermal blocks is expected to be completed over 12 weeks until mid-October 2022.
Arden Jarrett, Business Development Manager, MGA Thermal, said, “This ARENA-supported pilot project is an important milestone for MGA Thermal.
“Once completed, it will allow us to demonstrate how our technology can support the energy transition across multiple use cases and applications, and the operational data will drive our continued business growth, helping us meet the needs of our customers in Australia and abroad,” she said.
ARENA CEO Darren Miller said MGA Thermal’s unique technology has enormous potential to support the adoption of renewable energy.
“The electrical transition is going to require a variety of short, medium and long-term storage technologies,” Miller said.
“With potential deployments for industrial heating end uses, MGA Thermal could play a huge role in decarbonizing the power grid and heavy industry.”