"World's first working thermal battery" promises cheap, eco-friendly, grid-scalable energy storage

South Australia has recently put the world's biggest lithium battery into operation – but perhaps it should've waited. A local startup says it's built the world's first working thermal battery, a device with a lifetime of at least 20 years that can store six times more energy than lithium-ion batteries per volume, for 60-80 percent of the price.

Climate Change Technologies, also known as CCT Energy Storage, has launched its TED (Thermal Energy Device) with a set of remarkable claims. TED is a modular energy storage unit that accepts any kind of electricity – solar, wind, fossil fuel-generated or straight off the grid – and uses it to heat up and melt silicon in a heavily insulated chamber. Whenever that energy is required, it's pulled out with a heat engine. A standard TED box holds 1.2 megawatt-hours of energy, with all input and output electronics on board, and fits easily into a 20-ft (6-m) container.

Here are some of CCT's banner claims about the TED: For a given size volume, it can store more than 12 times more energy than a lead-acid battery, and several times more than lithium-ion solutions. Installations can scale from 5-kilowatt applications out to a virtually unlimited size. Hundreds of megawatts of instantly accessible, easily controllable power should be no problem – all you need to do is add more units, plug-and-play style. In the case of an outage, each TED device can remain active for about 48 hours.

It can also charge and discharge at the same time, and there are only three moving parts per box, so maintenance is almost negligible. Where lithium-ion and other batteries degrade over time, perhaps dropping to 80 percent capacity in some 5,000 cycles or so, the TED system has shown no signs of degrading after 3,000 cycles of service on the test bench, and CCT's CEO Serge Bondarenko tells us over the phone that the company expects its units to last at least 20 years.

"Molten silicon just doesn't degrade like lithium does," says Bondarenko. "That's a chemical process, ours is simply phase-change with heat. In fact, it appears silicon even gets better at storing heat after each cycle. And if you do need to decommission a TED device, it's 100 percent recyclable. It simply doesn't create the environmental problems that lithium does."

Importantly for any large scale usage, it's cost competitive – Bondarenko projects it'll cost some 60-80 percent of the price you'd pay for an equivalent lithium-ion solution like Tesla's Powerpacks, while taking up a smaller footprint on the ground. TED can easily be adapted for earthquake-prone environments by installing it on a quake-proof platform, but in the event of a serious issue, Bondarenko tells us "we just turn it off, and it cools down until it's ready to go again. It's very safe." Mind you, since the melting point of silicon is more than 1,400° C (2,550° F), it's not something you'll want dribbling out on the ground.

CCT has signed an initial deal to provide TED devices to Stillmark Telecommunications, as well as a reciprocal manufacturing agreement with MIBA group, which will have exclusive rights to manufacture and sell the technology through Denmark, Sweden and the Netherlands, with negotiations ongoing about adding other European countries to that list. Manufacture is set to begin this quarter, and Bondarenko says once the devices have been proven commercially, the company plans to ramp up rapidly and be ready to build 100-megawatt-plus installations within a couple of years.

Obviously, this seems like great news for the renewable energy sector. Wind, solar, tidal and other renewable energy technologies can be very effective at generating a lot of power, but only when it's available rather than on demand. Grid-level energy storage solutions could store energy up during the solar peak of the midday heat, then return that power to the grid during peak load times in the evening when the sun's not shining, making renewables a truly 24-hour energy source.

Could the system's huge energy density also scale downward to power electric vehicles? "No," says Bondarenko, "it's too big. The container, the insulation, the heat engine, it needs to be a certain size to realize its density benefits. But we can certainly charge electric vehicles, and we have been in discussions with some manufacturers of large electric ferry boats that could charge the battery up at the dock and use it to power their ferries."

If things pan out the way CCT believes they should, this cheap, high-density thermal battery, powered by abundant elements and totally recyclable, could be a key technology in helping move the world toward a clean energy future.

Source: CCT Technologies