So the excess energy is used to warm up these blocks that in turn produce steam power that makes more excess energy?

Yes, I do understand that they are dealing with the thermal dynamics of a storage system using phase change as the storage mechanism . . . within the blocks themselves. However, there is no mention of where, or for that matter, how . . . to store these blocks, and the insulation requirements, nor for that matter the heat retention dynamics of the blocks themselves. We should have had much more information made available in this report, such as a link to the science. Much more info needed.

Chris, I think it is clear that the blocks are built to readily gain or lose heat. The normal standards would apply to keeping them insulated to retain heat. The number I'd like to see is the phase change temperature. It is a bit misleading to compare the cost to batteries, though. Batteries put out electricity, the highest form of energy - these may be medium - temperature heat, one of the lowest forms, which would be mostly lost on the way to becoming electricity.

Paleochocolate, it's about supply and demand - the system takes the energy when it's abundant and timeshifts it to when it's scarce.

I think it would be useful to state the storage time period envisaged. This project sounds like a short term maintenance period aid for a self contained power station. It would not be so critical on thermal conductivity with the brake-pad type make up of the bricks if it was for longer term storage.

reminds me of the electric storage heaters sold in the UK in the 60's. basically a block of cast iron heated electrically until it glowed cherry red during off peak hours and encased in a highly insulated shell to release the energy during the day. need to see more detail about the total system design as to how this integrates into the grid

Its what is not being said here that worries me! What isn't being said is how do you charge the Phase Change Material (PCM) blocks with 'renewable' energy? I suspect the answer is that you use excess renewable electricity as seems to be implied in the video. So 100% renewable electricity charges a PCM version of the storage heater which then releases heat to create steam to make electricity on demand with best performance around 30%, but some is lost in storage, so I'd bet no more than 25% comes back as electricity! Give me a battery or a big weight in a mineshaft any day. Clever part is getting high thermal conductivity in a PCM material.

“... surprisingly simple new energy storage system,”. Uh, no. Phase change energy storage as a concept has been around for several decades.

At first I thought this system is a way for cold plants to store heat until wind and solar aren't producing, which would obviously be no help to emissions. But if the blocks are heated with renewable electricity, so many issues remain: can the blocks be put inside existing boilers at thermal plants? If not, how much does the new thermal loop to pump supercritical steam through the blocks cost? How are they heated up, and how will that electrical system withstand super hot steam? Are these blocks better than molten salt thermal storage?

"but storage remains a major hurdle to making [renewable energy] systems viable". Solar and wind are already viable! They're the majority of new generation because they're cheap and quick. Maybe Michael Irving meant storage is needed to reach 100% RE.

I hope their engineering is better than their explaining. It appears, but is not said in so many words, that it's a phase change material embedded a thermally conductive matrix that is strong and holds its shape. Great, now you don't need vats of liquid salt or similar since it is its own container.
Then they throw in coal plants not using any fossil fuels. They are starting with a decommissioned coal plant. That makes some sense since it's already connected to the grid. So rather than the plant sending power out to the grid, it's taking it in and somehow turning that into heat to store in the blocks when there's "excess" energy available. Then in a manner similar to how a coal plant operates it uses the blocks to heat water to turn the turbines to generate electricity.
There are some claims about the cost, size, and energy storage capacity compared to a lithium battery. What I'd be interested in is the efficiency of the cycle, power into the plant compared to power out. I'd be surprised if *that* was the same as batteries.
The bonus might be in the cost to convert a functioning or retired coal plant to a usable energy storage facility. A lower efficiency might be offset, for a time, by the reduced initial outlay of converting a coal plant vs building a new Tesla battery facility. We don't see that info here, we just see a happy baby touching the block to show us it's safe.