Re: This looks like it ends the 'need' for nukes
Nope, but it's an excellent use case for SMRs (Small Modular Reactors).
Problem is again clueless politicians and the lack of any coherent energy policy, plus some physics.
So Scandanavia and some other cities had been smart, and built district heating systems. So 'waste' heat from mostly generation gets piped to nearby residences or businesses.
The sandcastle's snag is it doesn't store waste heat. It would have to take perfectly good electricity, convert that to heat, keep the sand heated to the necessary temperature, and then transfer heat from the sand to water or whatever working fluid. So it's going to be pretty inefficient. Plus expensive, depending on the input cost of it's electricity.
Most electricity generating solutions like coal, gas and nuclear generate heat, or use water cooling. Unless that waste heat is coupled to a district or industrial/commercial heating solution (eg greenhouses), the heat energy is wasted. SMRs might be around 500MW thermal, so smaller kettles than 1GW+ big reactors. Heat produces steam, steam drives turbines, steam's condensed and cooled, then dumped or recirculated.
Given SMRs are compact compared to traditional reactors, they could be built close to demand centres, ie towns & cities. Ecofreaks would try to stop this by supergluing themselves to stuff and being generally annoying. But there's a proposal to simplify planning consent for clean energy. SMRs are clean (ie carbon free) energy, so might be possible to get planning consent and approvals faster.
But the UK's policies have rarely been integrated. So we've never really been into district heating, which is a shame because trying to retrofit the pipework & plumbing into existing housing stock would be expensive and a PITA. Plus if it's distributed as high pressure steam, it's also rather corrosive and dangeroues. I had fun once wandering around a utilidor in NY with steam pipes in it. My guide went ahead waving a long taper. If bits fell off the taper, it was probably a steam leak, and a pinhole leak would really ruin your PPE and day if you wandered into it.
But it could be a perfect solution for a NewTown, or large housing development. Plonk down an SMR, run the heating infrastructure while the project's being developed, and residents would potentially get free/cheap heating. Downside is there's no incentives for housing developers to do this, even though it would be something to help justify rip-off 'service charges', or ground rents to leaseholders.
Ecofreak Greens would naturally object because nuclear. Even though their beloved solar panels are really nuclear powered..
I tried a similar proposal with a new housing development in Reading. It was built just across from the Council dump on an old sewage works. We proposed building a CHP incineration plant to provide heat & power to the development. We calculated there'd be enough fuel (ie rubbish) produced by the housing estate to provide a good amount of the development's heat & power. Council didn't like the idea because they'd been sold that recycling means wasting energy to turn rubbish into stuff people don't want. Developer was somewhat interested, if we could pay for the plumbing, and give them a cut of the revenues. Kinda tricky given we wanted to set the CHP Co. up as a non-profit.
But such is politics. A NewTown would be perfect given the potential of SMR + CHP to make it self-sufficient in power and heat, and of course reduce it's environmental footprint by producing less waste. Sadly there's a lack of joined-up thinking between government departments that make stuff like this a bureaucratic nightmare to actually implement.