First Molten Salt Power Plant Approved in California

I am surprised that California is letting this one fly. Don't they know salt contains Sodium and Chlorine which are both toxic and bad for the environment when released? Plus now mixed together and heated up to super hot levels, My gosh someone could get burned as well!

About 20 yrs. ago, I worked with a strange man who was promoting thermal storage in bag-like containers of sand. He had all the engineering down and even went through the patent process. Nobody bought it. It was safe, had would take any heat source and store it and release it when needed. The ideas was to convert off-peak electric power into store thermal energy and use it for home heating or convert it to mechanical energy by making steam to run a generator. It still sounds like a better idea than this one.

I have put hours of thought into a similar concept to take advantage of our wide seasonal temperature swings, -35F to +105F, provide good cooling in the summer and good heating in the winter.

I planned on just using large heat exchangers to freeze the earth in the winter around a number of thermal wells drilled around 150 -200 feet below my property in one location and use solar collectors to heat up another area of earth around another set of wells to provide the winter heat source.

The cost of all the well casings and the related plumbing and controls where surprisingly reasonable and the overall math seems to show it being a realistic and practical way to go with under a 5 year payback.

Until I contacted a well driller that is. He said he would give me price break on the drilling for the number of wells I would need and the depths I wanted. He figured around $200K for the drilling if I supplied all the materials myself. I asked him if I get to keep the drilling rig when I am done being I would be paying twice as much for a bunch of holes in the ground as what the rig he owned likely cost new 20+ years ago. That was basically the end of the discussion and the plan.

Apparently well drillers don't like it when prospective customers know what the true value of a hole in the ground is worth let alone what their machine was worth a few decades ago.

I am still watching auctions every year for an old worn out drilling rigs. They can go cheap but always need someone with good fabrication skills to rebuild them back to working condition. Or I more likely I could just build one myself someday too being it would be about the same work as rebuilding an old one.

Wow quite a plan you have there, pity about the drilling costs.

Back to the salt. Some people I know at a technology company in Brisbane were working with molten salt in conjunction with CSIRO. It can be rather difficult to work with, corrosion is the obvious issue but the hard one is the amount that the volume varies between solid and liquid. It tears things like the heat exchangers to bits. They ended up mixing graphite with it but still had problems. It would be interesting to know how this problem has been overcome.

Another idea presented was to use molten silicon due to its very high latent heat. I don't know how it progressed, silicon is damned expensive but the scheme was to use successive the remelting as a purification method and sell the purified product periodically at a good profit.

My point was, WHY use molten anyhthing?

Basically because it's "wet"

Thermal transfer rate tends to be higher as you have both convection and high surface conduction. And by facilitating movement, you refresh through mass exchange.

Molten materials utilise the huge amount of energy held as part of phase change, latent heat of solidification. It is the same sort of deal as the the latent heat of vaporisation in steam or refrigerants. Heat pumps utilise phase change too.