Molten Salt Technology — Saving Solar Energy for a Rainy Day
I hope the world is paying close attention to the development of molten salt technology to store solar energy as heat, for later conversion to electricty at night and on cloudy days. As reported here by The Guardian, the Italian utility Enel just unveiled “Archimede,” apparently the first solar thermal / concentrated solar power (CSP) plant to use molten salts for heat transfer and storage.
This subject came up in detail in the interview I conducted with Dr. David Mills for the chapter on the subject in my book. It was clear to me at the time that molten salt has a long way to go if it is to scale to the extent that it will move the needle in terms of facilitating the penetration of renewables. However, this is a true breakthrough.
I only wish Sicily were in my travel plans; I’d love an excuse for a visit at this momentous occasion.
There are a number of issues pertaining to the uptake of CSP and thermal storage is one of them.
Molten salt is a clever concept and I’m sure it works well, especially at the very high temperatures generated by the so-called Power Towers. The problem, I believe, is that the salt “freezes” at around 200C so they have to incorporate gas burners all along the line to prevent a catastrophic freezing of the HTF.
Experiments are now being conducted using all sorts of materials for thermal storage. Everything from graphite and concrete blocks to coconut oil and gravel. I’m sure they will all work to some degree, but the bottom line is economics. How economical is is to install the gas system in the first place and how much is it used and at what cost?
For the record, my favourite technology is CLFR using water as the HTF and a cheap oil and gravel thermal battery, all deployed in a distributed power model on a hybrid plant.
Eric: Do you have a business interest in CSP? If you don’t, it sounds like you should; you certainly have been studying it. It’s a capital-intensive little bugger, though; isn’t it?