I've been chatting to another user on here (https://slrpnk.net/u/JacobCoffinWrites who does the cool photobash images of solarpunk scenes) and it really got me thinking about solar concentrators so i went on a bit of a binge learning about them, there are so many really cool designs and so many things a source of heat like that can be used for.
One idea i especially like is using it to power absorption refrigeration (like off-grid gas powered refrigerators use) so when the sun is hot you can focus it's power and use it to cool your house -- then when it's starting to get cooler switch it to heating, ideally heating a medium which will retain the heat so you can distribute it through the night. For agricultural use it could heat greenhouses and drying rooms, industrially there's an endless amount of possibilities. Even recreationally it could be great, cutting out the cost of heating a pool or hot tub - could really make some off-grid luxury.
A great youtube channel with various diy examples is Sergiy Yurko, who's still managing to make great videos despite living in Ukraine - https://www.youtube.com/@sergiyyurko8668/videos
and https://www.youtube.com/@GREENPOWERSCIENCE/videos has some really cool videos too, like demonstrating using a fresnal lens to melt metal
I am investigating some components of a system to make biochar with a solar concentrator but it is slow going. My idea is to circulate molten salt through the focus zone of a double-parabola channel. This focuses heat on the target pipe for a broad range of sun angles with no tracking. I have read that a eutectic mix of sodium carbonate and potassium carbonate (aka soda ash and potash, respectively) has a melting point under 500C, and fast pyrolysis is possible with molten salt at this temperature. I am trying to find information about electromagnetic pumping (aka magnetohydrodynamic pumping, just like Red October!) but there are very few such devices sold - mainly for continuous metal casting, apparently. If molten salt could be heated by sun and fast pyrolysis could be done (which makes a larger fraction of pyrolysis oil than slower processes would do), then there would be very little emissions and very little waste heat I think. Still some steam I suppose.
oh that's really cool, would be a such a low impact way of making biochar that when you add it to the soil it'd probably actually be atmospheric carbon negative so essentially free carbon-capture - on a tiny scale but if it was how everyone did it then that's one thing pushing in the right direction instead of the wrong direction.
and interesting about the electromagnetic pumping, i don't think it's especially hard to engineer compared to stuff that's readily available in a dozen different colours so i guess there's just no perceived market for it - i'll have to read up and see if there are any DIY projects, being able to move liquid salt around would be really useful in a lot of heat transfer applications.