> The sand itself will also be sustainably sourced – it’ll consist of crushed soapstone, which is a manufacturing byproduct of another local industry.
The requirement is not really construction grade sand but any substance with a largish thermal mass. Sand/dirt/crushed rock, etc. whatever you have right on your doorstep. There have been plenty of prototypes using such various materials as thermal mass.
All you need is a big container, some insulation to keep the heat in and lots of mass in whatever form. And some pipes to get heat in and out via e.g. water. The bigger the container, the smaller its surface area is relative to its volume. So these things can be quite efficient. If you make them large enough, you can store enough energy in the summer to last for months during the winter.
Awesome and very simple. There is a small community of eco housing that uses this system, in Boekel. They use solar panels in summer to heat the battery which lasts all winter.
On a diy scale, there is also this system for passive greenhouse called a climate battery which uses the same principle, storing heat underground and using it in winter. With almost zero energy we can use it to grow bananas in a greenhouse in the Netherlands.
The requirement is not really construction grade sand but any substance with a largish thermal mass. Sand/dirt/crushed rock, etc. whatever you have right on your doorstep. There have been plenty of prototypes using such various materials as thermal mass.
All you need is a big container, some insulation to keep the heat in and lots of mass in whatever form. And some pipes to get heat in and out via e.g. water. The bigger the container, the smaller its surface area is relative to its volume. So these things can be quite efficient. If you make them large enough, you can store enough energy in the summer to last for months during the winter.
Here's a story about a Dutch retiree who built a prototype using basalt as the thermal mass in his backyard: https://deepresource.wordpress.com/2020/03/08/cesar-seasonal...