<story><title>US Government funds pilot project for heated sand energy storage</title><url>https://www.pv-magazine.com/2024/04/04/us-government-funds-pilot-project-for-heated-sand-energy-storage/</url></story><parent_chain></parent_chain><comment><author>retrac</author><text>Heat storage has an aspect that was counterintuitive to me, but follows from basic geometry.  It benefits greatly from large scale, since the ratio of the volume to surface area [1] decreases the larger you make a container.  Accordingly, if a heat tank is large enough, the surface area becomes negligible relative to its volume, and it, in effect, becomes well-insulated by its own mass.  For really big tanks, like might be used for an entire town to heat itself over a winter, practical self-discharge rates can be just a few % per month, which is better than most rechargeable battery technologies.&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;commons.wikimedia.org&amp;#x2F;wiki&amp;#x2F;File:Comparison_of_surface_area_vs_volume_of_shapes.svg&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;commons.wikimedia.org&amp;#x2F;wiki&amp;#x2F;File:Comparison_of_surfac...&lt;/a&gt;</text></comment>
<story><title>US Government funds pilot project for heated sand energy storage</title><url>https://www.pv-magazine.com/2024/04/04/us-government-funds-pilot-project-for-heated-sand-energy-storage/</url></story><parent_chain></parent_chain><comment><author>ejb999</author><text>I am really intrigued by using sand for energy storage - what I don&amp;#x27;t get (not my field) is given a typical 2000sf house, located in the colder part of the country as an example, how much heat could be stored for how long? i.e. is it even feasible to use solar panels to power resistance heaters all spring&amp;#x2F;summer&amp;#x2F;fall, to save up enough heat to keep a house warm for the entire winter? if so, how many panels would you need and how big a sand battery would it take.&lt;p&gt;I am not planning on doing this, but explaining it on a scale that I can relate to would be helpful, because I know, for example, that said house can store a winter&amp;#x27;s worth of heat in a 1000 gallon oil tank, or small woodshed big enough for 6 cords of wood.</text></comment>