Although you can make it yourself following the instructions in the Energetic Forum blog posts, I decided to shell out $250 and get the kit as per http://teslachargers.com/crystallightkit.html.  You can generate electricity by connecting a wire between two different metals (leading to the oxidation and decay of the metals) this is theoretically different – the copper hemisphere is heated through several colour changes until it becomes a semiconductor, and the crystals between it and the centre electrode supposedly act as ion channels with current flowing once water is added, theoretically by pulling electrons/ions out of the water and not leading to metal decay.

Whilst I can’t confirm whether this is the case, I can confirm that the light kit has several interesting properties:

1) If you let it dry out, there is definitely not current flow or power.
2) Once it has dried out, all you need to do to get it working is to add a few teaspoons of water to the crystals (which makes an interesting noise, kind of a crunchy hiss)
3) Once you have added the water, the LED is quite bright – enough to read a book by in the dark (although in a fairly small area)
4) The light keeps on going for DAYS after you add the water – basically until that amount of water would evaporate by itself if you left it in a bowl in the open air.  Maybe even longer.  The light also doesn’t go out suddenly – it gradually fades, showing there isn’t some cut-off point; just a gradual drying and gradual reduction in current along with it.

When I can get the thing uploaded this posting will have attached a video showing me adding water to the light after not having touched it for months (since end 2013); I added water on the 30th March at 6.40pm.  I’ll update this post sometime later & say how long it lasted – based on previous experiments it’ll probably be the better part of a week, which is impressive in and of itself – a lot of output for a very little water.

UPDATE: After several failed attempts I’ve given up trying to load the video to this site, despite it being only 17MB & the site meant to handle 32MB.  Instead I’ve uploaded it to YouTube – you can view the video at

UPDATE: The LED stayed bright enough to read by for 2 days; after 3 days you could still see it glowing but only very faintly.  It lasted a lot longer in the past (although 2 days is quite impressive), not sure if this is because it’s been relatively hot lately and as such the water could have evaporated faster than before.