I've done a similar setup, but using Ice Boxes. In both cases though, you'll need a water chiller powerful enough to cool the water, a remote resevoir, a pump, lines going to and from the light, and the capacity to deal with the resultant heat from the chiller. I like the concept, but I'm not really sure how much energy you'd save with needing all that stuff. If you live in a really hot area most of the year though, it might just be the way to go for you. When working properly, it has the ability to get a 1000W HID really close to the plants which is pretty amazing.