The idea of this was to develop a low cost and easily deployable module, that is made from easily obtainable off the shelf parts. I have seen similar use of peltier/teg devices to generate power, this particular project has the main goal of standardizing a module, which makes it much easier to scale to ones needs.
Benefit of a TEG being it can be used to generate electricity 24x7 utilizing temperature differentials. Similar technology is used in the space industry for probes and satellites so it seems to be a fairly reliable solution.
Possible sources could be Solar thermal, Geo thermal, furnace, fire, or any wasted heat source.
In addition to the basic use of aluminum water blocks and teg modules, I think there needs to also be a focus on developing either a discrete circuit or micro-controller based solution to maximize power harvesting.