This is a slightly crazy system which combines a HeatPump and eusocial insect. These are insects like bees, ants or termites which live in a nest structure normally as a enormous extended family.
These insects use Energy generated by PhotoSynthesis often in Woodland or RainForest. The enormous areas of Woodland in the world offer a potentially huge EnergySource.
As well as systems like EnvironmentalSlashAndBurn, a EusocialInsectHeatPump is a mechanism for extrating this Energy. As well as being entirely Renewable, the EusocialInsectHeatPump is potentially very environmentally friendly, being fairly invisible.
The basic idea is this: the nest structure of a eusocial insect can contain a very large number of individuals, which produce quite a lot of heat. A bee hive, for example, can produce 1kW of heat quite easily. Why not stick a HeatPump onto the bee hive? If this were a solid state HeatPump it should be able to run for a long time without maintainance.
The Energy from this system has to be recovered in some way. For a bee hive, there probably isn't enough Energy to make it worth while, unless you are near an Electricity system into which they could be directly plugged. However, for some of the termite mounds which produce a lot more Energy, if you strung together 4 or 5, seperated by a couple of hundred metres, you might power an Electrolysis system, releasing its power to a HydrogenBalloonNetwork. If the system can also gather the water that it needs from the wild, then it could run autonomously for a couple of years, releasing a new balloon every month or so.
This type of system would require a lot of ecological work. Ideally, you would not want to introduce insects which were not already present in the area. A system would have to be investigated to get these insects to nest around the HeatPump (in the same way that bees end up nesting in artifical hives). This is not necessarily as daft as it sounds; termite mounds have the primary purpose of ventilating and cooling the colony; a HeatPump could actually increase the efficiency of a mound. All of the components would have to be resistant to all the natural problems of the environment: animals trying to eat the inserts; insects trying to eat the wires. Finally, the system would probably only work for a part of the year, at least in temperate climates. But it should be possible to integrate within even the most delicate of ecosystems, producing much less damage or ugliness than EnvironmentalSlashAndBurn.