creative use of microbes.
The idea of using microbes for energy isn't completely new. There are efforts underway to breed bacteria that can produce the chemical precursors to gasoline and other fuels.
What's perhaps a bit more interesting is the possibility that toady's deposits of oil and natural gas were originally produced by bacteria.
Extremophiles that exploit extreme environments under the earth's crust where temperatures and pressures are high are only a tiny part of the story of underground bacteria. It turns out that there is a vast web of microbial life underground; some of them exploit food sources, such as radioactivity, which are completely unconventional from our own point of view. Microbes go everywhere; the estimated total mass of bacteria on earth probably exceeds that of all other life forms. That is to say, they not only outnumber us; they weigh more.
All that biomass, as it reproduces and dies, creates huge reservoirs of organic waste under the surface of the planet, which creates a fertile zone for the growth of more, new bacteria that feed on that waste; and gases, secreted in microscopic but relentless amounts, are an ordinary, day to day by-product of bacterial action. Cow farts, rich in methane (and a possible major contributor to global warming gases) are just one odiferous example of this. So the bacteria under the surface of the planet are undoubtedly one of the generators of natural gas.
More intriguing, perhaps, is the possibility that oil deposits may be linked to bacterial action. There is simply so much oil in many deposits, and in so many different places, that the question of whether its presence can all really be ascribed to the burial and decomposition of ancient plant material has been raised. It may be that the oil we pump today is actually bacterial waste of one kind or another. If so, oil may be, to some extent, a renewable resource; although the time frame in which it's renewed is probably measured on the long time scale.
Life exists so far under the surface of our planet that it suggests it could easily exist under the surface of other planets whose surfaces appear, at first glance, the be hostile to life. Life may have originally evolved under the surface of the planet... ours or another's... conditions there may have been more favorable, earlier, than they were on the planet's surface, and more stable.
The ability of microbes to decay things certainly comes in handy. Creatures that eat dead life, both plants and animals, have specifically evolved to feed on those sources, and they are a vital part of the food chain. Without them, the nutrients that are locked up in the various complex chemical structures that bodies are composed of would remain unavailable for further use.