EATR – the energetically autonomous tactical rover – gets its energy on the battlefield from damn near anything, even dead bodies. It doesn’t exist yet, but the U.S. government has contracted a Maryland-based company to develop this combat for field operations. The company says of their gruesome device:

[The EATR] can find, ingest, and extract energy from biomass in the environment (and other organically-based energy sources), as well as use conventional and alternative fuels (such as gasoline, heavy fuel, kerosene, diesel, propane, coal, cooking oil, and solar) when suitable.

Basically, the robot would just roam on its own for potentially years while it was fueled by whatever it came across.  This has applications in surveillance, health care, but most terrifyingly, military offensives.

Fox News rightfully points out that this type of engine could be extended to create “mobile gunships.”  If that happens, we’ll have robots programmed to collect organic material (like you) in order to keep running.  They’ll also have guns.  If that’s not a recipe for a sentient Skynet, we don’t know what is.