Nuclear fusion is the holy grail of scientists (and politicians) as it could produce limitless free energy without nasty consequences like meltdowns and radioactive waste. Though nobodys been able to build a reactor that produces more energy than it consumes (except arguably one time), scientists are still trying, with three experimental reactors currently in operation in the US. One of those, however, has been in the Obama administrations cross-hairs: MITs Alcator C-Mod reactor.