President Obama on Thursday visited areas recovering from hurricane Sandy, which knocked out power to more than 8 million people. Power is finally coming back on for the last few in New York and New Jersey who have yet to regain it after the lights went out more than two weeks ago.

But lessons learned since darkness descended on central New Jersey in the wake of Sandy’s wrecking winds include at least one tiny triumph: Princeton University’s leafy campus stayed lit by tapping its own smaller version of the power grid – a “microgrid.”