17 US states are at risk of a blackout due to extreme heat (Picture: Getty Images)Around 20 million Americans across 17 states are living with the threat of a potential blackout. Specifically, authorising the operator serving parts of 17 states to activate idle power sources. Former DOE official Kerry Duggan has said that, unfortunately, extreme heat across the US is becoming a very real energy challenge. It’s not just extreme heat Americans have had to deal with in recent weeks, either. It also marked the second tropical storm this season — following on from Tropical Storm Arthur in June that caused flash flooding and tornadoes in portions of the south.