Last week, the nation of Portugal achieved something remarkable. For 107 hours -- about four days -- the country ran on nothing but wind, solar and hydro power. AP Photo/Armando Franca
Running a country of about 10 million people without any fossil fuels is certainly an impressive feat. The weather helped: sunny, breezy days optimised energy-collection and mild temperatures didn't strain the grid with excessive heating or cooling needs. Of course, this figure only nods to utilities -- it doesn't include the petrol-powered vehicles on streets. But it does mean that any electric vehicles that were charged during that period were truly zero-emission vehicles.
As recently as 2013, Portugal generated half its electricity from combustible fuels, with 27% coming from nuclear, 13% from hydro, 7.5% from wind and 3% from solar, according to Eurostat figures.
By last year the figure had flipped, with wind providing 22% of electricity and all renewable sources together providing 48%, according to the Portuguese renewable energy association.
Other European countries are pushing towards similar goals. Germany got close to a zero-emission day recently, and the UK recently celebrated a coal-free week as part of its pledge to go entirely off coal by 2025. Denmark -- ever the paragon of environmentalism -- is routinely generating more energy than it needs from wind.
How soon until the US can celebrate a zero-emission day? Their renewable energy share is still relatively low, and while it is slowly growing, they have a lot more work to do in order to wean themselves off fossil fuels. Coal production might be plummeting in the US, but natural gas and nuclear are still very popular options, making up more than half of US power sources. And in Australia, 73 per cent of energy came from coal and 13 per cent from natural gas as of 2015. Still, that doesn't mean it's impossible.