From Pittsburgh to Frankfurt, cities around the world are pledging to stop burning fossil fuels for electricity by 2050 or sooner.

But the Chinese province of Qinghai has already reached that goal, according to news outlet Xinhua. For seven days — from June 17 to 23 — the region ran on 100% renewable energy, including solar, wind, and hydropower.

The week was part of a trial conducted by the State Grid Corporation of China, which aims to test the viability of relying on renewables long-term. During that time, the Qinghai province generated 1.1 billion kilowatt hours of energy for over 5.6 million residents. That's equal to burning 535,000 tons of coal.

Hydropower contributed to approximately 72% of the electricity generated during the seven days, Xinhua News said. As of May 2017, Qinghai’s power grid had a total installed capacity of 23.4 million kilowatts, with around 82% of that capacity made up of solar, wind, and hydro sources. By 2020, the province plans to expand its clean energy capacity to 35 million kilowatts, which could supply 110 billion kWh of renewable energy annually.

Nationwide, China hopes to produce 20% of its electricity from clean sources by 2030. Despite the recent rapid growth of clean energy, wind power accounted for just 4% and solar for about 1% of China’s electricity in 2016, according to The Guardian.

Qinghai is not the first place to run on 100% renewable power. Tokelau, a set of three tiny islands between Hawaii and New Zealand, replaced its diesel energy system with one that uses solar in 2012. And Costa Rica ran on 100% clean energy for 285 days in 2015, and on 98% renewables for 250 days in 2016. Austria's largest state also currently gets all of its energy needs from solar, wind, and hydropower.

These efforts signal that a power grid that doesn't rely on fossil fuels is possible for other cities, too.