When Japan narrowly avoided blackouts this summer, part of the success was down to aging coal-fired power stations like Takasago Thermal Power Plant.

Even as the nation aims to shift to cleaner energy sources, it remains heavily reliant on sites like Takasago, built in 1968 and considered far past retirement age. The plant, owned by Electric Power Development, or J-Power, has become even more vital amid a global energy crisis and shutdown of nuclear reactors since the Fukushima disaster.

"Usually, it’s good enough if a power plant operates for 20, 30 years,” said Hiroyuki Uchinaga, an official for J-Power’s maintenance unit and head of the Takasago plant, located in an industrial zone near Kobe. "We’re entering uncharted territory after operating for over 50 years.”