Japan's biggest power generator Jera is set to start a new 1.07 gigawatt coal-fired power plant in Taketoyo in Aichi Prefecture early next month, which could help to alleviate electricity crunches in the summer and winter.

It is a rare example of a new coal power plant being built in a developed country, as many industrialized nations have been shutting down coal plants for years to reduce carbon dioxide emissions.

Even in Japan, the world's fifth-biggest carbon dioxide emitter, the plan to construct the No. 5 unit at Taketoyo thermal power station to replace three old oil-fired units was unpopular when the utility sought government approval.

The environment minister called for the plan to be reconsidered, or even scrapped, amid growing concerns Japan may miss emissions reductions targets, though the industry minister eventually approved it.

Any additional capacity is welcomed now as Japan is suffering tight power supply and a historic energy security risk as tensions with Russia intensify, heightening the threat of gas supply disruptions.

"We are making final trials to be able to start the unit on Aug. 5," Masato Ishimura, general manager at the Taketoyo power station, told reporters.

"We want to ensure a stable operation to steadily contribute to the tight power market in the summer and winter," he said during a media tour of the facilities.

The unit has achieved a generation efficiency of 46%, among the highest for coal power in the world, and it co-fires biomass to slash emissions, Ishimura said.

For trial runs, Jera uses thermal coals from Australia and Indonesia and pellets from the United States, but it plans to use many other types of coal and import pellets from Southeast Asia.

To meet Jera's goal of achieving carbon neutrality by 2050, the utility plans to consider various options to further cut emissions from the unit in the future, including co-firing ammonia and adding carbon capture storage, he added.

Japan is stepping up efforts to extend the lifespan of its coal power plants in an ambitious project to add low-carbon ammonia to its fuel mix, targeting both stable energy supply and lower emissions in one stroke.