Central European powerhouse Poland will anchor its energy strategy in coal and shale gas, with only limited investment in renewables, Prime Minister Donald Tusk said Tuesday.

An EU nation of 38 million people, Poland currently relies on its vast coal reserves to produce about 90 percent of the electricity it consumes.

While experts agree it has nearly 150-years worth of domestic coal deposits, Warsaw has nevertheless been scrambling to find alternatives to meet EU targets on reducing greenhouse gas emissions.

"We want to have renewable energy sources, but hard coal and lignite -- and soon shale gas -- will remain our principal energy sources. That's where the future of the energy sector lies," Tusk told reporters.

He spoke at the opening of a coal industry trade fair in the southern Katowice coal basin.

"...we've decided that renewable energy sources, which are an important complement to Poland's energy sector, will be limited as much as EU rules will allow," he said.

The government believes tapping its own shale gas deposits could assure strategic energy independence from Soviet-era master Moscow.

Warsaw had also planned to invest an estimated 9 to 12 billion euros ($11.3-15.5 billion) in its first two nuclear plants by 2024 to feed the needs of its growing energy market.

But Tusk said in June there would likely be a delay, as natural gas, including shale gas, becomes less costly on global markets and made no mention of nuclear power on Tuesday.

Tusk also voiced optimism that new technologies allowing for cleaner coal-fired plants would be key to Poland's strategy.

He said last year Poland would invest 100 billion zloty (23.5 billion euros, $31 billion) in its energy sector by 2020.

Total investment in exploration and development of the shale gas sector by domestic and foreign companies could reach 12.5 billion euros.

Optimistic estimates suggest Poland could have up to 1.92 trillion cubic metres (67.8 trillion cubic feet) of exploitable shale gas deposits, possibly the third largest reserves in Europe after Norway and the Netherlands.

Last month, Lane Energy Poland -- controlled by US energy giant ConocoPhilips -- began shale gas extraction at a test well in northern Poland.

It was a first for Poland, though the amounts involved are too slight for commercial production.