Japan on Friday unveiled plans to boost renewable energy, phase out gasoline-powered cars and reduce battery costs as part of a bid to reach an ambitious 2050 carbon-neutral goal.

Prime Minister Yoshihide Suga announced the new 2050 goal in November, significantly moving up Japan's timeline for carbon-neutrality.

On Friday, his government laid out for the first time what meeting that target will involve, including setting a provisional goal of generating more than half of the country's electricity from renewable sources by 2050.

"The government's actions on the environment reflect our belief that a significant change of mindset is required and that these are not constraints for growth, rather they are drivers of growth," top government spokesman Katsunobu Kato told a regular briefing.

Japan, which is a signatory to the Paris climate deal, has been seen as reluctant to reduce its reliance on fossil fuel, despite its self-professed pride as a nation of energy-saving technologies. 

The country was the sixth-biggest contributor to global greenhouse emissions in 2017, according to the International Energy Agency.

The world's third largest economy still relies heavily on coal and liquefied natural gas, with most of its nuclear reactors offline since the 2011 Fukushima disaster.

Japan expects demand for electricity to surge 30-50 percent by 2050, but the nation's conservative ruling party has so far stayed lukewarm about renewable energy, though Suga has shifted the tone in recent weeks.

Under the plans to boost renewables, officials are placing a new focus on offshore wind generation, with the goal of producing up to 45 gigawatts within the coming decades.

Japan also wants to use nuclear and thermal power plants with carbon capture technology to cover 30-40 percent of the nation's electricity demand.

Ammonia and hydrogen technologies are expected to fulfil about 10 percent of the nation's power needs.

By the mid-2030s, the government also wants to end the sale of new passenger vehicles that are solely powered by gasoline.

Japan plans to replace them with hybrids, electric cars and cars fitted with fuel-cell engines, while bringing down the cost of batteries for those vehicles.

But while officials say the new plan is ambitious, some critics believe it falls short.

Mika Ohbayashi, director of the Renewable Energy Institute, said the figures were "a poor starting point for discussions and (showed) a lack of ambition."

Japan should aim for renewable energy to cover 50-60 percent of national electricity needs by 2030, rather than wait until 2050, the think tank said.

The institution also voiced its scepticism about whether carbon capture technology will become widely available in the coming decades -- an assumption made by Japan as well as other nations in their carbon-neutral plans.