Poland is struggling to make "coal" less of a dirty word as it hosts U.N. talks on slowing global warming that usually focus mostly on phasing out fossil fuels in favour of renewable energies such as solar and wind power.

Coal-dependent Poland has angered environmentalists and put the United Nations in a quandary by planning a coal industry summit next week on the sidelines of Nov. 11-22 U.N. talks among 200 nations seeking ways to slow global warming.

Warsaw says governments must find ways to cut emissions from coal, a cheap and often highly polluting energy source that generates 40% of world electricity, and not pretend that it will simply wither away in favour of greener energies.

"Coal is still the basic source of energy in many countries in the world. So a transition period is needed," deputy environment minister Beata Jaczewska said of the Nov. 18-19 meeting organised by the World Coal Association (WCA) and Poland's economy ministry.

But many environmentalists say coal distracts from a U.N. drive to restructure the world economy around cleaner options, from hydro- to geothermal power. Some also object to efforts to capture and bury the carbon emissions from coal.

"Coal is not the solution," said Martin Kaiser of Greenpeace. He called the coal talks a "slap in the face" to developing nations that are suffering extreme weather and want rich countries to take the lead in phasing out fossil fuels.

Coal-fired power plants are the biggest single source of manmade greenhouse gas emissions blamed by a U.N. panel of climate scientists for pushing up temperatures and causing more heatwaves, droughts and rising sea levels.

Appeal Rejected

"We can burn coal more cleanly. It's not science fiction," Milton Catelin, head of the WCA, told Reuters, adding that the coal meeting was a "constructive contribution" towards a U.N. deal, meant to be agreed in 2015, to slow global warming.

He said that raising the overall efficiency of the world's coal-fired power stations to the standards of a modern plant would cut global carbon dioxide emissions by about 2.4 billion tonnes, roughly the equivalent of India's total emissions.

Poland generates 90% of its electricity from coal. Among European Union members, it has been one of the most reluctant to toughen the existing goal of cutting greenhouse gas emissions by 20% below 1990 levels by 2020.

Christiana Figueres, the U.N.'s climate chief who says the world should aim to eliminate net carbon emissions by the second half of the century, rejected an appeal by environmentalists to cancel plans to attend the coal meeting.

"I will speak to the coal industry to show them that they can and must immediately deploy policies and technologies to lower their industry's carbon footprint more swiftly and urgently," she told Reuters.

She said, however, that she would not endorse a communique at the summit that Catelin of the WCA said he hoped Figueres would sign.

It calls for immediate use of "high-efficiency low-emissions coal combustion technologies" and urges development banks to step up lending for coal projects even though the World Bank and others are cutting back.

As head of a U.N. group, "I would not be involved in any communiques by external groups", she said in an email. In the past, she has had little good to say about coal.

"Kudos to World Bank for restricting financing of coal. Important step towards low-carbon global economy," she wrote on Twitter in July when the World Bank said it would limit lending for coal-fired power plants to "rare circumstances".

Poland is among nations planning investments in coal and has also sought to develop cleaner-burning shale gas, which has helped the United States cut its greenhouse gas emissions.

The nation's plans include construction of a 1.08-gigawatt coal plant by 2017 by the country's third-biggest power producer, Enea, in Kozienice, central Poland. (Writing by Alister Doyle; Editing by Dale Hudson)