Renewable energy group declares cost "turning point"

• It also finds that onshore wind has slightly higher costs but still undercuts about 850 gigawatts of coal by 2021.
• That finding is part of a wider look at falling costs for a suite of renewables technologies and how they stack up to fossil generation.

By the numbers: Retiring the least competitive 500 gigawatts of coal plants and replacing them with solar and onshore wind would save $12 billion to $23 billion annually in power system costs, they conclude.

• That would cut CO2 emissions by 1.8 gigatonnes, which is 5% of last year's global total, per IRENA, the roughly decade-old intergovernmental group that advises nations on renewables policy.

What they're saying: “We have reached an important turning point in the energy transition. The case for new and much of the existing coal power generation is both environmentally and economically unjustifiable," Francesco La Camera, IRENA's director-general, said in a statement.