Bloomberg New Energy Finance (BNEF) finds a dramatic transition from roughly two-thirds fossil fuels to 56% of power produced by zero-emissions energy sources by 2040.

A reduction in costs will drive the expansion of solar and wind technology. Utility scale solar will likely be the lowest cost producer by 2030. Solar power will make up 35% or 3,429GW of capacity additions - making it the top technology in capacity additions for the next 25 years.

Developed countries in the OECD will shift from centralized power systems to decentralized systems. This shift will be dominated by small-scale PV. Meanwhile, developing non-OECD countries will build three times the power capacity as developed nation as a result of economic growth and expanding electricity markets. Coal and utility scale PV will be tied for these new additions.

The Asia Pacific region will build more than half of new generating capacity over the next 25 years. Europe will see coal capacity halve and nearly 50% of generation come from variable sources like wind and solar. In the United States, gas will dominate new capacity until 2020, after which small scale solar will take the lead. Latin America will invest heavily in wind and solar to shift away from hydro power. In the Middle East and Africa, fossil fuels will be nearly 40% of new capacity due to their large reserves. Solar PV is forecasted to increase by 160GW in the Middle East and Africa, as these countries have excellent solar potential. 

(Please note that BNEF's Executive Summary is provided here and the full report can be bought from them here.)