In its New Energy Outlook 2015 report, BNEF said wind is already the cheapest new form of energy capacity in Europe, Australia and Brazil. And by 2026, it will be the "least-cost option almost universally".
However, the report suggests large-scale solar PV will become the cheapest globally by 2030.
BNEF believes wind project costs will reduce by 32% by 2040 because of "steep experience curves and improved financing". The price for solar is expected to fall 40%.
The report adds renewable energy will double to 46% of the world's electricity output, "with variable technologies such as wind and solar accounting for 30% of generation". In 2014, this level stood at 5%.
Significant growth in renewables will require a large amount of investment. The report predicts: "Renewables will command just under 60% of the 9,786GW of new generating capacity installed over the next 25 years, and two-thirds of the $12.2 trillion of investment."