A year after losing the number one spot to China, the US leapfrogs the Asian giant to again lead the business services group's quarterly Renewable Energy Country Attractiveness Index (RECAI) thanks to President Barack Obama's Clean Power Plan (CPP).

The CPP, announced in August, is "the most comprehensive, far-reaching and flexible emissions legislation in the US to date, and gives a clear steer on the country's long-term energy strategy", said EY Global Power & Utilities corporate finance leader Ben Warren.

"Targets