Roaring 40s was an electricity generator formed in 2005 as a joint venture between Hydro Tasmania, Australia and Hong Kong-based China Light & Power (CLP). Roaring 40s had 13 sites in operation or in planning in Australia, India, Hong Kong and mainland China. Cathedral Rocks, Woolnorth, Waterloo Wind Farm and Musselroe are four notable power plants that the company owned.

Roaring 40s split in June 2011 with the projects being divided between the two original partners, CLP and Hydro Tasmania.