Private equity firms and their investors are turning away from renewable energy investments and focusing their attention on deals to extract and produce fossil fuels, as massive discoveries of shale gas in the United States push down energy prices and put returns from renewable energy investments under pressure.

The move marks a U-turn for the buyout firms that pumped cash into buying and developing big renewable energy infrastructure projects in the aftermath of the credit crisis. In 2010 and 2011, firms including Blackstone Group, Kohlberg Kravis Roberts and Terra Firma invested in a string of renewable energy businesses developing offshore wind farms in Germany and solar power plants in Spain and Italy. At the time, conventional buyout deals in more traditional sectors were few and far between.