"Our research, advocacy and consulting efforts continue to shift public and private dollars from dirty energy to cleaner energy," said Whittingham.

Raynolds, who began work with the Institute in 1995 and led the organization for seven years, focused his work on improving oil sands development, advancing climate change policies, advocating for renewable energy and energy efficiency, and improving transportation systems in Canada.

"I'm very proud of the growing influence that the Pembina Institute has had on the Canadian energy debate in recent years," said Raynolds.

Gerald Butts, president and CEO of World Wildlife Canada, is also listed in the Clean50 for 2012. Mr. Butts was previously involved in Ontario government environmental initiatives, including for energy and climate change, while working for the Ontario cabinet.

The Clean50, developed by Delta Management, includes 16 categories of sectors, recognizing at least two people in each, based primarily on their impact on sustainable development within the last two years.