LEAP, which Charlie has been developing since 1990, is a powerful, versatile software tool for integrated energy planning and climate change mitigation assessment. In 2014 alone, more than 2,000 people actively used the tool, and the LEAP online community, COMMEND, has grown to over 22,000 members in 191 countries.

Along with developing LEAP and managing COMMEND, Charlie works around the world conducting workshops, undertaking energy studies and providing training and assistance to users of LEAP.

Charlie has also developed a range of other software tools and websites for energy and environmental planning, including GreenTrips (a web-based tool for households to plan their transport emissions), and IDENTIFY (a spreadsheet-based tool for industrial climate mitigation project planning developed for UNIDO).

In addition, Charlie has been a major contributor to the development of other SEI software tools, including WEAP, REAP and PoleStar.

Charlie has a B.S. (first class) in energy studies from the University College of Swansea in Wales, and a Ph.D. in environmental technology from the Imperial College of Science and Technology in London.