John Twidell has considerable experience in renewable energy as an academic professor in both the UK and abroad, teaching undergraduate and postgraduate courses and supervising research students and fellows. He has participated in the extraordinary growth of renewable energy as a researcher, journal editor, board member of wind and solar professional associations, and company director. University positions have been in Scotland, England, Sudan and Fiji. The family home operates with solar heat and electricity, biomass heat, all-electric cars, energy management and a large vegetable garden; the aim is to practice what is preached! Online Resources Julie Alexander has been teaching physics for 35 years at the University of Victoria and Camosun College in Victoria, British Columbia, Canada. She holds a PhD in climate modeling and has recently developed a one semester course in renewable energy that she teaches to second year mechanical engineering students. After an extensive search for a suitable textbook she chose the third edition of Renewable Energy Resources by John Twidell and Tony Weir. She is looking forward to using the updated fourth edition of this book for her courses in the future. Julie also enjoys competitive rowing and playing the violin. https://juliealexander.ca jalex@camosun.ca