Since the days of Nikola Tesla free energy has been invented and reinvented. These were the days before electrical engineering principles were solidified into a set of rules that assumed all was known. Then, inventors could think outside of a box that had not yet been formed.
This book may give you:

• Strategic Energy Innovations: Electrical Engineering Principles
• Complete Energy Innovations: Electrical Energy Inventions
• Renewable Energy Innovations: Free Energy Machines