"To separate energy from matter in the manner you suggest is certainly material for a nice and purely intellectual exercise, but we do experience this world physically, and energy comes from several materials. Petrol, for example, is something we use to release energy, but it is also matter. I do not believe we have found a process by which we can extract or use energy from a source that was not material, as such physical, as of yet."

According to Albert Einstein, all matter is in "reality" slowed down energy. That btw is the meaning of his famous equation E = mc^2.

"We have seen the enemy, and he is us!" (POGO)