Energy cells were small items found at Locations in Destroy All Humans! Big Willy Unleashed. Energy cells were small, diamond shaped objects with energy that flowed through them. While Energy cells were usually found all over each map, they were also given by completing missions. Energy cells were used to upgrade Weapons, making it the replacement for the Furotech cells found in Destroy All Humans! 2. The exact reason for why they are found everywhere, isn't explained.