Waste-to-energy or energy-from-waste is the process of generating energy in the form of electricity or heat from the primary treatment of waste. Cubes of pressed metal beer and soda cans. Shutterstock Image - Waste-to-energy or energy-from-waste is the process of generating energy in the form of electricity or heat from the primary treatment of waste. Cubes of pressed metal beer and soda cans. - ID: 1011811597