Ключевые слова: alternative energy, backgrounds, beech, bio fuel, biofuel, biomass, biomasse, black, briqettes, brown, bundle, close up, closeup, cylinder, directly above, energy, environment, fossil fuel, fuel and power, group of objects, heap, horizontal, large group of objects, material, nature, oak, organic, pellet, pellet gun, pellets, pine, renewable energy, sunflower, sunflower pellets, wood, wood chip, wood pellet, wood pellets,