Ключевые слова: alternative, biofuel, biomass, brown, clean, cleanenergy, closeup, concepts, conservation, construction, cylinder, development, energy, environment, environmental, fuel, generation, hardwood, harmony, horizontal, illustration, industry, life, log, lumber, material, nature, new, nobody, organic, paper, power, recycle, recycling, reduce, resources, sign, stack, stacked, surface, sustainable, symbol, technology, textured, timber, tree, wood, yang, ying, yingyang,