tailieunhanh - Energy A Beginner’s Guide Part 9

Năng lượng tối Có vô hạn dạng: Sóng; Tia; Trường .là năng sẽ mất đi nếu không có điều kiện tụ kết thành một dạng Năng lượng Hạt = vật chất Hạt, nào đó. Năng lượng tối có dạng sơ khai là "Vật chất Mịn=không gian mêtric có sự thay đổi sắp xếp. | 150 energy a beginner s guide Basic construction materials require only extraction wood sand and stone and heat processing bricks cement and glass . Despite the near-total mechanization of modern lumbering a tonne of wood costs only about toe as does the most efficient brick drywall gypsum between paper boards commonly used in North America and cement production. Making concrete a mixture of cement sandy or gravel aggregate and water adds less than 25 kgoe but reinforcing it with steel is nearly three times as energy expensive. The most energy-intensive materials commonly used in house construction are insulation and plate glass both in excess of toe t. Integrating these inputs for entire buildings results in totals of around 12 toe for an average three-bedroom North American bungalow and more than 20 000 toe for a 100 storey skyscraper of 1000 m2 per floor. In commercial buildings and residential highrises steel is most commonly the material with the highest aggregate energy cost. ENERGY COST OF METALS Steel remains the structural foundation of modern civilization it is all around us exposed in vehicles train and ship bodies appliances bridges factories oil drilling rigs and transmission towers or hidden in reinforced concrete and skyscraper skeletons touched many times a day kitchen and eating utensils surgical instruments and industrial tools or buried underground pipes pipelines and piled foundations . Globally about thirty per cent is now made from recycled scrap but most still comes from large blast furnaces. Technical advances lowered the typical energy cost of pig iron so-called because it is cast into chunky ingots called pigs to less than toe t by the early 1970s. The most highly efficient operations now produce pig iron for less than toe t. Pig iron is an alloy that contains from per cent carbon while steel has almost no carbon or no more than two per cent . This seemingly small quantitative difference results in enormous .