字幕表 動画を再生する 英語字幕をプリント Aluminium is lightweight, durable, and 100 per cent recyclable. In fact, 75 per cent of all the aluminium ever produced is still in use. It's a key input for companies such as tech giant Apple and electric car makers, and an essential material in industries such as construction and power transmission. For that reason, demand is expected to grow by more than 50 per cent by 2050. But aluminium production requires a lot of energy. Aluminium comes from an ore called Bauxite, and smelting it is an electricity-hungry process. Today the aluminium sector contributes about one per cent of global greenhouse gas emissions. But as concerns mount over climate change, the pressure to produce greener aluminium, with renewable energy sources, may gradually be rising. Some major producers such as Russian giant Rusal, and Norway's Norsk Hydro can already produce low-carbon aluminium. Over 90 per cent of Rusal's aluminium is now made using hydroelectric power, while two-thirds of Norsk Hydro's is produced using renewable energy sources. But China produces more than 60 per cent of the world's aluminium, mostly from coal-fired power. The production of one tonne of aluminium in Europe, which largely uses renewable energy, creates about four tonnes of carbon dioxide, compared with 15 tonnes in China. Now though, for the first time in its 143-year history, the London Metal Exchange, the world's main trading centre for industrial metals, is planning to launch a platform for low-carbon aluminium. The idea is to encourage more sustainable production. But critics say a single carbon calculation is overly simplistic, focused too much on primary smelting. They say it runs the risk of overlooking the impact of other parts in a complex supply chain, such as the mining of bauxite. Also, low-carbon producers with existing sales contracts may not want the market setting prices for them. Consensus on the plan has yet to be reached, and for now, disclosure of CO2 emissions to the exchange remains voluntary, but the appetite for greener aluminium could be here to stay.