REX - Regional Express

energyspecial Waste opportunities Ed Sugay, Head of Energy Efficiency at Siemens, identifies ways to transform waste energy into cost-saving and environmentally sustainable processes. About half of the primary energy consumed in industrial processes is currently wasted. Even steel produced by recycling scrap metal in electric-arc furnaces, for instance, requires approximately 370 kilowatt hours per metric tonne. In this type of furnace an electric arc is struck between several electrodes. The resulting heat causes the steel to melt before emitting a mixture of gases at up to 1,700 degrees Celsius – a huge waste that might otherwise be used in the process of, or to generate, electric power. Siemens is looking at ways to intelligently utilise as much waste energy as possible. Predictions suggest that about 50 per cent of costs from operating a mine will come from energy, making it even more of an incentive for industries to reduce energy consumption, as well as manage waste more cleverly. This is the philosophy behind the company's energy efficiency unit: doing more with less energy. When considering energy efficiency, one often thinks of energy-saving technologies for lighting, heating and air-conditioning. However, energy efficiency is so much more than that; it's about reducing consumption while at the same time making the most of wasted energy by using it in other parts of the process or by condensing it to generate electricity. According to Siemens R&D experts, up to 20 per cent of the energy needed for melting scrap metal could be recovered from waste heat. This would reduce CO2 emissions per metric tonne of steel by about 40 kilograms. Current systems emit about 270 kilograms of CO2 , 220 kilograms of which results from power generation. This means CO2 emissions from a typical 120-metric-tonne furnace could be reduced by more than 30,000 metric tonnes annually. While it makes sense to recover wasted heat, most industrial waste heat is still not captured for reuse, and about half of the primary energy consumed in industrial processes and energy generation currently goes to waste. Part of the problem is the fact that there are still hardly any economically practical and technically mature processes available for waste heat below 300 degrees Celsius. In a study on thermal management, Siemens has identified a process called Organic Rankine Cycle technology (ORC), which is particularly suited for recovering waste heat from furnaces in the glass industry, diesel or gasoline engines, gas flaring at refineries and gas turbines in compressor stations. The non-polluting organic medium used in this process ensures optimal efficiency for low waste heat temperatures and low power. In a trial at Moscow State University, the ORC produced about 800,000 kilowatt hours of extra electricity per year with an efficiency of about 20 per cent and a payback of within three years. In addition to producing electricity, waste heat can be used to clean water. This innovative concept is the driver behind an evaporation Fast Facts and condensation process called EvaCon Siemens is ranked – another Siemens R&D project – which number one on the uses low-grade heat from industrial Dow Jones Sustainability processes that is too low for electricity Index, and in 2012 the generation to instead purify and create company recorded an demineralised water. This not only average of 41 new generates new fresh water for re-use but inventions per day. also reduces the amount of wastewater that might otherwise go to sewage. Paper mills, soft drink bottling plants and other industries where wastewater cannot be readily disposed via a sewage treatment plant could potentially benefit from EvaCon. Top row: Organic Rankine Cycle technology (ORC) was trialled at Moscow State University, resulting in 800,000 kWh of electricity produced in one year from waste heat. Bottom row: EvaCon uses low-grade waste heat from industrial processes to purify and create demineralised water. 89

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