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enewable energy is undoubtedly the most sustainable answer to the rising energy demands. And hydropower plays a key role in sustainable and environment-friendly power generation from regenerative energies. Hydropower is the leading renewable source of electricity generation globally, supplying 72 per cent of all renewable energy in the worldwide electricity mix. In summary, one can say that hydropower is renewable, reliable, affordable and beneficial for both economic and social development.In 2015 renewables accounted for more than half of all the new electricity generation capacity globally for the first time. Reaching 1,064 gigawatts of installed capacity in 2016, hydropower generated 16.4 per cent of the world’s electricity, taking all sources into account. In comparison, a typical power station generates one gigawatt of power (one billion watts). The Hoover Dam hydropower plant in the US produces two gigawatts and the Three Gorges Dam in China holds the record for the most powerful hydropower plant on earth generating more than 18 gigawatts. But this is just the current picture. By 2040 power generation from renewable energies will increase to a third of today’s total energy production. Hydropower will play a major role in this , as worldwide hydropower generation will increase as well. In addition, hydropower offers the possibility of storing electricity. In this way, it can balance the power grid with high flexibility.What is the secret of hydropower? It is the very efficient and CO2 free transformation of the mechanically stored (by nature) energy in water into electrical energy – first by the turbine into the mechanical torque of the machine’s shaft, and then through the conversion of shaft torque into electrical energy by the generator.There are three types of hydropower stations which can be used to exploit the energy stored in water. First, there is the ‘run-of-river’ power station, where the electricity is generated from flowing water in a river. Second, there is the ‘reservoir’ energy source, where power is generated through the release of stored water. This traditional power station uses a dam to store river water in a naturally fed reservoir. A third model is the ‘pumped storage’ power plant, where stored water is recycled by pumping it back up to a higher reservoir to be released again. These types of hydropower plants provide energy for a base-load operation as well as sufficient flexibility for quickly balancing power and ensuring system adequacy during periods of low production from renewable sources. THE WORLD’S INCREASING DEMAND FOR ENERGYIt is no secret: the world’s demand for power is increasing. And it is not only the rise in industrial production which is rising the world’s energy demand. Take the current use of the internet as an example. Within the next two years – according to the estimates of an international software manufacturer – over one half of the world’s population will have access to the internet. Today it is only about one third. This ongoing development is accompanied by increased usage intensity – the buzzword being ‘data streaming’. In the very near future, as early as 2019, approximately 80 per cent of the requested data volume will be the streamed data. Transmitting bytes across the internet, accounts for the bulk of energy usage and emissions when streaming videos. The increase in streaming will foreseeably increase the demand for energy and this means that we are facing a big challenge. Today, the annual average total power consumption of the human world already amounts to 1 terawatt (one trillion watts).USING UNEXPLOITED POTENTIALS AT EVERY SCALEThe hydropower facilities installed today vary in size from less than 100 kilowatts to more than 18 gigawatts. They are equipped with individual turbines with up to 1,000 megawatt capacity each. Voith has been a leading supplier of this technology since the very beginnings in 1870 and has been advancing the technology ever since. More than ever before, the challenge will be to build an infrastructure that delivers power to homes and businesses reliably, and also utilize the unexploited power potential across the world.In most of the highly-developed countries the potential of technically usable hydropower is far from exhausted. Countries such as China and Brazil are the role models for improved power exploitation. China operates the world’s largest hydropower plant (Three Gorges Dam, 18,200 megawatts) and RSUSTAINABLE ENERGY 089