Ecofriendly electricity
To provide the world’s growing population with reliable supplies of electricity while mitigating climate change – this is the challenge now facing energy utilities worldwide. And Siemens – with technologies ranging from the most advanced gas turbines to offshore wind farm systems and low-loss high-voltage direct-current (HVDC) transmission equipment – is delivering solutions.
It doesn’t seem that a two percent increase in efficiency could have much of an impact on climate change. But, when achieved by high-performance turbines and power plants, an improvement of even this magnitude translates into a huge reduction in CO2 emissions – as our SGT5-8000H gas turbine, the latest innovation from Siemens’ Power Generation Group, clearly demonstrates. The 440-ton power pack will be tested as a stand-alone unit in Block 4 of the Irsching Power Plant in southern Germany and then expanded to become a combined cycle power plant, with an output of 530 MWs and an efficiency rating of 60 percent – two percentage points above the current world record. And these two points will make a big difference: They’ll cut CO2 emissions at the plant by 40,000 tons a year – the amount released by 9,500 mid-range cars driven 20,000 kilometer each.
To build a highly compact turbine that can generate huge amounts of power, you need decades of experience in heavy engineering, coupled with the latest manufacturing technology. More than 7,000 individual components – some tiny, others weighing tons – have to be assembled with painstaking precision.
Efficiency ultimately depends on the turbine blades, which must be able to withstand extremely high temperatures and extremely high levels of wear and tear. For the Irsching gas turbine – the largest and most powerful device of its kind, with a power generation capacity of 340 MWs – Siemens engineers developed highly resilient nano coatings that can withstand temperatures of nearly 1,500°C. The experts also developed a hydraulic system that reduces the gap between the rotor blades and the housing by a few millimeters after turbine startup. This design innovation decreases the amount of combustion gases that flow past the blades unused. We’ve already delivered more than 1,100 large gas turbines to customers around the world. In addition, over the past 20 years, we’ve built some 520 fossil fuel combined cycle power plants – facilities that are setting industry standards for energy efficiency and environmental compatibility.
Emissions from our coal-fired plants, which have extremely high efficiency levels of 47 percent, are also significantly below those of their conventional counterparts. In the area of CO2-free coal-fired power generation, our Power Generation Group offers two technologies: post-combustion CO2 capture for existing power plants and pre-combustion CO2 capture for new ones. With our innovative entrained-flow gasifiers – each boasting a thermal capacity of 500 MWs – we’ve developed a key component for clean coal-fired power generation in so-called integrated gasification combined cycle (IGCC) plants.
Offshore wind power systems
In the booming wind power sector – a prime focus of CO2-free power generation – we’re the leading supplier of offshore wind farm systems. Our products include giant wind turbine rotor blades manufactured from fiberglass-reinforced epoxy in a single-cast process based on our patented IntegralBlade technology. To meet the ever increasing demand for wind power systems, we’re expanding our production capacities.
Our largest wind turbine, the SWT-3.6-107, which has a rotor diameter of 107 meters and a capacity of 3.6 MWs, is being used in several major European wind power projects. We’ve installed 54 of these turbines at the Lynn and Inner Dowsing wind farm off the east coast of England. When completed at the end of 2008, this facility – the largest offshore wind farms in the world – will supply clean energy to 130,000 households. We’ll be responsible for servicing and maintaining the farm’s turbines during the facility’s first five years of operation. Since 2003, we’ve installed wind turbines with a capacity of more than 3,300 MWs – a boon to the environment, since generating the same amount of electricity in a fossil fuel power plant would produce about eight million tons of CO2.
High-voltage direct-current transmission
Wind farms and hydropower plants are almost always located at a considerable distance from the population centers and industrial regions where most electricity is consumed. As a result, power often has to be transmitted over vast distances and, when generated at offshore wind farms, via undersea cables. Systems using alternating current are not economically feasible for long-distance applications since too much energy is lost during transmission. High-voltage direct-current (HVDC) systems – although technologically more complex – are the optimal solution, because they minimize energy loss. As a leader in HVDC transmission technology, we’ve already installed several of these low-loss systems worldwide.
In India and China, for example, we’ve constructed HVDC transmission lines stretching more than 1,000 kilometers from power plants to consumers. And in the U.S., we’re linking the residents of New York’s Long Island with a power grid on the New Jersey mainland via a 105-kilometer HVDC undersea cable. Siemens converter stations transform alternating current into direct current at the New Jersey end and then reconvert it into alternating current when it reaches Long Island. The system’s advantages: fewer CO2 emissions – since the power from the mainland comes in part from CO2-free generation – and fewer power plants on the densely populated island.
But Asia and the U.S. are not the only places where our HVDC transmission technology has scored major successes. It’s also been extremely well received in Europe, where we’ve landed three orders for HVDC systems in the last six months alone. Most recently, in September 2007, we signed a contract with Spanish network operator Red Eléctrica de España to link the island of Majorca with the mainland power grid via a 400-MW 250-kV HVDC undersea cable stretching 250 kilometers. The largest of the Balearic Islands, Majorca has a permanent population of some 790,000 people. In addition, up to seven million vacationers flock to the island every year. Thanks to the new HVDC link, power demands during the peak holiday season can now be met by electricity imports from the European continent. We’ve also received orders to supply converters for the 600-MW 400-kV Storebaelt undersea link, which will run between the Danish islands of Funen and Zealand, and for the 1,000-MW 450-kV BritNed undersea link, which will connect the Netherlands and Great Britain.
HVDC Plus is what we call our latest innovation in hight-voltage direct-current technology. The advantages of the new system, which employs voltage-sourced converters, include the compact dimensions of the converter stations used and the system’s ability to link large power grids to weak power systems. Our HDVC Plus solution will open up new opportunities for low-loss power transmission – for instance, from offshore wind farms to the mainland, from the mainland to offshore oil platforms, and from remote power plants to large urban areas. The solution is being implemented for the first time in San Francisco, where it will significantly increase the security and reliability of the city’s power supply network.
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