104 C O R P O R A T E T E C H N O L O G Y | P o w e r E n g i n e e r i n g
Pioneering inventions range from the dynamo, with which Siemens founded the electrical engineering field in 1866 (top) to the high-efficiency com- bined cycle power plant, here linked to a sea water desalin- ization plant in the United Arab Emirates (middle). Gas turbine blades endure extreme stresses (bottom), and superconducting motors could revolutionize marine propulsion (right).
POWERED BY SIEMENS
Siemens has shaped the history of power engineering, and Werner von Siemens started it all with his dynamo machine. His successors are developing environmentally friendly power plants, superconducting engines and fuel cells.
J ust look for the source of your electricity, and sooner or later you’ll come across the name Siemens — often as close as your own fuse box, then at the trans- former building, substation and power plant. The transformers, control units and generators sup- plying your power will very likely bear the “Siemens” label. Power generation — and even the term “electrical engineering” — are closely linked to the company’s founder. In 1866, Werner von Siemens discovered the dynamo- electric principle, and he patented the “dynamo-electric machine” in 1867. This was the first machine to create the magnetic field needed for power generation by
itself. It did so by passing electri- city through an electromagnet. If this type of dynamo is powered mechanically, it creates a field that serves very well for the generation of electricity.
Siemens immediately recog- nized his invention’s scope. By combining his dynamo with a steam engine, he created large quantities of direct current, which was ideal for powering arc lamps. Conversely, if the dynamo was fed electricity, it became a powerful motor.
“This has great potential for de- velopment,” enthused Siemens in a letter to his brother Wilhelm, predicting that “small electromag- netic machines that get their
power from large ones will be- come possible and useful.” His vi- sion is now a reality.
The Siemens company decided to distinguish itself from its com- petition above all through the quality of its engineering work. In 1873, Siemens hired its first physi- cist, Oskar Frölich, whose task was to explore the phenomenon of magnetism. Beginning at the turn of the century, the new metallic- filament incandescent lamps (see p. 92) stimulated more demand for electricity. To supply the “cen- tral stations” (the era’s electric util- ity companies), Siemens built gen- erators, transformers and, from 1927 on, steam turbines as well, achieving increasingly higher lev-
els of efficiency in the process. The key to this was, and still is, de- veloping materials that are resist- ant to high temperatures.
This applies especially to gas turbines. These are driven directly by burning gases — using the same principle as the “fire turbine” presented by a Prussian inventor as early as 1873. Here, fuel is sprayed into compressed air and ignited. The gases drive rapidly ro- tating turbine blades, which pass their energy on to a generator. The conditions inside a “fire tur- bine” aren’t exactly cozy. Tempera- tures exceed 1,400 degrees Cel- sius, with pressures of 17 bar. That’s why components subject to particularly high strain, such as
front turbine blades, are drawn from a melt as single crystals. They are also protected by a ce- ramic coating.
After World War II, Siemens en- gineers developed gas turbines to the level of large scale production. In 1961, the Munich-Obersendling power plant received the first of what would total about 500 Siemens gas turbines. They first proved their value as “stand-ins.” A steam power plant needs hours to reach operating temperature, but gas turbines feed energy into the grid after only a few minutes. To- day, Siemens focuses on building combinations of gas and steam turbines in “combined cycle” plants. In such systems, a roughly 600-degree gas turbine “exhaust” is fed into a boiler, which gener-
ates steam to drive a steam tur- bine downstream — the two tur- bines generate electricity in a ratio of about two thirds to one third.
“We are now manufacturing power plants rated at 58 percent efficiency, and we have designs for 60 percent on the drawing board. This means the combined cycle technology has unbeatable fuel utilization efficiency,” says Bernhard Becker, who oversaw gas turbine development until 1997. With other uses for the heat — as district heating or for the chemical industry, for instance — fuel uti- lization rates as high as 90 percent are achieved. As development continues, Siemens Corporate Technology (CT) researchers are
C O R P O R AT E
always involved, providing new materials and techniques for the ceramic coatings, for example, and conducting 3D simulations of turbine blades and gas flows.
Tomorrow’s combined cycle power plants won’t be limited to burning natural gas. A small up- stream chemical plant could con- vert coal, asphalt or refinery residues into gases that also burn well — without soot, sulfur or heavy metals, and even without carbon dioxide emissions if special separation and storage technol- o g y i s u s e d . “ D r a m a t i c C O 2 r e d u c tions are possible with these plants,” says Becker (Pictures of the Future, Spring 2004, p. 44). -
In Erlangen, CT research teams working on superconductivity and fuel cells have needed even more staying power than their turbine- building counterparts. Both of these projects have been under- way since the mid-1960s. “Fuel cells are still too costly to be used economically in cars, but for use in submarines and in outer space, it’s a different matter,” explains Albert Hammerschmidt of Industrial So- lutions and Services. Siemens has already equipped three German submarines with fuel cells provid- ing more than 150 kilowatts of power. In this case, electricity is generated with pressurized hydro- gen and cryogenic oxygen. “In this area, Siemens is the only manu- facturer worldwide,” says Ham- merschmidt.
With the new, flexible high-
(HTS), CT engineers have also moved a step closer to the dream of the superconducting motor. The temperatures at which such a motor can operate without electri- cal losses are now much higher than when research began in the 1960s. And the cooling system has become correspondingly sim- pler. “The wires are still too expen- sive for commercial use, but soon that will change,” says Heinz-
Werner Neumüller, head of the Power Components & Supercon- ductivity Competence Center.
The new motors could eventu- ally serve as economical, compact power sources installed in rotat- able pods beneath a ship’s hull, improving maneuverability. And they also could usher in a new era inside ship hulls. In August 2005, Siemens researchers started up the world’s first HTS generator, with an output of four mega-volt- amperes. It can power a 50-meter yacht and supply its electricity — at only half the weight and vol- ume of conventional generators. The seas also hold new prospects for Siemens’ fuel cells. “A freight company is testing it as a power supply for docked ships,” says Hammerschmidt. ■ Björn Schaffer
AWARD FOR KLAUS RIEDLE
Klaus Riedle of the Power Gen- eration Group was awarded the “Global Energy International Prize” with its 500,000 euro endowment
a sort of Nobel Prize for power
engineering — in June 2005 in St. Petersburg. Riedle was honored primarily for significant improve- ments in gas turbines. Riedle’s lat- est achievement is the Mainz-Wies- baden power plant, which was completed in 2002. The turbine used in this case generates elec- tricity at an unprecedented level of efficiency while consuming about ten percent less fuel. At operating temperatures of 1,500 degrees Cel- sius, the rotating, red-hot blades must withstand forces equivalent to the pulling power of a 40-ton truck. Ensuring that the system can survive these stresses for decades required extensive modeling of the blade geometry on high-perform- ance computers.
BLOW IT OUT WITH GAS
If electrical contacts are sepa- rated while under high voltage, an electric arc is produced that won’t die out by itself even in a vacuum. In 1930, Siemens caused a sensa- tion with circuit breakers based on the expansion principle invented by Hans Gerdien, who took over the Siemens research lab in 1924. The idea: The electric arc is blown out by a “draft” of gas molecules. The needed kinetic energy is provided by the contacts themselves when they are suddenly separated by strong springs. In 1968, there was another innovation. Siemens sup- plied the first switches to use sulfur hexafluoride (SF6) gas as a quench- ing agent. The advantage: SF6 does- n’t burn and enters into practically no chemical reactions at all. The switches are designed to accommo- date up to 420 kilovolts in normal operation, and up to 800 kV in special cases.
Erlangen Research Center marks 40th year. The devel- opment of solutions for power generation was one of the driv- ing forces behind the establish- ment of the Erlangen Research Center under Heinz Goeschel ex- actly 40 years ago — yet another anniversary in the 100-year his- tory of Corporate Technology. The idea behind the founding of the center was to bring together the regionally and organization- ally scattered R&D activities of Siemens-Schuckertwerke AG. These included the research lab- oratories (Heinrich Welker) for organic chemistry, electrochem- istry, plasma physics and solid state research; reactor develop- ment (Wolfgang Finkelnburg) and the development labs (Wal- ter Hartel), which established the foundations for automation technology.
Pictures of the Future | Fall 2005