Pictures of the Future      Fall 2005

Powered by Siemens

Just 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 transformer building, substation and power plant. The transformers, control units and generators supplying 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 dynamoelectric 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 electricity 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 recognized 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 development," enthused Siemens in a letter to his brother Wilhelm, predicting that "small electromagnetic machines that get their power from large ones will become possible and useful." His vision is now a reality.

The Siemens company decided to distinguish itself from its competition above all through the quality of its engineering work. In 1873, Siemens hired its first physicist, Oskar Frölich, whose task was to explore the phenomenon of magnetism. Beginning at the turn of the century, the new metallicfilament incandescent lamps (see "Let there be Light") stimulated more demand for electricity. To supply the “central stations” (the era’s electric utility companies), Siemens built generators, transformers and, from 1927 on, steam turbines as well, achieving increasingly higher levels of efficiency in the process. The key to this was, and still is, developing materials that are resistant 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 rotating turbine blades, which pass their energy on to a generator. The conditions inside a "fire turbine" aren’t exactly cozy. Temperatures exceed 1,400 ° C, 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 ceramic coating.

After World War II, Siemens engineers 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. Today, 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 generalways ates steam to drive a steam turbine downstream—the two turbines generate electricity in a ratio of about two thirds to one third.

Tomorrow’s combined cycle power plants won’t be limited to burning natural gas. A small upstream chemical plant could convert 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 technology is used. "Dramatic CO₂ reductions are possible with these plants," says Becker (see Pictures of the Future, Spring 2004, "Clean Future").

In Erlangen, CT research teams working on superconductivity and fuel cells have needed even more staying power than their turbinebuilding counterparts. Both of these projects have been underway 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 Solutions and Services. Siemens has already equipped three German submarines with fuel cells providing more than 150 kW of power. In this case, electricity is generated with pressurized hydrogen and cryogenic oxygen. "In this area, Siemens is the only manufacturer worldwide," says Hammerschmidt.

With the new, flexible hightemperature superconductors (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 electrical losses are now much higher than when research began in the 1960s. And the cooling system has become correspondingly simpler. "The wires are still too expensive for commercial use, but soon that will change," says Heinz-Werner Neumüller, head of the Power Components & Superconductivity Competence Center. The new motors could eventually serve as economical, compact power sources installed in rotatable 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 4 MVA. It can power a 50-meter yacht and supply its electricity—at only half the weight and volume 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