Steam Turbine - Water as Energy Carrier

When you operate the light switch at home, the light goes on. That is a matter of course for most people. The current 'flows' through the light bulb, and the energy is released as light and heat.

But Where Does This Energy Come from?

In Austria, a lot of electric energy is generated in hydroelectric power plants, but the major part is generated in thermal power stations. And in these power plants, steam turbines are generally used.

Picture: Modern thermal power plant in Hanover/Germany. Hard coal is used as fuel.

Already the Old Greek Knew...

The working of the steam turbine is based on a principle that has already been known for a long time. Already Heron from Alexandria developed a kind of steam engine in classical antiquity. Its predecessors were the steam engines that were responsible for the industrial revolution in Europe. They had a major drawback, though - very low efficiency. That means the ratio of energy put in in the form of coal or something similar to the generated energy was very low. Only the invention of the steam turbine brought about a thermal engine with a satisfying efficiency of up to 45%.

Principle

Like in a steam engine, high pressure steam is generated in a boiler. The steam is channelled to nozzles, where it escapes with high speed. Next, the steam hits the slightly tilted paddles of a runner with high kinetic energy. When that happens, the paddles are moved aside similar to the paddles of a wind turbine. The runner is set into rotation. The steam performs acceleration work at the expense of its kinetic energy. Since the steam has more kinetic energy at the beginning of the turbine than at its end, the shape of the paddles has to be adjusted. At the end, they are longer than at the beginning. Thus, an undisturbed movement of the steam through the turbine is achieved.

Picture: Paddles of a Steam Turbine

Ultimately, the inner energy of the fuel, which is released at the boiler during the incineration, is transformed into mechanical energy in a steam turbine. The steam functions as energy carrier.