What is Energy?

My boyfriend works in a company which manufactures gas turbines. A few months ago the term 'gas turbine' belonged to my list of boring words that I didn't have any desire to learn about. However, lately things have changed.

Two weeks ago I had the incredible opportunity to experience a guided tour in Beznau Nuclear Power Plant. I did not suspect this would be such a memorable event, but it gave me such an enlightenment about the source of energy, that I feel it deserves a short description.

The Power Plant was using the abundant Uranium as a fuel to supply electricity to all cantons in NE Switzerland. The Beznau Power Plant is one of the many plants of the NOK (Nordostschweizerische Kraftwerke AG). Both nuclear and river-based hydroelectric plants cover the base load - this is the electricity that is usually needed in this part of Switzerland. When there are peak periods with more electricity required, it is provided by other kinds of power plants, which take less time to switch on and off. The most important rule is that the electricity produced at each moment should be equal to the electricity consumed.

Beznau Power Plant was cleverly situated on the island Beznau, which is in the river Aare. Three main reasons for that: huge amounts of water were needed for different (mainly cooling) functions inside the plant; the region is with a big electricity demand so the costs for electricity transport are minimized; the site is easily reachable by car and trains.
Furthermore, in order to make the best use of the island, the other end is the home for a hydroelectric plant.

Why Uranium? Because it is everywhere and is easily extracted. The electricity produced from 1 Tonne Uranium = electricity produced from 10 000 Tonnes Oil. In addition, big reserves are easy to store in a small area. Beznau always has enough Uranium for two years ahead.

All Power Plants have one thing in common - in one way or another, steam is produced inside. This steam further reaches the turbines and spins them so that the motion activates the generator, which creates the so much needed and desired by each of us - the electric current.

And what happens in a Nuclear Power Plant: here the steam is produced by a chain reaction called Nuclear Fission. The Uranium atom is fissioned, which realeases consuderably good amounts of Energy. This energy heats a container of water to a quite high temperature of 312 C. But guess what? The water does not boil because big pressure is applied to it while it is being transported to the steam generator. There the water is allowed to boil and here we go - steam is produced. From here on, all power plants follow the same structure as described above.
Looking a little bit in detail into the fission process, we have to note one thing: once the Uranium atom is split, it becomes into an isotope, which is... radioactive! But this is taken care of - the fission takes place in a reactor, which is surrounded by two walls with vacuum in between. Thus assuring that nothing should leak out of it. But how do we get rid of the radioactive waste? It is packed and carefully trasnported to other countries where the waste is recycled and about 95% of it are sent back to Beznau for further use. Good, right? Still 5% of radioactive waste is there... somewhere..., which will always be a drawback of the Nuclear Fission Method of producing Energy.

The turbines: these 'boring' at first hear structures spin quite fast. They are mounted on the same shaft as the generator, which makes - 3000 rpm (rotations per minute). Just imagine it! Now what is the consequence? This fast speed is needed to induce a voltage on the stator windings. Here it is the fundamental law of physics, which even a social scientist like me remembers: Energy is never produced or destroyed, it is just transformed. In this very moment, kinetic energy is transformed into electrical energy, symilar to what happens in a bike - the dynamo in your rear tire uses the spin in order to give you enough energy for front and back lights. The generator produces 15.5 kV, and the transfomers outside step it up to 220 kV and then send it to the high voltage transmission lines.

And thus I, sitting somewhere in NE Switzerland, am able to write this blog and hopefully make someone else as enriched as I was when I saw all that with my own eyes.

Good job, Beznau!