Turbines 8/10/21

Science with Richard Bleil

The other day I saw a headline exclaiming “largest wave turbines begin generating electricity.” Or something to that effect. Was the article actually about this? I don’t know. It was one of those sites that requires you to register, and I avoid those sites but only like the plague. But, neither does it seem like it was a ruse.

Funny word, ruse, don’t you think? Sounds a little like “rose”, or even “rouse”, but no, it means con. That has absolutely nothing to do with this post, but I like pondering words that just sound funny sometimes. Like “sanction”. I read about attorneys being “sanctioned” by a judge today (as of the writing of this post). I really don’t like that word. To be “sanctioned” can mean, for example, to be given license to some activity that is otherwise unacceptable. “Sanctuary” is where you cannot be touched, such as turning to a church to seek sanctuary from legal authorities. In this article, “sanctioned” meant that they were reprimanded. How can one word have such disparate meanings? It’s just crazy. Welcome to the English language.

Anyway, back to the point. See, electricity is conceptually very simple to generate. A “wave turbine” is very similar to wind turbines. In either, water (in wave) or air (in wind) flow past propellers, causing them to turn. These propellers, then, turn a coil of wire (or a magnet) in a magnetic field (or around a coil of wires). As the wires cross the magnetic force lines, it generates alternating current. This is, in fact, why current is usually alternating, since if it cuts the force lines (for example) to the right the current flows in one direction, but in the opposite direction as it cuts the force lines (in this example) to the left.

It’s that simple. Find a way to keep the wire coil turning and you generate electricity. The faster you turn the coils, the higher the frequency (standard American electricity is at 60 Hz, or sixty rotations of the coil per second). The more coils in the wire (with a strong enough magnet) and the higher the voltage. In America, electrical current is (about) 120 volts. But literally, anything that can keep those coils turning will work to generate electricity. If you can come up with a novel way to do so, you too could earn enough money to waste on a flight into space.

In coal or oil burning plants, or indeed even in atomic or nuclear power plants, the concept is the same only it’s super heated and high-pressure steam turning the turbines. The heat from burning the fossil fuels or the decaying nuclear core heats water in the boiler causing a great increase in pressure. This steam, then, is directed past the turbine when enough pressure exists to turn it at the desired frequency. Hydroelectric power runs water through a damn with very high pressure again turning that turbine. It’s all basically the same.

Direct current is another story. In direct current, electricity flows from the anode to the cathode. In a battery, for example, the electricity results from a controlled chemical reaction. Chemicals at the anode want to lose electrons, and those at the cathode want to gain them. This is called a “redox” reaction, meaning some chemicals lose electrons (are oxidized at the anode) and some gain the electrons (are reduced at the cathode). As long as there is a current connecting the two sides the reaction will proceed. The shortcoming of this as a power source is that, eventually, the chemicals will run out and the battery will die. Rechargeable batteries can have this reaction reversed basically by forcing current in the opposite direction. This regenerates the chemicals at the anode and the cathode so it can again hold a charge (but thanks to the second law of thermodynamics we can only do that so often). Unfortunately, though, it will always take more electricity to regenerate the chemicals than they will return to us (again, the second law) which is why, as amazing as recent advances in battery technology have been, a battery will always be little more than an electrical storage device.

Solar power does, indeed, also create direct current. Of course, this has a special problem because our electronics are all designed to run on alternating current. This means that the direct current is often run through a DC/AC converter so the DC current can be used in our AC devices. Still, I think solar power must be one of the most unique forms of generating electrical current.