Fresh Air Matters... with Capt. Yaw
'Don't put your hand in the lake, it may kill you!', I heard a young lady, probably in her early twenties, say to her friends on the shores of Lake Volta. I was so happy that she may be aware of Schistosomiasis - but then my heart sank, and I shook my head, as she added 'It is full of electricity and electricity can kill you.' I asked for an explanation. 'The teacher told me that Ghana gets its electricity from the lake. So it is dangerous. Don't touch it.'
Is it the teacher or is it the student who got it wrong? Is it a misunderstanding of the term Volta? Perhaps it is all three!
I have been truly surprised at the number of people who simply do not understand how electricity is generated - regardless of the power source. Whether you use hydroelectric power, an internal combustion engine genset (super or diesel powered), light crude oil, Liquid Natural Gas (LNG), natural gas, coal, wind or wave power to generate electricity, the basic mechanics of electrical power production are the same. (Solar is different, but we will come to that later).
Less than two hundred years ago, Michael Faraday discovered that you can create an electric current by moving a magnet through a copper wire coil - or a copper wire coil over a magnet. This led to whole change in the world - electric power became something we could 'create and control'. Yes, that was less than two hundred years ago. Of course, the usual naysayer and stick-in-the-mud crowd put him and the whole thing down. 'Why would anybody want electricity? There are oil lamps and... well... what on earth could it be used for?' It is certain that others thought such a thing was 'magic' and even 'ungodly'. That, I am sad to say, has been the reaction against almost every advance in mankind's development. Fortunately, others started to work with the same concepts - often coincidentally - and the 1800's were the years of electrical discovery! By the end of the 19th century, Tesla amongst others had allowed their imagination and creativity to flourish - without constraints - and the reliable, stable generation of electricity by the rotary motion of magnets / copper coils, had seeped into every crevice of the developed world. The electric motor and electric generator have turned the world ever since!
You too can create electricity - not a lot, but some: Look around the house for a standing fan and a multi-meter or voltmeter (you need one that measure small voltages). Unplug the standing fan and put it outside in the wind. Change its direction until the fan blades are turning in the wind. Now, with the fan still UNPLUGGED (ask an adult who understands to help you!) put one of the multi-meter/voltmeter probes on the 'live' pin and the other on the 'neutral' pin of the plug (make sure that it is still UNPLUGGED!) You will see a small voltage being generated on the meter's readout. Yes, you are creating electricity using a fan. HOW? The fan has an electric motor, which is pretty much the same (but not nearly as efficient) as the generator coil attached to the engine of your genset, the turbines at Akosombo or a gas turbine at a thermal plant - it is the very same principle as the wind turbines... Yes, you have demonstrated a small wind turbine! The electric motor has magnets and copper coils moving against each other. (one moves - the rotor, and the other stays still - the stator). As the they move past each other (they do not touch) the magnet, in effect, 'drags' electrons off of the copper atoms and pushes them to the next bit of copper - as it spins they are pushed along the wire - and that is all that an electrical current is - lots of electrons moving along a wire.
How do we get electricity from each of the power sources mentioned above?
Hydroelectric power: a dam creates a head of water (the water behind or 'above' the dam is higher than the water after or 'below' the dam). The bigger the difference in height, the greater the head and the more 'force' of water you have. Allow that water to pass through a turbine (basically a big fan or series of fans), and it can turn with a great deal of force and speed. Connect the axle of the turbine to a generating coil (like that electric motor in your standing fan), and it will create a lot of electricity! The water DOES NOT contain electricity for direct transmission to the power grid! No, we use the POWER source of the water to turn a turbine which then rotates a massive electrical generator coil (copper coils and magnets) and THAT is what creates the electricity - basically the same magnet and copper wire coil that Faraday demonstrated in the 1820s!
The internal combustion engine genset (super or diesel powered) is easier to understand now. It is just an engine - the same as in your car or tro-tro with an electrical generator attached to the output end. So, instead of turning the wheels of the motor-vehicle it is turning an electric generator to produce electrical power. (take a look, and you will see a unit bolted to the end of the motor with wires coming out of it - that is the electrical generator, not the engine!)
Light crude oil, LNG, natural gas, etc. can be burned on injection to the turbine and the hot (about 1000°C) gases turns the turbine (an engine, but not with pistons, rather with blades that turn similar to an aircraft jet engine) that rotates fast - and that is connected to the electric generator... These hydrocarbons are POWER sources (not ELECTRICAL power, but a power than can be USED to CREATE ELECTRICAL POWER), and can also be used in the same way as coal...
Coal is one of the 'dirty power providers'. Generally, it creates more carbon and sulphur emissions than the other power sources. Many countries are moving away from coal because of this. However, coal was used for many years, and is still used in many countries, to heat water (just like a big kettle). By using the heat from burning coal to boil water, the steam can then be used to turn turbines that are provide rotary movement to the electric generator, thus producing electricity.
Wind power is as simple as the experiment with the standing fan. The wind turns the blades of the wind turbine, which has then turns the electric generator. Generally a wind turbine has two or three massive blades which are turned into the wind and then rotating, allowing it to convert the wind into a rotary force that turns that electrical generator!
Wave power simply moves magnets and coils against each other - the way we know how to produce electricity. Either the tide is used to turn a turbine (which works well in certain places) or by using the 'up and down' motion of the waves. Although a lot of talk about wave power has been around for while, we still see very few projects implemented. It is certainly a power source to watch in the future as we build on our two hundred year heritage of electricity!
What about Solar? No moving parts. No magnets. It does use copper wire, in order to transmit the electrical current, but not to produce it. Imagine two thin layers of silicon. Each layer is made to behave differently by adding something to it. We make one layer 'negative' or n-type, which can be done by adding (called 'doping with') phosphorus, and the other layer can be made to be 'positive' or p-type by doping with boron. When sunlight hits this, it makes the electrons run around between the two layers - and some escape to our waiting copper wires - and thus an electric current flows. OK, it is a bit more complex than that, and there are other doping options, ways of putting it together, etc... but you should get the idea.
Of course, there are other POWER sources for electricity, but just remember that the vast majority of our mains electricity is generated by the moving of magnets and coils of copper wire! Finally, look under the bonnet of car... you will see an alternator - look carefully, you will see a 'fan belt' that is used to turn the alternator when the engine is running - to generate electricity. The electricity produced is used to charge the battery and produce all the electrical current needed to run the engine, lights, radio, electric windows, GPS, etc... Just remember that 200 years ago, electricity production was not an option! Now, look around you and imagine a world without electricity!
Capt. Yaw is Chief Flying Instructor and Chief Engineer at WAASPS, and Pilot/Engineer with Medicine on the Move, Humanitarian Aviation Logistics (www.waasps.com www.medicineonthemove.org e-mail firstname.lastname@example.org)