What is clean energy? How many ways can we generate clean energy?
Good questions. Too many people like to jump on the clean energy bandwagon simply because it has the word “clean.” I mean, do you want to be associated with dirty energy? For that matter, would you want to be a part of anything dirty?
So let’s explore clean energy.
Electricity (aka energy or power) is the movement of electrons through a conductor (wire). How stuff works has a good article that explains the basics of volts, amps and resistance.
The best conductors are named “superconductors” which have an extremely small resistance. Unfortunately super conductors are stiff and must be very very cold in order to work, thus they are expensive to build and operate.
After superconductors are metals. The best conductor is silver followed by copper and gold. Gold has the benefit that it resists corrosion, thus the reason for gold-plated connectors.
Lastly are the semiconductors. These typically use silicon or germanium to produce different electrical effects. The most common is the diode which allows electricity to flow in only 1 direction and the transistor which is an electronic switch, commonly used to amplify a signal.
All large-scale forms of power generation use the same technique: spin big magnets near large copper coils. The movement of a magnet near the coil causes electron flow – electricity. It’s just like an electric motor only in reverse. (In fact if you spin a small electric motor it will produce electricity, too.)
Most power plants use pressure to spin a turbine. The action of the spinning turbine spins the magnets. The differences in energy production revolve around how to make the turbine spin – steam, falling water or wind.
Solar is different in that is uses light to push electrons from one material into the next. The electrons flow through a wire and return to the original material.
Image: “Dampfturbine Laeufer01” by “Siemens Pressebild” http://www.siemens.com – Photo taken with the friendly permission of Siemens Germany by Christian Kuhna
Clean Energy Forms
Clean energy comes in many forms. The most common of the truly clean are hydro, hydro-thermal, wind, solar, solar furnace, wave and antenna.
Hydro-based generators use falling water to spin turbines. Niagara falls, for example, diverts some of the water to a generation plant. The moving water spins turbines. Hover dam does the same thing. This is the most commonly used clean energy source in the world.
Hydro-thermal use naturally occurring steam vents to drive turbines. The steam comes from magma pockets near the surface. As water pours into the pocket it turns to steam. The steam is piped to a plant were it spins turbines. The environmental conditions required for hydro-thermal power make it’s use rare. The only country to use it as a main source is Iceland.
Wind power takes the turbine idea and puts it outside. Large blades are pushed by the wind causing them to spin. Wind power is growing in popularity but is only useful when the wind is blowing fast enough but not too fast. Also the amount of energy produced by a single large turbine is only enough to power a few hundred homes. To power millions of homes requires tens of thousands of turbines.
Solar power uses special plates that generate electricity when struck by light. These panels are usually installed on single location – a home or business. So long as it’s sunny you get free power. But there are drawbacks. Only visible light is useful but that only makes up 7% of the light coming from the sun. Simple things like clouds, trees, fallen leaves and dirty panels significantly reduce the output. And the output is DC but your house runs on AC so a large box is installed to convert the DC into AC (which oddly enough is converted back to DC for all electronics – only motors use AC as-is.) Next to the converter is a large battery that stores extra electricity collected during the day to provide at night. Like all batteries it’s filled with highly toxic chemicals and eventually wears out.
Solar furnace (aka “heliostat”, “central tower” or “solar power tower”) uses hundreds or thousands of mirrors over a large area to focus sunlight on a tower, super heating the liquid inside. Newer designs use liquid sodium or molten salts to capture and hold the heat. Enough heat is captured and maintained to boil water and maintain a boil for up to 15 hours after the sun sets. The largest is the Ivanpah Solar Power facility in California which uses over 170,000 mirrors over 4,000 acres and produces a staggering 390 MW (about 1/3 a nuclear power plant.)
Wave power is something of a new idea. Basically it’s the same as wind except near a shore line and under water. There are concerns that aquatic life could be impacted but the slow movement of the water means slow moving blades. The obvious down-side is slow moving means very little power output. Plus aquatic plants like seaweed would tend to clog the turbines.
Antenna power hasn’t been used but was suggested by Nicola Tesla long ago. The idea is simple: run a wire around a large area numerous times – the more times around (windings) the more power it produces. At the ends you’ll get electricity. Some people like George Noory discovered this when trying to hook up a large antenna for radio transmission. A strong DC-bias* is generated but rather than use this bias, it’s considered a waste product and dumped to ground. However there’s no reason the idea couldn’t be used and the waste energy converted to AC electricity. The down-side is this produces very little power.
*A bias is a constant electrical source (like a battery) that raises an oscillating signal such as an FM broadcast. A bias won’t interfere with the signal but can damage equipment. In stereo amplifiers a DC-bias will cause the sound to become grainy because the bias causes part of the sound to exceed the maximum input level and get cut off.
Mostly-Clean Energy Forms
Nuclear. (Please, people it’s “new-clear” not “new-queue-lar”) Nuclear power uses enriched uranium or plutonium (the “reactor”) to super heat water creating powerful steam that spins a turbine. The steam is cooled in a heat exchanger – much like your refrigerator – and recycled back into the reactor. The water used to cool the steam is convert to steam itself and is released harmlessly into the air. It’s important to note that the water that’s super heated is radioactive – very dangerous but completely contained. The water that’s used to cool the super heated steam is not radioactive. Only heat is exchanged, not radioactivity.
Clean Coal comes in several forms: emissions scrubbers and gasification. Emission scrubbers take the coal burning idea and further process the gasses that are emitted. Things like coal ash and sulfur dioxide (the cause of acid rain) are removed. Gasification is a complex process that converts the coal into a synthetic gas that is much cleaner burning. The process also involves 2 turbines making it more efficient than simple coal burning.
Fuel Cells use hydrogen to produce electricity and water nothing else. This is great for space everything is a pollutant and you can’t have too much electricity or water. The problem with fuel cells is they require a hydrogen source. Currently there is only 2 way to produce hydrogen: electrolysis (breaking water into oxygen and hydrogen using electricity) and chemical reaction
Other forms of electrical generation
Thermocouple is only useful for generating very small voltages and currents. These devices are used anywhere you find a pilot light for a natural gas-based device (e.g. water heater, stove, air conditioner, etc.) The principle is simple: put 2 different metals together and heat them. The result is a small electrical charge. Devices use this charge to keep a solenoid (a special valve) open. If the pilot light goes out, the current stops. When the current stops a small spring in the solenoid pushes the valve closed and gas stops flowing. Thus you can’t accidentally fill your garage with gas when the water heater pilot goes out.
Chemical reaction (batteries) are something everyone knows. There are 2 types of batteries: discharge-only (“primary cell”) and rechargeable (“secondary cell”). All batteries use a chemical reaction to produce electricity. In the case of rechargeable batteries, the reaction can be reversed.
My Take on Power
None of the truly clean power sources is viable to replace coal and oil. They either require too much space, don’t provide enough power or cost too much.
Hydro is the best. All you need is falling water from a waterfall or dam. Unfortunately I think we’ve put power plants on every viable waterfall and dam. There’s definitely a limit here unlike solar.
Wind is good when it’s windy, but not too windy. I’ve seen the wind farms on I-10 East of Riverside, CA. Hundreds of turbines of various sizes consume enormous amounts of land, out into farm lands. It’s quite a sight for a few miles then it’s repetitive. Of the few times I’ve past only a few of the turbines were ever active. And the one time I saw most of them active there was still a fair percent sitting idle.
Solar is great for places that get a lot of sun and only on a residence-by-residence basis. For example, don’t sell solar in Seattle, WA. On the flip-side, there are a few businesses that use solar in an innovative way: as shade for parking lots. They generate electricity to offset building power while keeping your car nice and cool.
Solar furnace is a desert power generator. Like wind, it consumes enormous amounts of land, though unlike wind, can’t be added to farms. It’s also like solar in the it only works when the sun is out. Sure, newer technology continues to supply power for up to 15 hours after usable sun light, but if it’s cloudy the next day you get nothing.
We should be using nuclear power! In the USA, the IFR reactor proved that it can be safe and far more clean than the existing nuclear power plant designs. A good example is France. They get 80% of their power from nuclear plants and 0 problems have occurred.
Need more proof? The IFR power plant was designed so that any failure results in a clean shutdown. That means 3-mile island, Chernobyl and Fukushima can’t happen. Literally they can not happen. The IFR reactor is also able to reuse spent nuclear rods meaning it produces only 1/4 the nuclear waste of traditional nuclear power plants. Also the IFR can burn nuclear waste from those other power plants.
IFR: Here’s a video.
Let’s get a few facts straight. Here are the radiation-related death counts from recent nuclear disasters:
- 3-mile island: 0
- Chernobyl: 50 + up to 4000 workers (over 100,000 people worked on cleanup)
- Fukushima: 0 (over 130,000 people worked on cleanup)
- 1 pound of nuclear material produces as much energy as 5,000 barrels of oil.
- Some few nuclear plants have been designed and built to withstand the direct impact of light aircraft.