admin answers:

Electric motors produce mechanical power from electrical power. If the power is 1hp, the power is 746 watts. The motor needs more than 746 watts of electrical power to produce 746 watts of mechanical power. However it only produces 746 watts of mechanical power if it is driving a load that needs that power.

The motor bike spark plug may require 10-15000V certainly, but that is not electrical power, it is only voltage. Electrical power has 2 components, voltage and current. The current in the spark may be only 2 milliamps. Thus the peak power is 10,000V x 0.002A = 20W. Additionally that is only for a brief part of the time. There is just one spark every 2 revolutions of the engine, maybe 25 sparks a second, so a spark is a small percentage of the time. The energy (in watt-seconds) is very small.

If the motorbike has a battery, it is charged by a small generator on the motorbike. This is 6V or 12V battery, a far more suitable source of power to drive an electric motor. However this battery would usually be too small for a 1 or 2 hp motor.

Working out the power for the motor, lets say 1000W of electrical power is needed to produce 746W (one hp) of mechanical power. With a 12V battery the current = 1000W / 12V = 83A. You need a battery that can deliver 83A per hp for as long as you wish to run the motor. You need something to charge that battery. An 80Ah battery would run for 1 hour in theory, but more like 20 minutes in practice. You would use a higher voltage and bigger battery for better efficiency, maybe a 24V battery and motor. It is possible to charge this battery using solar panels or a home generator. However it is more efficient (cheaper) to run the suitable motor directly from the generator, than to use the generator to charge the battery and run a motor.

You are asking a lot of questions, good to learn, but you should explain the big picture, what you actually want to do. What is the motor for? How long to run? What power source is available? Power from electricity suppliers is usually the cheapest.

admin answers:

The big “hidden” problem with wind and solar power generation is that we can’t store electricity in the amounts necessary to keep everything going when the wind stops or sun goes down. This means that when the wind stops blowing or the sun is hidden by clouds (or at night), some other means of production of electricity has to exist. We cannot run cities and factories on batteries charged when it’s windy or when the sun is shining. This means that EITHER we have to maintain the “old, polluting” systems such as coal, gas, water and nuclear OR we have to DO WITHOUT through rationing via brownouts, blackouts, use restrictions, etc.

Assume that you live in an area that uses 1000Mw of power. Right now, you have two coal fired plants and a hydroelectric plant (dammed river & generators) to produce the 1000Mw needed. Joe Thompson, billionaire, decides to start a wind farm. At peak capacity, his 1000 wind turbines produce 500Mw of power. So, when the wind turbines are running at full capacity, one coal plant can be shut down and the other can go to 75%. This allows for 1000Mw of power to be fed to the electric grid. Without shutting down the coal plants, there would be more electricity on the grid than demand, which is a no-no.
Now, the wind stops for a few days. The coal plants kick back in and go to 100% production to maintain the 1000Mw on the local grid.

Since the coal plants are unable to be profitable at 0% and 75%, the owners of the coal plants shut them down and stop producing. The hydroelectric and wind production are all that remain. Joe Billionaire builds enough wind turbines to replace the coal plants (while the wind is blowing). Everything is green, until the wind stops and the amount of power available drops to 0 (or whatever the hydro plant is producing).
Then, everything stops and everyone is in the dark.

Power supplies HAVE to be stable. Nuclear, Coal, Gas, and hydroelectric have been and can continue to be stable steady suppliers. Wind and solar will ALWAYS be temperamental and will require backup production by the sources they’re supposed to replace. If those backup sources have to be maintained, the price of electricity from “free” wind will skyrocket. Having idle power facilities is like having a Ferrari in your driveway as a backup car for when your Prius breaks down. It still has to be washed, insured, and paid for, but you get nothing out of it. Eventually, you get rid of the Ferrari. Then your Prius breaks and you walk.

admin answers:

I think the only down side is that no electricity is generated at night.

As for other answer mentioned energy used to produce panel, here is a interesting fact:

The energy payback time (i.e., the time it takes for a PV system to generate the same amount of energy that it took to manufacture the system) for PV systems is 2 to 5 years. Since a well-designed and maintained PV system will operate for more than 20 years, and a system without moving parts will operate for close to 30 years, PV systems produce far more energy over their useful life than we use to manufacture them.

admin answers:

Nope. The only solar power that works adequately all through the night is solar therm. The sun’s heat melts salt. The molten salt boils water, water produces steam drives a turbine connected to a generator. Since the salt gets VERY hot and takes a long time to cool down a MSR solar therm reactor [as opposed to a MSR Thorium nuclear reactor] can operate all night long.

An offset is a financial instrument – it is like a stock certificate; it is in fact a commodity forward and the commodity is electricity. It allows you to spend credits produced in generating solar power on electricity generated from the grid. In this case you are not generating energy from the solar cells but from some other electricity plant. You are just getting your electricity for free by spending your offsets.

Not sure but I think a hospital will require large amounts of electricity – too much for solar cells to produce????

admin answers:

The electric utilities can’t hold us hostage the way the petroleum companies do – because you have more choices with electricity.
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If electricity prices get too steep, you can put up your own solar panels, or your own windmill, and make your own electricity. Or you can go to Home Depot right now and buy a generator that makes electricity from a natural gas hookup.
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Sure, solar panels and windmills are expensive, but you’d do it if you got mad enough at your electric bills. Utilities would be nuts to let prices get high enough for this to happen.
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Right now, electric utilities love the idea of electric cars. For the first time, they have people willing to buy electricity in the middle of the night. My own utility (here in Michigan) gave me a free electric car charger for my garage, and a special half-rate for overnight charging.
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Here’s a study that shows there’s enough electricity available overnight for nearly everyone to switch to electric cars:
http://www.sciencedaily.com/releases/2006/12/061211221149.htm

admin answers:

You could certainly do some physics experiments with sound waves:

– Resonant frequencies of open and closed pipes, as a function of length. Can use cheap (black ABS plastic) pipe, at the plumbing isle of a Home Depot store.

– Resonant frequencies of guitar strings as a function of length, tension, mass of string.

Resonant frequencies of a cavity like a hollow-body (acoustic) guitar or violin. Compare how “harsh” the violin string sounds alone (without wood body), vs. The much more pleasing sound when the string’s harmonics are filtered by the resonance of the hollow-body.

– Resonant frequencies in a room in your house. There are multiple resonant modes, in a room with parallel walls, closed door. These are “standing waves”, so by moving the microphone to different points in the room, some points will have maximum intensity & other points will be a “null”.

Gadgets to use – Resonances: Use a variable-frequency sine generator, audio amplifier, speaker to generate the frequencies.

Gadgets to use to observe frequencies of guitar strings: You could use an oscilloscope and microphone to measure frequency. Can also observe harmonic structure of sound (shape of waveform, vs. Sinewave, as observed on an oscilloscope).

There are many possibilities. I’d recommend reading an introductory book on “musical acoustics”. For example, Chapters 1 of “Master Handbook of Acoustics” by Everest ($ 20), explains the basics of sound waves.

Note: As you compete in science fairs in subsequent years, you can continue to expand your investigation of sound waves to increasing levels of sophistication.

-> For example, you can investigate properties of human hearing — how our binaural hearing can determine the distance and angular location of a sound source. Ben Burtt at Lucas Film did pioneering work in this field, to create the 3D “soundfields” in the original Star Wars film.

-> As another example, you can investigate the relationship between construction techniques used to build violins, and subtle changes in the sound produced by the best violins.

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admin answers:

Coal is primarily used as a solid fuel to produce electricity and heat through combustion. World coal consumption is about 6.2 billion tons annually, of which about 75% is used for the production of electricity.[citation needed] China produced 2.38 billion tons in 2006 and India produced about 447.3 million tons in 2006. 68.7% of China’s electricity comes from coal. The USA consumes about 1.053 billion tons of coal each year, using 90% of it for generation of electricity. The world in total produced 6.19 billion tons of coal in 2006.

When coal is used for electricity generation, it is usually pulverized and then burned in a furnace with a boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines which turn generators and create electricity. The thermodynamic efficiency of this process has been improved over time. “Standard” steam turbines have topped out with some of the most advanced reaching about 35% thermodynamic efficiency for the entire process, which means 65% of the coal energy is waste heat released into the surrounding environment. Old coal power plants, especially “grandfathered” plants, are significantly less efficient and produce higher levels of waste heat.

The emergence of the supercritical turbine concept envisions running a boiler at extremely high temperatures and pressures with projected efficiencies of 46%, with further theorized increases in temperature and pressure perhaps resulting in even higher efficiencies.[8]

Other efficient ways to use coal are combined cycle power plants, combined heat and power cogeneration, and an MHD topping cycle.

Approximately 40% of the world electricity production uses coal. The total known deposits recoverable by current technologies, including highly polluting, low energy content types of coal (i.e., lignite, bituminous), might be sufficient for 300 years’ use at current consumption levels, although maximal production could be reached within decades (see World Coal Reserves, below).

A more energy-efficient way of using coal for electricity production would be via solid-oxide fuel cells or molten-carbonate fuel cells (or any oxygen ion transport based fuel cells that do not discriminate between fuels, as long as they consume oxygen), which would be able to get 60%–85% combined efficiency (direct electricity + waste heat steam turbine).[citation needed] Currently these fuel cell technologies can only process gaseous fuels, and they are also sensitive to sulfur poisoning, issues which would first have to be worked out before large scale commercial success is possible with coal. As far as gaseous fuels go, one idea is pulverized coal in a gas carrier, such as nitrogen. Another option is coal gasification with water, which may lower fuel cell voltage by introducing oxygen to the fuel side of the electrolyte, but may also greatly simplify carbon sequestration.

I hope i helped…

admin answers:

Could it be imaginable, that Saturn is a generator for the sun?

No. If it were as you say, then it would be igniting other bodies also in the solar system (including Earth).

A very suitable and testable explanation for the production of energy in the Sun was already proposed in the early 20th century by Arthur Eddington. If you have an alternative, testable explanation, then please describe it so that it can be tested. Http://www.youtube.com/watch?v=b240PGCMwV0#t=0m37s

How can we know exactly what’s inside Saturn?

“Exactly”? We can’t.
But you can look at what happens in the parts we can see (above the surface) and compare with predictions of what would be expected for different kinds of things in the deep. Http://www.youtube.com/watch?v=b240PGCMwV0

Read this: http://en.wikipedia.org/wiki/Saturn#Internal_structure
and follow the links there.