This is my first post, dont really know how this works but i have a question…
Say you have a big generator, one that is capable of powering a house. can you charge that big one with a bunch of other smaller ones? So, you charge smaller ones, then hook it up the big one and charge it whenever needed.
I am not a generator expert but every generator I’ve seen runs on some sort of fuel (gas, diesel or propane). There’s no “charging” involved.
from what ive read/watched… a generator takes mechanical motion and turns it into electricity. the motion is done by a rotating turbine, and can be powered by gas/diesel/propane, like youre saying. but what im wondering is can you charge (gas OR pedaling OR wind etc.) a few smaller generators fully, then hook them up to one big one?
Are you asking if the electrical output from a number of small generators can be combined at at larger generator before connecting that larger generator into the power grid? I don’t see why not, but you would need to jury rug something to use the larger generator as a distribution board.
Oh, and a generator that is taking electricity in is called a “motor.”
right! thanks. what do you mean by distribution board? i have this project for a design class, and my idea is a sustainable gym. so people come and work out, like any other gym, except, resistance is provided by powering up a generator instead of using weights and cables. so basically a row of stationary bicycles, say 10 will all be placed side by side, with the axis of the rear tire aligned, and they are all charging a generator at one end. bench press, squat rack, rowing, everything will be hooked up to generators. im just wondering if these generators would need to be hooked up to a larger one which in turn powers the room/building itself? i am just in the beginning stages of this idea, obviously, and i would like to develop it, and as you can tell, im not a science buff
No, the individual generators should not be connected to one big generator. They should be connected to a battery to store and distribute the electricity.
gotcha. thanks
Yeah, you are talking about batteries for storage and not generators. You could have any number of small generators feeding into a battery or bank of batteries. You might be disappointed with the cost-benefit analysis however. Humans don’t produce much power even when they are working out. There is also inefficiency in converting that human power to electricity and then converting it back to useful energy again.
If you are talking about typical modern AC generators, there’s no need to hook them all up to one generator to “condense” them. You just hook them all up in parallel and each generator supplies what power it can.
When you hook generators in parallel, not only do you have to get the voltage and frequency identical, you have to get the phase (where it is in its sine wave cycle) identical as well, otherwise you generate some rather huge electromotive forces when you throw the switch to connect them and the generators you are trying to hook up can fail rather spectacularly. Fortunately there are things called synchroscopes and phase lights that make fairly easy to figure out when they are exactly in phase (or close enough).
Once you have generators in parallel, they naturally run in lock step. If you remove power from one it doesn’t slow down. Instead, the other generators will send power to it making it act kinda like a motor. You also can’t speed one generator up just by adding more mechanical power to it. Instead, all it does is supply more electrical power to the line.
This is how modern power plants work. A single plant may have many generators, and they will all be tied together to connect to the power transmission lines. Power systems are all interconnected like this as well, except that you’ll have transformers raising the voltage of the lines between generator plants and such, but it’s still the same basic idea.
Also, there are things called motor-generator sets, in which you do have a motor connected directly to a generator. In the old days, they were used to tie systems of different voltages or frequencies together. We also had a few of them in college which we used to simulate things for classes and research.
For the specific task that you are attempting (connecting exercise machines together to generate power) you’ve got a couple of different problems. First, the people using these machines are not going to want them all to spin at a constant speed. Instead, each individual is going to want to be able to spin their machine at their own rate, a rate that will vary quite a bit during their workout. This means that you are probably best to go with DC generators and tie them all into batteries, with diodes preventing the batteries from back feeding into the machines.
I don’t know what you plan on doing with all of this electricity, but another problem you are going to run into is that humans aren’t very good at generating power. Each human will only generate maybe 50 to 100 watts, barely enough to power a couple of light bulbs in your typical living room lamp. In other words, it’s not much power. A microwave oven or a hair dryer is going to require much more power, somewhere around 1500 watts or so. Basically, a very physically fit human would have to exercise for an hour to get 4 minutes worth of electricity for their hair dryer (if I did my math right).
If you just want resistance for the machines, then all you need is literally resistance. Instead of a generator, just hook a variable resistor up to a motor and have the machine try to spin the motor. The lower the resistance, the harder it will be to turn the motor. All of the electricity you generate will turn into waste heat in the resistor, but it has the advantage of being a nice easy simple system.
These types of machines already exist, by the way, so if you think you are inventing some whiz bang new idea someone else already beat you to it.
Like engineer_comp_geek pointed out, you’re just not going to get enough output from human driven machines to power your gym. Even with highly efficient generation schemes your participants aren’t going to give you enough power to light, heat, cool, operate your gym.
Some newer exercise equipment is designed to power itself. That is, the displays, logic, cooling fan etc are powered by the use of the operator. That’s probably the best use for the human output. No external connects or batteries.
Using battery storage, inverters, converters etc to put AC power back into the facilities electrical system would probably not pay off when weighed against the added cost of batteries, control and electrical protection systems. An electrical protection system is something that your local utility would insist on having so that your 120 volts of pedal power doesn’t backfeed through a transformer and zap one of their local workers during a power outage. The power system is designed for them to turn the power off on their end during an emergency and they are going to want assurances that your power will stop flowing too.
If you really want to go through with some kind of a human excess energy theme you might consider designing equipment that outputs DC power and channel that excess power to a supplemental electric water heater (a preheater for the gym’s hot water shower system). A simple heating element can handle a wide range of voltages and current and would save money on water heating bills. As it would be on a dedicated circuit you wouldn’t have to invest in a protection system for the utility. And since you’re storing the waste energy as heat you wouldn’t need to buy and maintain batteries.
Welcome to the SDMB, le_robert. We have different forums for different kind of questions. Those with factual answers, like yours, go in General Questions, so I’m moving it there for you. MPSIMS, where you first placed it, is basically our “miscellaneous” forum.
Again, welcome – I hope you find other things of interest as you look around our forums.
twickster, MPSIMS moderator
For AC generation, you can run multiple generators in parallel without them turning in lock step. You just have to use asynchronous generators. Ordinary induction motors work as asynchronous generators. Turning one of them a little faster makes it deliver more power to the system. To do this, you do need capacitance in the system, and it may be helpful to have one big synchronous generator in the system.
Or you could use the power grid as an alternating current battery. Turning an induction motor “too fast” pushed power into the grid and makes your electric meter run backwards.
A typical small car battery can supply 40 amp-hours. So you can say that it can provide 2 amps at 12V for 20 hours. Or 24W for 20 hours.
A typical generator can provide 800W continuous for around 8 hours with approx 1 gallon of fuel. That is approximately 320W for 20 hours.
If you are looking for bigger bang for your buck (for backup power purposes) invest in a nice generator.
As to powering a house with a treadmill - you are joking right ?
You don’t charge generators, you operate them and they produce electrical power. You can use generators to charge batteries, which store electrical power. Understanding and using the terms correctly will help you get accurate answers to your questions and will allow others to understand your project.