power reading in novelty generator system

[charland]

I have an application where my customer wants to have a "Green" musical event. The idea is that there will be a number of cyclists generating power with some kind of meter reading the power generated and then comparing it to the amount of additional power taken from the grid. I want to know if there is an easy way to measure the power from the grid (off of two power lines, 15A capacity) and then measure the power coming from the bank of cyclists. Ideally I would like something that could plug into a laptop and perhaps display on a program like Excel. My plan is to use three ammeters, two for the grid power (120 VAC, one per line) and then one on the power going into the battery bank from the cyclists (12 VDC). By using some simple equations I could quickly display both of the power rates.

question 1 - is there a commercial system with software that can be used for this? Assuming a normal PC laptop with windows and office.

question 2 - can I wire ammeters with a voltage output in series (to add the readings for both currents from the grid power)?

Thanks
Charlie Harland

 

[Skogsgurra]

My biggest concern is: How do you add power from the bikes to power taken from the mains? Do you plan to rectify mains power (after transformer) and feed it to a battery? And also rectify bike power (probably no transformer needed) and feed to same battery? What kind of generator will you use on the bikes?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[charland]

I want to keep this as simple as possible considering our customer doesn't have much funding and they are only looking to make a simple statement about energy awareness. My plan was to provide a box with electrical outlets. Say 9 in total (all standard 120 VAC, 15amp) 4 from power provided from the first grid circuit, 4 from power provided from the second grid circuit and one from power provided from the inverter in the cyclists' circuit. It would then be up to them to plug things in appropriately to keep the right amount of loads on each circuit. This way I never have to combine the two power sources. They indicated that they would like a couple of the lights to be powered by the cyclists so worst case scenario, some of the lights go dim mid concert.

As for the generator, I prefer using an alternator because of the availability and the built in voltage regulator.

 

[roydm]

The power from the mains you can read with a simple ammeter (assuming your lamp load is incandescent). You only need to measure 1 wire.
W = A x 120
For the cyclist you can measuere DC Amps and will need to measure Volts (unless that's regulated) for Watts
There will be some loss in the inverter but you should be able to just factor that into your calculation.
W = (A x V)+ inverter loss
If you want to input into a laptop there are plenty of transducers available that will do that for you.
Regards
Roy

 

[Skogsgurra]

Have a look at the LabJack gang. Small, cheap, USB powered. But one common gnd terminal. So probably difficult to use if you do not want to connect the different circuits together.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[OperaHouse]

An exceptional athletic person can produce about 150 watts. Unless everyone in the concert is on a bike, the concept is totally bonkers. Even then it would be quite expensive to do. Sorry, but if you have to ask this question there is no way you can pull this off. There are just too many technical issues.

 

[charland]

Hi OperaHouse,

No doubt. This will be a statement for the purpose of discussion. Similar to the way that the recent Earth Day "lights off" hour had no real impact on Green House gases but still caused dialogue. We're counting on 50 W per person as we expect out of shape people and eight year olds to play along as well. I just wanted to know of any good instrumentation systems that could be used to monitor the relative power inputs, that could be read by a laptop and then manipulated with a program like Excel.

 

[OperaHouse]

The real question is where are you going to get the bike generators? Building a number of these is a project in itself and they all have terrible mismatches between the generator and the battery resulting in a loss of more than half the power generated. Good intentions does not replace a sound technical design. I often visit RE sites and the waste of energy by these people drives me nuts. They work so hard to generate it then they just throw it away! I have a summer home that is off the grid and it only uses 300W/H a day.

 

[roydm]

Generator (Alternator actually) idea
Get old bikes
Remove back tires
Replace with belt driving auto alternator
(wire alternator field directly to output, without regulator. As previous poster pointed out you are limited to about 10 Amps / person.
Isolate each alternator with a diode to prevent backfeed into field.
You would need to allow for power going to field.

Use 12 Volt lamps, not 120 this will avoid having to use inverter.

Q) Do you really need a battery, that's just extra expense and complication. Granted it would clamp the maximum Voltage.

Roy