Why are sports clubs (gyms) are load, not generator, on the grid?

[EnumaElish]

Wouldn't an extraterrestrial looking at the sports clubs think that people must be working hard to supply electricity? That they are running on giant dynamos?

But isn't the reverse true, that sports machines consume, not generate, electricity?

Is it merely a symbol of affluence (that is, another case of private benefit vs. social cost)? Or is there a cost/benefit analysis that would justify the direction of the flow?

 

[Danger]

You know, dude... I think that you have one hell of a good idea there. If all of the equipment in a typical commercial gym could be outfitted with generators, it would significantly lower the outside energy consumption of the facility. I can't see it being enough to cover all needs of the building, but is should certainly offset the amount needed from the grid.

 

[russ_watters]

The only piece of equipment I know of that generates electricity is the bikes and rowing equipment. It would be a pretty complex (not to mention expensive) undertaking to design other equipment to generate electricity.

 

[wxrocks]

Yeah -- running to generate electricity would give an odd running stride. But I could see bikes, stair climbers, ellpticals, all generating. Your weight machines could also use a magnetic resistance instead of actual weight and generate electricity (like a hybrid car).

You could go further and capture excess heat from saunas and hot tubs and maybe get something out of it -- but I don't know how cost effective it would be.

 

[Janus]

We had a simular discusssion some time back. After factoring in losses, it probably works out that the energy generated by a person on a treadmill or other piece of exercise equipment would barely generate enough electricity to run a 100 watt bulb for that same time. Or put another way, they wouldn't even provide enough electricity to heat the hot water they'll use when they take the shower they'll need to wash off their sweat.

It might put a small dent in the Electric bill of the Gym, but after the expense of installing and maintaining the generating equipment, it would be a long time, if ever, before it paid for itself.

 

[Danger]

Are you sure about those figures, Janus? I know of some people who hooked generators to stationary bikes so their kids would have to excercise in order to watch TV. I seem to recall that they got about twice as much watching time as they spent pedalling, which would indicate an output of around 200 watts. Those were fairly sedentary little yard apes, so I would expect that fit adults pushing themselves should be able to do a lot better.

 

[AlephZero]

This link suggests 200-400 watts is about as much as you will get as a long term average. The peaks output is a lot higher. http://cadlab6.mit.edu/2.009wiki/index.php?title=Human_output_in_variety_of_situations

It would probably be cheaper to put a solar panel on the roof than modify the equipment, considering sunlight can generate up to 900w/m^2.

In any case, all the energy is converted to heat for free, so the power required for heating in winter is reduced already!

 

[wxrocks]

Well, there could be some truth to the heat thing as well -- You know the Mall of America has no heating system. It is heated by body heat and the waste heat from the resturants is exchanged back into the mall itself. So perhaps we should look at the gym of the future as more efficient by thinking of some of these things.

 

[FredGarvin]

The heating aspect is really the only thing I think you would get on the plus side of the energy balance. It doesn't take very many bodies working out to create enough heat. We keep the thermostat quite low in the winter during our workout classes.

 

[EnumaElish]

Installment and maintenance are sunk investments -- they are there regardless, and do not matter when deciding the type of equipment being installed. Put differently, they are not asset-specific investments, where the asset is a sports machine of type "L" (Load) or a sports machine of type "G" (Generator). So, installment and maintenance are not part of the cost/benefit analysis for the specific purpose considered here.

Saying that the amount of electricity is small may be missing the point. Right now each sports machine is a positive load. Even if each machine were to break even in terms of energy consumption (net consumption = zero), it would be a net gain; because it would take some load off the grid.

I see Russ's point about R&D costs; are we stuck in another type of "VHS tape" or "Qwerty keyboard" phenomena (an inefficient solution too expensive to reverse)?

 

[Q_Goest]

I'd have to agree with Janus. From what I've seen, the average person isn't going to generate more than 100 watts, but for the sake of arguement, let's make it 200 watts. That's 1/4 hp, quite a bit to maintain for any significant amount of time for the average person.

Now let's say the bike has a 50% utilization rate over a 10 hour day. That's 200 watts for 5 hours, or 1 kw hour. That amount of energy is worth about $.07.

In a year (365 days) that's $25 worth of electricity.

Note also the time the generator is spinning is about 1800 hours. A typical low cost generator isn't going to last more than 2000 or 3000 hours, so you need a much better, industrial grade generator to get the 50,000 hours you'd need to make it worth while. They'll be much more expensive.

For $25 a year, you're looking at something on the order of 20 year payback (about 36,000 hours of operation) without considering interest. There are much better ways of spending that money.

Fred said: The heating aspect is really the only thing I think you would get on the plus side of the energy balance.

And that's exactly right. The amount of heat energy during the winter is going to have considerable value. That energy is taken out of the room as electricity where it could otherwise be used as heat. That pushes the payback period out much farther than the 20 years.

 

[brewnog]

Setting aside the cost issues (and back-of-envelope calculations show me that the juice just isn't worth the squeeze), it'd be a technical nightmare to set up things like treadmills and rowing machines to supplement the conventional power supply in terms of frequency synchronisation. You'd just never get it to work.

Turn off some light bulbs instead, that'd be far more beneficial. Or cancel your gym membership and go cycling in the park instead.

 

[russ_watters]

Installment and maintenance are sunk investments -- they are there regardless, and do not matter when deciding the type of equipment being installed. Put differently, they are not asset-specific investments, where the asset is a sports machine of type "L" (Load) or a sports machine of type "G" (Generator). So, installment and maintenance are not part of the cost/benefit analysis for the specific purpose considered here.

That is only true if the cost is close to the same, and it clearly would not be for anything other than the machines that already have generators on them. Both the first-cost and the maintenance would be greater for other equipment with generators.

Saying that the amount of electricity is small may be missing the point. Right now each sports machine is a positive load. Even if each machine were to break even in terms of energy consumption (net consumption = zero), it would be a net gain; because it would take some load off the grid.

Well, the energy generated affects the cost-benefi analysis...

 

[russ_watters]

Are you sure about those figures, Janus? I know of some people who hooked generators to stationary bikes so their kids would have to excercise in order to watch TV. I seem to recall that they got about twice as much watching time as they spent pedalling, which would indicate an output of around 200 watts. Those were fairly sedentary little yard apes, so I would expect that fit adults pushing themselves should be able to do a lot better.

Depends on how big the TV is.

I'm in reasonably good shape (though not very big) and I don't ever generate more than 150W, if the bike is to be believed.

 

[russ_watters]

I'd have to agree with Janus. From what I've seen, the average person isn't going to generate more than 100 watts, but for the sake of arguement, let's make it 200 watts. That's 1/4 hp, quite a bit to maintain for any significant amount of time for the average person.

Now let's say the bike has a 50% utilization rate over a 10 hour day. That's 200 watts for 5 hours, or 1 kw hour. That amount of energy is worth about $.07.

In a year (365 days) that's $25 worth of electricity.

Note also the time the generator is spinning is about 1800 hours. A typical low cost generator isn't going to last more than 2000 or 3000 hours, so you need a much better, industrial grade generator to get the 50,000 hours you'd need to make it worth while. They'll be much more expensive.

For $25 a year, you're looking at something on the order of 20 year payback (about 36,000 hours of operation) without considering interest. There are much better ways of spending that money.

Good analysis. And when you start talking about putting linear induction generators on weight machines, the first-cost goes through the roof. And that doesn't even begin to deal with the difficulty in gathering together all that poor quality power and trying to get it to the grid (brewnog's point).

 

[wxrocks]

You could also approach this from a grid stabilization perspective. There was a PopSci article talking about having plug in hybrids where the car would be an electricity storage device as well to supply short term surges in power demand and would charge suring lower points of demand -- thus allowing generation to run more steady state. Perhaps Gyms could provide the same -- store up power in the winter to be used to cool the gym in the summer... Just an idea.

 

[brewnog]

You're not going to be able to generate enough electricity from gym equipment to power the lights, let alone enough to store it all up and cool the place in the summer!

I'm all for thinking outside the box, but do the numbers yourself. Failing that, trust the people who have already done the numbers.

 

[EnumaElish]

Setting aside the cost issues (and back-of-envelope calculations show me that the juice just isn't worth the squeeze), it'd be a technical nightmare to set up things like treadmills and rowing machines to supplement the conventional power supply in terms of frequency synchronisation. You'd just never get it to work.

This proves you've never been old enough or poor enough. Electric trolleys had a flywheel system attached to brakes; as the car decelerated it changed from load into generator (put juice into the grid). AFAIK the new hybrid cars have a similar flywheel that converts heat into electricity to be stored. But the trolleys did the same thing at the grid level.

 

[brewnog]

This proves you've never been old enough or poor enough. Electric trolleys had a flywheel system attached to brakes; as the car decelerated it changed from load into generator (put juice into the grid). AFAIK the new hybrid cars have a similar flywheel that converts heat into electricity to be stored. But the trolleys did the same thing at the grid level.

Right, and just how much energy do you reckon a treadmill-driven flywheel is going to store? Then, how do you propose you rectify that to 50/60Hz, phase it, and synchronise it with the grid, whilst providing suitable backup for when the customer stops running, and ensuring that the demanded load swings are not imposed on the customer? Oh, whilst ensuring that this is all economically viable of course.

Modern hybrids do not have a flywheel which "converts heat into electricity". They just use a combination of conventional and electric propulsion, and some use some regenerative braking. A ten-tonne tram decending a hill is a far better prospect for such technology than a rowing machine. Do the numbers...

 

[EnumaElish]

Modern hybrids do not have a flywheel which "converts heat into electricity".

If they don't, then they should, just like the old trolleys (except the trolleys were connected the grid).

 

[brewnog]

If they don't, then they should, just like the old trolleys (except the trolleys were connected the grid).

What?

Some use regenerative braking. Read my post again, and then look up regenerative braking. This isn't a "flywheel which turns heat into electricity". Anyway, the benefits of regenerative braking on transport vehicles exist. This thread is about gymnasium equipment.

 

[FredGarvin]

Installment and maintenance are sunk investments -- they are there regardless, and do not matter when deciding the type of equipment being installed. Put differently, they are not asset-specific investments, where the asset is a sports machine of type "L" (Load) or a sports machine of type "G" (Generator). So, installment and maintenance are not part of the cost/benefit analysis for the specific purpose considered here.

This doesn't make much sense to me. Your proposal is to do this, therefore you have to have some kind of business case for doing so. If you do not consider the capital lay out of equipment and technology, how exactly would you characterize the ROI? Every capital investment my company makes has to be accompanied by a business case for doing so. You seem to convieniently leave out the major "con" for doing this kind of set up.

 

[wxrocks]

I under stand where the "current" numbers stand... but it is these type of thoughts or ideas that end up with some benefit to the future. I look at the project I worked on as an Undergrad -- MINOS -- and there may be no obvious benefit to the general public, just scientists figuring out neutrino properties. But just imagine if someone working on it came up with a way to capture more neutrinos (unlimited energy??) -- or even finds a better way to engineer steel or maybe finds a better way to... etc etc -- What I am saying is "trying" a gym like this may not be cost effective now, but may provide insight into better gyms in the future.

 

[brewnog]

It's a nice thought wxrocks, but I don't think humans are going to change enough to provide more than a few hundred Watts whilst exercising.

If we really want to look at improving the efficiency of a gym, let's look at trigeneration systems, more insulative roof insulation, the use of biogas to heat swimming pools, making better use of natural light etc. Or just shutting the bloody things down and showing people that they can exercise outside.

 

[EnumaElish]

1. With the current "climate trends," my guess is more people will likely turn to exercising indoors, rather than the other way around.
2. Even if GEnerator gyms (GE-nerator, GEt it? ) may not clear the hurdle at the existing energy prices, they may do so at higher prices. E.g., once the use of carbon, fossil and/or nuclear fuels are more severely regulated. (And I am not necessarily saying that they should be -- only pointing to an apparent "trend.")
3. Must assume peak pricing; not baseload.
4. May be used as a local (residential) backup; e.g. during a blizzard with a blackout, or on the Space Station or the Lunar Base -- those times when the price of energy is infinite.

 

[AlephZero]

May be used as a local (residential) backup; e.g. during a blizzard with a blackout, or on the Space Station or the Lunar Base -- those times when the price of energy is infinite.

Yeah, I can just picture a stream of people rushing to the gym through a blizzard in the blackout shouting "Save the Planet! Pedal Faster!"

 

[brewnog]

4. May be used as a local (residential) backup; e.g. during a blizzard with a blackout, or on the Space Station or the Lunar Base -- those times when the price of energy is infinite.

I don't think you quite get this.

A person on an exercise bike or a rowing machine can produce about the amount of power a couple of light bulbs need, for maybe an hour or two. Let's say "300-Watt-hours". Do you have any idea how little energy this is, when compared with, say, keeping critical hospital equipment online, or even powering your house?

Humans... can't... produce... very... much... electricity. If your community is in such a state whereby there's no power at all in a blizzard, I think getting the locals down to the gym is going to be pretty low on the list of your priorities.

 

[russ_watters]

Most of them will use more energy driving to the gym than they will produce while there...

 

[Danger]

I concede defeat re: my initial response was that it was a good idea. I was thinking of DC generators loading up storage batteries which could then release inverted AC power to help offset the needs of the establishment.

 

[AlephZero]

Humans... can't... produce... very... much... electricity.

A better solution would be to corral all the trolls in the gym. They have infinite capacity to create energy in the form of friction and/or hot air.

 

[FredGarvin]

A better solution would be to corral all the trolls in the gym. They have infinite capacity to create energy in the form of friction and/or hot air.

We could create more energy by taking all of the weight lifting belts, gloves and other unnecessary crap people buy to work out and just burn it all in a pile in the middle of the gym.

 

[EnumaElish]

I wasn't advocating driving out to the gym during a blizzard; just the stationary bike at home. At the very least it can power up a radio during an emergency. Or power up the bike's electronic displays -- so you can get rid of the cords that are a health hazard (tripping) and put the equipment where you like it to be, not constrained by electrical wiring (placement of wall outlets).

Also, there are locales where a lot of humans gather which also have exercise equipments -- e.g. scientific or military bases -- so there's no need to drive to the gym, even during a blizzard.

Isn't the idea that you need to purchase extra energy to burn up existing energy a little funny?

 

[brewnog]

Isn't the idea that you need to purchase extra energy to burn up existing energy a little funny?

No, because as I keep saying, you don't need to do this at all. Go for a walk or a run!

 

[EnumaElish]

We could create more energy by taking all of the weight lifting belts, gloves and other unnecessary crap people buy to work out and just burn it all in a pile in the middle of the gym.

That's at best a one-time solution. The trick is to invent a way to use humans as batteries to power up the E.T.'s HQ. Just like in the film trilogy "Matrix."

 

[EnumaElish]

A better solution would be to corral all the trolls in the gym. They have infinite capacity to create energy in the form of friction and/or hot air.

Are you referring to them hotheads?