Alternative energy, from alternative forces

[MountainDon]

The system works, within certain parameters. About 75% of the pumped energy can be recovered. So it depends how much the energy to pump costs. It might be a practical use for excess PV or wind power "electrical" storage.


There are large scale commercial systems around the world. One of the first is in Wales, built in the 1980's.

http://engineer.openguides.org/?Dinorwig_Power_Station

http://www.fhc.co.uk/dinorwig.htm



Another concept is to pump air with the excess power; pump air into underground caverns, old emptied oil fields and the like. The compressed air is then used in turbines to generate electricity as needed.

[devildog]

THanks MD, if this doesnt work Im going to bed!

[glenn kangiser]

As Don mentioned, it could not work for full time due to efficiency losses, but as a fill in power gap measure it could work.

The rain water could fill some of the losses but you also want to use te power, which is another loss.

It takes more power to pump the water than the generator can recover.  

The only real way to gain with the hydro is if you have an uphill source of water.

I have that situation at my place.  Water at the bottom of the hill - me at the top.

[glenn kangiser]

If that creek is flowing at the bottom full time then a water ram could be used to pump to the top within limits.  It would work free 24/7 then you may be able to generate a limited amount of energy with the free pumped water.

[NM_Shooter]

To sum up the first and second laws of thermodynamics:

"There is no free lunch; ... heck, there isn't even a reasonably priced lunch!"

Amen!

Anytime you convert from one energy source to another, you have losses in the form of heat (sometimes light, but mostly heat).  Even driving a car up onto a ramp that cycles an assembly to generate electricity... uses more energy from the gas to move the car than you get from the little generator that you might have built.

Alternators from cars are not easy to spin at 2000 RPM with any sort of load attached.  The more power you try to pull from them the harder they are to spin. 

I'm trying to remember the numbers and am too lazy to google.  But 1 HP is roughly 700W.  So 2400 Watts is roughly 3.5 HP, which is about what a gas powered lawn mower generates.  Think about how hard it would be to manually swing that mower blade and cut the lawn as well as that mower does. 

As a side thought, think about how efficient our bodies really are!  With just a small amount of food, we can do amazing things.

Anyway, keep thinking about it Jens.  We need people who are not afraid to push the corners when it comes to innovative thoughts. 

[glenn kangiser]

There goes the ramp theory.

One I have read over the years and have not actually seen done uses a uniflow steam engine powered by propane that is heated with solar - maybe a water bath.  The propane is converted to a gas, runs the engine turning a generator then is condensed and returned to the tank for reuse via a pressure pump or 3 way valve from low to high pressure.  It is a bit complicated so I haven't bothered.  Solar panels are a more passive activity for a lazy man.

[MountainDon]

1 HP = 746 watts

and from a google this AM I found 2 sources that state a human can sustain an effort of about .1 HP.

746 watts x .1 = 74.6 watts  That's a good match for the 75 watts I found referenced yesterday.


Re: food and human power. Think of how much food we'd need to eat if we could put out 1 HP, let alone 3.5   

[glenn kangiser]

If in the next life, I must come back as a light bulb, let me come back as a compact florescent.  [idea]

A 75 watt incandescent is not very bright. 

[John_C]

1 HP = 746 watts
.......Think of how much food we'd need to eat if we could put out 1 HP......

There are a few 1 hp humans around

Fabian Cancellara is the Swiss Olympic time trial and two time World time trial champion.  He is considered to have one of the most powerful "engines" in cycling.  An excerpt from a discussion of his winnining attack in last years Milan - San Remo race.. keep in mind this was at the very end of a 300km ~ 180 mile race

" For example, Fabian Cancellara - "Spartacas" - generated 700-800 watts for 2 minutes in his final attack during Milan-San Remo."

He's been known to put forth efforts of 500 - 550 watts for 20 minutes or so.

[glenn kangiser]

Hmm hmm Gas powered?

[John_C]

Probably.  Many cyclists seem to like burritos.

[glenn kangiser]

I will not be in second place.

[Okie_Bob]

Now that is true wind power!

[phalynx]

well, there you go,  hook a gas line to the bicycle seat after a few burritos,,, you can power a generator to power your house!!!!!  you jsut have to keep eating burritos...

[glenn kangiser]

Will this really work...it's not a perpetual motion machine? hmm

Something smells rotten in Denmark.

[Jens]

I still just don't understand how you can say that a person produces x-watts.  If it is V x A = W, there may be amps, depending upon how measured, but I don't see how there are volts.  Thats an electric personality, that is. 

Didn't know about the resistance increasing as the rpms increases on an alternator, but it makes sense. 

I wonder if there are any liquids that boil at lower temps than water.  I read about a guy that ran PEX through the base of his compost pile, and then to his house.  Compost piles create consistantly high heat, those poor little microbes, slaving away.  I can't remember if he just used it for heat, or as a water heater.  Anyway, I wonder if it would be possible to vaporize the liquid, condense at a higher plane (turning a steam turbine along the way, then drop back down to turn an impeller. 

A friend of mine has had an idea to heat a house with sterling engines in the walls.  The differential output created, would theoretically heat the house in winter, and cool it in summer.

[John_C]

The watt is named after James Watt for his contributions to the development of the steam engine
.....equal to one joule of energy per second.

A Watt is just one measure of work.  So is a horsepower.  1 horsepower = 33,000 ft lbs of work in one minute. with or without a horse involved.  It's also equal to 746 watts .  The watt is the accepted scientific unit. There are watts without volts just as there are horsepower and no horses. Because we rate electrical goodies in watts we think of it as an electrical term more so than a general scientific term.   Maybe if we thought of the 200 hp car as the  149,200 watt car we'd all get used to it.  Actually we may come to that many years from now if the electric car become the norm.

Would it help if we said the average human could generate 1/10 of 1horsepower while riding a bike, and that what we now call a 75 watt incandescent light bulb is really a 1/10 hp light bulb.

When considering alternative energy sources it's prudent to start with how much energy is available.  Hydro is a good example.  Just because I have a stream on my property doesn't mean I can build a useful cost-effective hydo rig.  I need flow and head in some useful combination in order to produce enough power for it all to be worthwhile.  If I know the flow & head there are tables that will tell me how much power (watts) I have available.  I could use those watts to generate electricity, or I could grind grain with them.

[glenn kangiser]

Solar in good sunlight produces about 1500 watts per square yard if you could harvest it all.  Innefficiencies  in equipment prevent getting it all but it's there.  That is about 2 horsepower per square yard.  Going off the top of my head.

Correct me if I'm wrong, John -- good explanation. 

[MountainDon]

Good John.   Below is what I was going to contribute...

I still just don't understand how you can say that a person produces x-watts.  If it is V x A = W, there may be amps, depending upon how measured, but I don't see how there are volts. 

We're using the terms watts as an expression of how much work a human can do, not necessarily as an electrical measurement. It's a convenient measure as we have all sorts of electrically operated devices around us. We could also use horsepower as mentioned, or BTU's, joules, calories and so on.

By stating a human may be able to produce 75 watts we are not saying the human is going to produce electricity directly, We're saying the human is capable of producing that much work.

When talking about electricity the V x A = W equation is true. At 12 volts you would need 6.25 amps to get that 75 watts; but at 120 volts you would only need 0.625 amps for the 75 watts.



There are many liquids that boil at lower temperatures than water. Alcohol, acetone, benzene, gasoline, ether and more. That's not going to help make a turbine to produce work (power) though. Simply put, if the liquid boils with less heat input it contains less energy.

[glenn kangiser]

Propane and many other gasses boil at a much lower temperature than water, but when they change to a gas from a liquid they produce freezing temperatures.  That is how we get refrigeration.  In a closed system they can be recovered and reused as in a refrigerator.  

There are methods that use that for power such as the uniflow steam engine.  Solar can be used as the heat source from which the power is taken.

[phalynx]

I personally wanted to try and create a very small scale coal power plant.  There doesn't seem to be anyone doing it.  So, it must not be worth it.  I figured you could shovel a bucket of coal every 8 hours or so, that ought to produce enough steam to power a generator of some size.

Then again, if we hooked up tubes to all the breathalizers, we could inject high amounts of flammable gas directly into micro steam generators...   new-drunk-hyrbid-police-vehicles.

[John_C]

How much energy do you figure is in a bucket of coal?

Are you talking about a bucket like on a front end loader?

[phalynx]

small bucket... not big bucket.  I don't know how much is in coal.  I do know that I grew up running 1 1/2" scale live steam locomotives.  We could build up a lot of steam with a couple of hand fulls of coal.

[NM_Shooter]

Coal has an amazingly high energy density.  Betcha Don will have a comparison table before this thread is done

I was told once that the average human puts out about 200BTU of heat energy during normal activities.... Just your 98.6deg radiation X surface area of body. 

[John_C]

There are lots of conversion tables.  Here is one

http://hypertextbook.com/facts/2006/LunChen.shtml