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Thread: potential battery

  1. #1 potential battery 
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    ok so i know im not the first person to think of this. im sure the romans even used a similar idea.

    lead is 11.35g/cm^3 or 1135Kg/m^3
    3.14x(5x5)x11=865m^3 (volume of a cylinder 11 meters tall and 10 meters in diameter)(pie times r^2 times h)
    (1135Kg/m^3)x(865m^3)=1,000,000Kg (approximately)
    (1,000,000Kg)x(100m)x(10m/s)=1,000,000,000joules(or watts)=1,000,000Kw=1,000Mw

    lifting a 1,000,000Kg lead weight 100 meters in the air can store and discharge 1000 megawatts of energy per cycle(2 days. one to charge and one to discharge) this would be a lead weight approximately 11 meters thick and 10 meters in diameter (cylinder shape). this could store the amount of energy needed for 50,000 homes. i calculated the energy in meters/second because energy is neither gained nor lost and using newtons comes up with the same relative answer. the weight would take an average of a day to discharge and would be able to charge using one day of renewable energy. each day the renewable energy source would charge one of 2 weights which it would switch between every day. this poses several advantages. the cost is cheaper than traditional batteries. the electricity fed to the power grid is much more stable and doesnt cause generators to kick on and off. this is a major problem with pv solar panels because they loose 90% of their energy output the moment the sun goes behind a cloud. this causes a fossil fuel generator to kick into high gear somewhere just to kick back down the moment the sun comes back out. this causes severe wear and tear on the generator and it uses fossil fuels. last reason is if we have a completely renewable energy source we have to be able to store it because renewable energy doesnt agree with our time schedules. nature does what it wants. so one day we are going to have to have some kind of battery system and this could be cheaper because it doesnt rely on complex chemical reactions. it relys on dead weight and an electric generator. batteries cost a lot because they take accute precision to make meaning lots of man hours and high machine costs. dead weight can be acheived by anchoring to a small bolder. and electric motors and generators are plentiful and cost effective. the average cost of a battery is $1.00 per watthour. a battery system that would hold 1,000 megawatts of energy would cost one billion dollars. i think this battery system could be built for 1/20 of that, 50 million dollars. i assume that by calculating it would take 10 million dollars in materials and 4 times that in labor to build it. anyone have any thoughts?


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  3. #2  
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    You're so right about the sporadic energy of trendy green sources like wind or solar.

    Actually we already pump water uphill into reservoir, as a battery. Later we may drop it down a chute with turbine at the base. The "problem" with that scheme is that many places where terrain makes it affordable, climate makes it more affordable to simply run turbines off the watershed.

    At first I thought you were describing my pet tidal generator. It uses buoyancy/weight of existing floating docks against the fixed pilings. Because it's powered by tides not waves the generation is perpetual. It's also petty power only useful at the isolated dock, whereas your scheme sounds ambitious.

    Can't you find a way to build this cheaper? A lead weight is really too precious. Why not use rock or water? Even concrete.

    Similar to deadweight, is the flywheel. Obviously yours beats all in terms of standby loss.


    A pong by any other name is still a pong. -williampinn
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  4. #3  
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    yes thats the same line im thinking along. i only used lead because it was a heavy demonstration item. other items would be much more cost effective. like sand. fill a bucket with dirt. whatever the material though it has to be somewhat dense so it doesnt take up too much room. if it takes up too much room than your overall structure has to be bigger too. ive heard about the water thing before. i think this is a better idea because the energy efficiency is higher than anything else. for example, electric generators can generate 95% of the energy into electrical energy. electric motors can turn 95% of the electrical energy into turning movement. with water however, the efficiency for the pumps is around 85% and the efficiency on the turbines generating the electricity is around 70%. so the overall loss for the water system is almost half compared to 85-90% for the dead weight. but, the water way is much cheaper to build. im concerned with efficiency because solar efficiencies right now only absorb 20% of the suns potential energy. if we only get half of that after storing it than we are only using 10% of that energy. so this means you would have to build twice as many solar fields to get the same amount of energy. that would double your cost on top of the storage unit costing you more than normal. i say more than normal because solar fields dont currently use batteries. they feed straight to the power grid. but like i mentioned before. without batteries complete renewable energy is impossible. your water idea may prove more cost effective than my idea even after energy losses. a simple idea might be to store our cities water higher than we do now and generate energy off of that. and use renewables to pump it up there.
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  5. #4  
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    a flywheel is also another idea ive been toying with. only problem i see there is flywheels are spinning. and anything moving slowly stops due to friction from bearings and the sort. so a flywheel would slowly be burning away our energy. i figure a dead weight can sit somewhere indefinately without loosing energy.

    ty for the reply. youve given me more to think on. did you know that a 500 megawatt power plant spends 100 million dollars a year on coal. this is enough money to buy the equivalent in solar panels after 20 years. just in the price of fuel. also did you know that you could pay$10,000 less over the life of a car if it was electric instead of gas. electricity is equivalent to $0.60 a gallon. much cheaper and american made. no more foreign oil. so if you saved $10,000. that would be enough to buy more solar panels than you would need to charge that same car. and electrical cars get about 70% energy efficiency compared to gasolines 30%. so you actually put less co2 in the air than gas even though coal is 100% carbon and gas is only 40% carbon. and lastly. our power grid can already support electrical cars because we can charge at night when the usage is low. sorry for straying off subject. we had a good debate in my renewable energy class.
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  6. #5  
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    Flywheels. Yes, bearings are a problem, especially if you want a monumental flywheel. How about a horizontal flywheel floating in shallow water? You could build a fantastic diameter if concrete shell filled with (also spinning) water. At that scale I think the frictional losses of water would be negligible, especially considering nearby water will tend to spin as well.

    I think you can imagine many secondary uses for such a flywheel.


    It's nice to read posts on renewable energy that offer more perspective than agenda.
    A pong by any other name is still a pong. -williampinn
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  7. #6  
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    if i did use a flywheel id probably use a magnetic bearing so there was less friction. but than your limiting yourself on how much torque you can apply to it or take from it.
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