Smart Loads for Solar, Wind, and Micro-Hydro

Discussion in 'Member Casual Chat' started by HereWeGoAgain, Jun 23, 2017.

  1. Derideo_Te

    Derideo_Te Well-Known Member

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    I don't like CF's at all so I was using LED's from the moment they became available. They rock as far as energy use goes.
     
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  2. HereWeGoAgain

    HereWeGoAgain Banned

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    Regarding the quantities of hot water involved for energy storage.

    Recall that the typical home in Ca requires 27 kWHrs of energy a day. And a typical battery has a capacity of 360 Watt-Hrs. So if we try to provide storage for 1/2 of the total energy demand, loosely speaking, we need 14 kWHrs of storage. That works out to require 39 batteries at 23 pounds each, or about 900 pounds, or $2300 worth of batteries that have a limited life.

    If we tried to store this much energy as water heated from the initial 60 degrees or so, to 180 degrees F for heat, it would require about 490 pounds of water, or about 60 gallons, which is no bigger than a typical water heater.

    In practice, this would all have to be over sized by about 50% to compensate for losses and practical limits. So that means more like $3400 in batteries. But as water heaters go, 90 gallons still isn't out of the ordinary. It would have to be specially designed but it isn't size or weight prohibitive. And the the heating coil in a standard electric central air system could easily be replaced with a water-to-air heat exchanger.

    Better yet, go to passive radiator heat so no fans are needed, just a relatively low-power water pump.
     
    Last edited: Nov 5, 2017
  3. HereWeGoAgain

    HereWeGoAgain Banned

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    As for the cooling capacity of your pool - for a free pool heater and reduced air conditioning bill:

    A standard central air system might have a rating of 25,000 BTU [per hour]. And by chance a typical pool has perhaps 25,000 gallons of water. At 8.3 pounds per gallon we have about 200,000 pounds of water. 1 BTU can raise 1 pound of water, 1 degree F, and running the air conditioner for 10 hours means 250,000 BTUs. So we expect the pool temp to increase by about 1.2 or 1.3 degrees F a day [ignoring ambient factors].

    In the mean time, while the pool is warming up by 1 degree a day or so, this process simulates a geothermal heat pump, which is discussed below and a mirror image of the air conditioner. The same rules apply.

    https://en.wikipedia.org/wiki/Geothermal_heat_pump

    As long as the pool water is cooler than the outside air temperature during the day, this process reduces the cost of cooling the home. Realistically, it could reduce the AC power bill by as much as 44%.

    And again, because the pool is heating an equal amount for free, the total benefit is up to about 100% of your air conditioning bill [by doing double-duty].

    All that is required is to interface the pool water with the AC condenser coil, rather than cooling the coil with air and a loud fan. This would be a special device but it could be special ordered, or an existing system modified by a qualified company.
     
    Last edited: Nov 5, 2017
  4. HereWeGoAgain

    HereWeGoAgain Banned

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    Just curious about off the shelf today. With an average demand of 1000 Watts, a 5000 Watt solar panel should suffice in areas that are solar friendly.
    5200 Watt (5kW) DIY Solar Panel Kit w/String Inverter - $8000
    https://www.gogreensolar.com/products/5000w-diy-solar-panel-kit-grid-tie-inverter

    With 27kWHrs per day and typically $0.18 per kWHr, we have $4.86 a day, and about 4.5 years to pay for itself if it can be utilized 100%.
     
  5. saveliberty

    saveliberty Well-Known Member

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    My electric, water and sewer bill is about $150 a month. Those rates do not seem attractive.
     
  6. HereWeGoAgain

    HereWeGoAgain Banned

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    This is the typical rate for a typical home in California; ie. this is what they pay now.

    If your bill is that low then you wouldn't need as much power. Do you have natural gas? Do you have a house or an apartment? Is your home large or small? Do you live in an extreme or moderate climate? What do you pay per kWHr? There are many variables.
     
    Last edited: Nov 5, 2017
  7. saveliberty

    saveliberty Well-Known Member

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    Yes. I have a gas dryer and furnace uses it too. Last time I looked into solar, my area of Michigan did not have enough sunlight to be reliable as a source. Also the breakeven point was past the useful life of the panel. Same for wind power which uses a high steady speed for its energy production figures.
     
  8. HereWeGoAgain

    HereWeGoAgain Banned

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    Well that makes quite a difference. Two of your highest energy demands are met by natural gas.

    The price of solar is dropping like a rock. What is not practical today will be soon. In fact, before long you may be able to paint on a solar panel! Just spray it on, let it dry, hook it up.

    Wind is practical in some areas but Michigan isn't one that comes to mind.
     
    Last edited: Nov 5, 2017
  9. saveliberty

    saveliberty Well-Known Member

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    I am waiting for either power source to become more effective. Government subsidies need to be reduced for all energy types.
     
  10. HereWeGoAgain

    HereWeGoAgain Banned

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    I was stuck in the same boat. Our location was no good for solar. I got very serious about putting in a small hydroelectric generator as we had creek that could provide about 5000 watts of continuous power. But the water was so swift that it moved too much rock. The maintenance costs would have been prohibitive.

    I knew of a another guy near me who had a decent creek, a small river really, with about a 20 foot waterfall. He was making a killing selling power to the power company. IIRC he was making about $10,000 a month. So small hydroelectic [micro-hydro] is definitely viable in the right location.
     
    Last edited: Nov 5, 2017
  11. saveliberty

    saveliberty Well-Known Member

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    Michigan has placed itself in a ad position when it comes to power production. We are taking all nuclear off line, sulfur standards killed coal fired plants and alternative energy plans cannot provide the power needed to replace let alone meet growing demand.
     
  12. HereWeGoAgain

    HereWeGoAgain Banned

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    Why don't they build natural gas powered plants? We have an abundance of NG. And it's a lot friendlier than coal.

    We didn't have the option for NG in our area. We were all electric... or wood. :D I've cut and split more wood than I care to remember.
     
    Last edited: Nov 5, 2017
  13. HereWeGoAgain

    HereWeGoAgain Banned

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    PS. I have spent most of my life developing new systems and processes. So I'm not just shooting from the hip here. This is what I do. But for every 100 things one might like to do, the reality is that one or two can be life consuming. These are some of the ideas I've always wanted to pursue but never was able to do so.

    At one point I did manage to team up with a company that was making green modular homes. It looked like I was going to be able to implement some of my ideas. But they didn't survive the crash of 2008.
     
    Last edited: Nov 5, 2017
  14. HereWeGoAgain

    HereWeGoAgain Banned

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    A minor correction and an additional comment: The text in bold above is true if you have resistive heating [electric coils], which is common. But a heat pump is more efficient because it operates by moving heat, rather than generating heat. So my statement isn't entirely true if you have a heat pump. There is some benefit to using energy-saving lights even when the heat is needed. And if you have gas heat, it depends on the price of gas.

    One more thing about the logic of refrigerators: When it is 30 degrees F outside, why do we pay to keep food cold in a warm house? Whenever the air outside is colder than the air in the home, the fridge should be immersed in the cold air from outside, not the warm air from inside. It wouldn't be difficult to do this with minor design changes to the kitchen. For example, by simply putting the fridge in an insulated closet with vents to the outside air, most of the energy demand for refrigeration could be all but eliminated in many areas for a good part of the year. In some homes you could even cut a hole in the wall and mount the front of the fridge flush with the wall, and build a small enclosure around the rear of fridge on the exterior of the home.

    It is really such an easy fix. The fridge isn't a huge load, but everyone has one or two and they operate 24/7. They appear to constitute 10% or more of the annual electric bill. The large ones could be much more than that.
     
    Last edited: Nov 8, 2017
  15. Just_a_Citizen

    Just_a_Citizen Well-Known Member Past Donor

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    Wasn't there a study or something, showing Salt, as a great energy storage option? Especially where water heat has been discussed here...
     
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  16. HereWeGoAgain

    HereWeGoAgain Banned

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    I haven't heard about such a study but it could be true. But, why add complexity where none is needed? Hot water is more than sufficient as an energy storage medium. I have already shown that. Salt is highly corrosive and starts getting a bit exotic. Part of the key to most real solutions is to keep it simple. In fact, much of the time spent to develop new technologies is a constant process of reducing complexity.
     
    Last edited: Nov 8, 2017
  17. Just_a_Citizen

    Just_a_Citizen Well-Known Member Past Donor

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    I was kinda just wondering out loud. I'm remembering the heating process being similar to Solar collection. The salt is super heated, & provided super heated steam, & in another application, it was used like geothermal heat.
     
    Last edited: Nov 8, 2017
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  18. HereWeGoAgain

    HereWeGoAgain Banned

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    That is for very high temp operations, where you have huge concentrations of solar energy directed at a target. They generate so much heat the the salt is liquefied. Apparently it is more efficient than other options as a heat carrier at those temps.

    [​IMG]
     
    Last edited: Nov 9, 2017
  19. HereWeGoAgain

    HereWeGoAgain Banned

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    It gets a little more interesting. I've copied and modified this example from
    https://www.engineeringtoolbox.com/evaporation-water-surface-d_690.html

    For a swimming pool with water temperature 25oC the saturation humidity ratio is 0.02 kg/kg. With an air temperature of 25oC and 50% relative humidity - the humidity ratio in the air is 0.0098kg/kg - Mollier diagram.

    For a 35 ft x 20 ft [10m x 6m] swimming pool and 0.5 m/s air velocity above the surface - the evaporation can be calculated as

    gs = ( 25 + 19 (0.5 m/s)) ((10 m) (6 m)) ((0.02 kg/kg) - (0.0098kg/kg)) / 3600

    = 0.006 kg/s

    Heat supply required to maintain the temperature of the water can be calculated as

    q = (2257 kJ/kg) (0.006 kg/s)

    = 13.5 kW

    And finally, we have 3413 BTU / Hr = 1 kW

    So we need about 13.5 x 3413 = 46,000 BTU/Hr just to maintain the temp, which is almost twice the value of the 25,000 BTU per hour AC unit originally considered.

    So, once the pool reaches ambient temps of 25 C or so, unless it is kept covered, evaporation will remove more heat than the AC is adding.
     
    Last edited: Nov 10, 2017
  20. HereWeGoAgain

    HereWeGoAgain Banned

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    Wire sizes: If in the example of a typical home in Ca. the total power demand could be averaged as I am discussing, this is how the wire sizes compare - it provides a rather dramatic perspective.

    For the same amount of total energy over a year:
    The minimum wire needed to power the home now for a 200 amp service is the 2/0 AWG, seen on the right. If the load could be averaged, you could use the smallest wire seen on the left - 14 AWG. And technically you could use 16 AWG, which it too small to be shown. That is the advantage in power averaging [intelligent load management and energy storage], in a snapshot.

    [​IMG]
     
    Last edited: Nov 11, 2017
  21. Texan

    Texan Well-Known Member

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    I like the heat exchanger in the bottom of the swimming pool idea. That even saves the cost of running the cooling fan in the AC compressor. My wife wants a pool and I didn't want the hassle, but I may have to rethink this.

    I don't see much benefit of storing heat in the South. We only have a 2 month Winter, if that. If you do store heat, heated floors are a must.

    If you also supply your own water, you can pump water to a raised tank with excess energy. It can provide water pressure or maybe electricity generation (at a loss of course). Used water can go to your garden.

    A good thing to consider is variety of energy sources. It's not always sunny and not always windy, but having both can greatly help your battery limitations.

    A smart home can shut down outlets when not in use to eliminate ghost loads. You can also super cool(or heat) your house at peak energy production times to minimize the need to store energy.

    If you are building, consider super insulating and window and overhang placement. Tree placement as well.

    Anyway, that's my ramblings.
     
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  22. HereWeGoAgain

    HereWeGoAgain Banned

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    It would probably be a little easier to install the heat exchanger in the AC unit, and pump the water to and through it, rather than mounting it in the pool. The water can be run at low pressure whereas the Freon is in a pressurized system. Any AC engineering company should be able to do the installation and size the equipment.

    In a hot State like Texas this could yield significant benefits.
     
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  23. HereWeGoAgain

    HereWeGoAgain Banned

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    Look to companies that do geothermal systems. It is just a slight twist on what they do already.

    Here is a big place in Texas
    http://www.amgeosystems.com/

    It is funny to note that in principle, you are transferring some of your electric bill to your water bill. In part you pay for this in evaporated water. But the trade off is pennies on the dollar.
     
    Last edited: Nov 25, 2017
  24. Guess Who

    Guess Who Well-Known Member

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    I learned everything i know about solar from a preppers site in the Energy Forum ' Preparedsociety.com 'a lot of really good solar info there from hands on preppers.
    I'd have to go look up what we have now forgot or go back to Energy forum there.
    I know we have 2 AWG and for battery bank 4 AWG, if I remember right. One runs the power from battery bank to charge controller, then inverter and meter and wire gets bigger as you leave the bank.
     

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