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Forum Index : Windmills : Windmill System
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crazyk Newbie  Joined: 27/01/2009 Location: AustraliaPosts: 12 |
Hi all, You can probably tell that I'm a newbie to this stuff and my understanding of electronics etc is limited but I've gotten really interested in generating power using a Windmill. I've just looked at my latest electricity bill and I consume about 840KWh per 91 days = approx 10KWh / day If I hypothetically wanted to run my entire requirements off Windmill power how would I design my system? What would be the best battery bank setup? What would be the best motor? If I'm asking a really really involved question not fit for this forum please let me know. |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
10kwh per day is A LOT! I run a air conditioner 24/7, have a low efficiency undersized electric hot water system, and use a 1kw jet pump to supply my water, and I use about 2.2kwh per day. To build a system using either wind or solar to supply your 10kw a day would cost 10's of thousands of dollars, maybe even over $100,000! If you wanted to build your own windmills based on the F&P as used in most of our windmills, you would need about 30 of them, in strong winds, or about 100 in light winds. What you need to do is look at your power consumption. Whats soaking up all that power? Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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SparWeb Senior Member  Joined: 17/04/2008 Location: CanadaPosts: 196 |
Since batteries are one of the biggest costs in a RE system, you can start with that, with the information you've provided. Assume you want to supply 10 kWhr for two days, because sometimes the wind doesn't blow when the sun doesn't shine. 20 kWhr can be re-written as 20,000 Watt*hour, or 20,000 Volt*Amp*hour If you use a 48 Volt system, then 20,000 / 48 = 417 Amp*hour If each 12V battery you buy has a 100 Amp hour capacity, then you need: 48V/12V= 4 batteries per row 417Ah/100Ah = 4.2 rows (round up to 5) 4*5=20 batteries. Full to flat, that set of batteries will get you through two days, theoretically. Actually, it's damaging to drain a battery to zero (usually), so setting the limit to 50% discharge means you need: 40 batteries. Accounting for inefficiency in your inverter (85%)... 40 / 0.85 = 48 batteries To last longer than 2 days, you need proportionally more. If each of the batteries costs 100 AUS dollars (I have no idea how much stuff in Oz costs) then that bank of batteries will cost you 5000. Next you're going to look for the price of a windmill / solar array that will keep your batteries charged up, electronics to manage the system, a tower to hold the mill up in the sky, an inverter that can supply your PEAK demand power.... Steven T. Fahey |
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| crazyk Newbie Joined: 27/01/2009 Location: AustraliaPosts: 12 |
Gee is 10KWh really that much? I'm not too sure what we have that would be using all that energy. Has anyone used those plug in the wall energy consumption devices? Are they good / accurate? Sparweb, thanks so much for your explanation, that's exactly what I was looking for that gives me an Idea on how to calculate an approx system cost, excluding the other stuff. Wow that's great guys I'm so happy with the response. Even though this scenario is way too expensive I'll have to do some digging on how you would spec a motor to charge the system. Cheers and thanks |
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| SparWeb Senior Member Joined: 17/04/2008 Location: CanadaPosts: 196 |
I use 10 kWhr per day, too, in the summer. In the winter, that goes up. A lot. My house is heated with natural gas, but the fan is electric, of course. Some rooms need electric base-board heat. The layout of the house turns out to be poor for lighting. CFL's have helped somewhat. Most winter electric consumption is from electric water heat for animal stock troughs, to keep the water from freezing. Not a proplem that most urban people encounter! I used a plug-in electric meter on all of my appliances. Things like the dryer which have special plugs I estimated. When I added everything up, applied appropriate "on" times for each, and made separate columns for the summer and winter use, I eventually came up with a model that matches closely what I use per month, in all seasons. It was enough to roughly size up a system of my own... ... and then I saw the light....  Steven T. Fahey |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Gizmo, No fridge, TV, microwave, computer, washing machine? My fridge is low consumption, 1kWhr/day. I expect your fridge would be similar. A TV, approx 70W for a small unit up to 500W for a decent plasma, 0.3kWhr-2kWhr/4hours. Computer, same sort of consumptions as mid range TV, 0.4-1kWhr/4hours. Some people don't turn the computer off. Washing machine will depend on hot water usage. I still purchase approx 2kWhr per day from the grid. I export a lot more usually. My home with 3persons living, with 2 at home all day uses approx 5kWhr per day, of which 3 comes from solar/wind sources, before surplus is exported, up to 15kWhr on some days. I know of some home air conditioners that can use 100kWhr/day. I had a carrier rotary RAC,1/4hp, now given away, that I had in Darwin, that was the highest energy rating, 5&1/2 stars. This still consumed 180W when operating, approx 4kWhr/day. When I lived in Darwin, families budgeted $5-$10per day for air conditioning, depending on number of rooms. You must have cold room insulation in the walls. I doubt most people could achieve the low power consumption you seem to have. Good work. Gordon. become more energy aware |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
My powerbill says I average 2.2kwh per day, maybe its a false figure, will have a closer look when I get home. Big widescreen CRT tv on about 3 hours per day, I wont have a plasma for the excessive power they use. Place is very well insulated, all windows have curtains, door closed, only cooling the living area with the AC. Medium sized fridge, good star rating. PC on for 5 to 10 hours per day. Washing machine F&P cold cycle. Only use a cloths dryer if its raining and I need the cloths that day. All lights are fluro or CFL. I use home made eco-switches on most outlets, so when I go to bed or leave for work EVERYTHING is turned off except the hot water system during the day and the AC on hot nights. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| crazyk Newbie Joined: 27/01/2009 Location: AustraliaPosts: 12 |
Wow, some great replies guys. Yeah well I run a 420Lt F&P fridge, Ducted heating, and split system Air con's. I'm going to look at what period my consumption is over but clearly I need to do a little more homework on what is consuming what. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
I have a friend who had a second fridge in the workshop to cool 1 bottle of water and his super glue. They also used the cloths dryer instead of the cloths line, was easier 
Their power bill was pretty bad too. They have since sold the 2nd fridge and use the cloths line, made a big difference. The main thing is to only use the power you need. Dont heat or cool rooms that are not in use, turn off the TV if your not watchng it, little things like that will make a BIG difference in the bill. Another trick I do is turn off the AC when I'm cooking dinner. I open the doors and windows to let the breeze through and get rid of that heat from cooking. When I'm ready to eat, I close up and turn the AC back on. A small gain, but still a gain, and you dont stink out the AC filter. I set the temp at 25c, no lower. A pedistal fan helps circulate the air, their cheap to run and make a big difference. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
I suppose my in house fridge does about the same as it seems to run all the time now in high summer. Just for comparison what can be done, I modified an old upright fridge (which I bought second hand in the seventies!) by taking the workings out of its rusting cabinet. I then made a chest fridge box to the same internal volume the original fridge had but with a 9mm plywood case and 75mm foam insulation all round. Inside is 3mm ply lined with 1mm ABS plastic sheeting. The foam was just various styrofoam panels I had salvaged from packaging, layered in & expanding foam used to fill any gaps. The compressor and condenser sits external next to it on a shelf, the evaporator is fitted on the inside of the cool box. Water bottles freeze within the old fashioned evaporator and highest temp. in Summer was about +6 degrees at the farthest corner from it. The thermostat is set to its lowest setting (1), any higher and everything inside the coolbox freezes. No regassing was required as I could bend the copper tubes very carefully to fit the new home of the evaporator. This contraption now keeps my drinks cool in the non A/C shed. I connected it to an energy meter on January 2nd 2009 and this meter had just ticked over to 9KWh total consumption. Based on that it should take well under 100KWh for the full year to run it. The compressor only runs a few minutes at a time and comes on infrequently. It keeps amazing me that a 40+ year old fridge compressor just keeps on running.... The idea is now to power it from wind (and solar) RE once I get all the bits for that ready. Anybody knows which 24V inverter could start & power a fridge? Their specs seem to be cagey on that load. Klaus |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Oops. Now I feel like a idiot. Just had a closer look at my power bill. I have two services, one for the pump and one for the house. I thought they were combined, and the one I grabbed was actually for the pump. Yep, my pump uses 2.2kwh per day. As for the other bill, its kind of scary. On average, OVER 10kwh per day. I wont say how much exactly, I've suffered enough embarrassment for one posting. I know the little electric hot water system is the main culprit, cause I'm very green with all my other electrical use. Time to go solar, or have cold showers. I might investigate further and get back with its actual power consumption. As for my comment above "10kwh per day is A LOT!", I take that back. 10kwh is pretty good actually. 
Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Gizmo, I was wondering how you ran an air conditioner 24/7 on 2kwh/day, and concluded it was a wet towel with an extra bucket of water... figured the small hot water unit to be an electric jug 
The jet pump must have been to fill the jug. 10 kwh /day is pretty darn good with electric hot water... ( my 160ltr hot water can get through 3-6 kwh/ day if the boss decides to have long showers  )
.........oztules edit... you may decide to wind up the air conditioning to sop up some of that extra sweat from your brow as you ponder hacking of your left one and sending it to birdhouse Village idiot...or... just another hack out of his depth |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
This is not strictly windmill related, but, an aspect of tank rain water usage, reticulated into a house supply is the power required by the pump. A few kWhr per day does not make this quite as green. If you had a grid connect solar system, this could equate to up to $300 lost income from exported power per year to pump water. I have gravity fed tank rainwater for drinking. A pressure pump system is not on the cards. If a household consumption can be reduced to 2-3kWhr per person per day, then this is a good goal. I think this is about the limits without going without too much. Subsistence living would be < 1kWhr per day for a household. I think the creature comforts will be hard to give up, fridge, hot water, microwave, TV, etc. Gordon. become more energy aware |
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| crazyk Newbie Joined: 27/01/2009 Location: AustraliaPosts: 12 |
GWatPE, Been thinking about your post and correct me if I missunderstood it. For the hobbiest or Tinkerer my reply is not pertinent, but to the serious Generator it is. Generally people have their houses already wired to the grid and appliances connected to it. Would it not be more economical and cheaper to just set up a system that connects to the grid and delivers you credits from the power supplier and then you just draw from that? No need to worry about peak usage or anything. Hope that makes sense. I'm just looking back at my original question where I asked what system I would need for my circumstance and going by all the replies it would be quite expensive, whereas If I make a system that I can get connected to the Grid, I would just be delivering myself credits and not having to worry about which appliances I want to run of generated power. Obviously I would not be covering my consumption entirely but would be reducing what I draw from the Grid. Just my two bob's worth. |
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AMUN-RA Senior Member Joined: 10/03/2007 Location: AustraliaPosts: 144 |
if you only use 10 kwh a day a then a 2 kw system should give you enough to live on, I use 39 kwh per day with wife and 3 kids thats on top of what my 2kw system produces Mick ps I turn off everything as soon as they walk away so I cant reduce much more withought reducing the family Every day the sun shines & gravity sucks= free energy. |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi crazyk, OFF grid RE has a different set of rules to ON grid. I have a full interactive hybrid system, that takes what I consider the best of both. With grid connect solar, maximum return occurs when all the solar is exported. For most households, this is not possible, unless no power is consumed within the house during the solar part of the day. The real benefits of a grid connect solar system are achieved with the higher buyback rate on exported power, if this is possible. Gordon. become more energy aware |
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| crazyk Newbie Joined: 27/01/2009 Location: AustraliaPosts: 12 |
So let me see if I understand. If I set up a dedicated system and connect it to the grid. My system generates 3kwh per day My consumption is 10kwh per day I will get charged by the power company for 7kwh per day. Is this correct? If so then that saves me having to set up a battery bank and special powerpoints to run off the generated electricity. |
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