Naked Science Forum
Non Life Sciences => Technology => Topic started by: paul.fr on 03/11/2007 21:16:15
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My goal is to one day own and live in a windmill, how efficient would the sails be at generating electricity? or would it just be better (or possible) to fit a modern turbine to the windmill?
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Windmill for you - water mill for me [;D]... and run the whole house on self-generated electricity [;D] [;D]
Perhaps someone can answer and consider both of them. I'm certainly interested too
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Windmill for you - water mill for me [;D]... and run the whole house on self-generated electricity [;D] [;D]
Perhaps someone can answer and consider both of them. I'm certainly interested too
Hydroelectric power is nothing new, but it is a very finite resource - there is only just so much flowing water available to generate energy for human use. All very nice to think about it as a free supply of energy for you - but it is not so free when someone builds a watermill upstream from you, and thus consuming most of your power. It takes a lot of land to collect the water, and allow it to fall over sufficient distance to have any meaningful amounts of energy, and if you don't own all of that land, then are you not steeling someone else's energy?
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My goal is to one day own and live in a windmill, how efficient would the sails be at generating electricity? or would it just be better (or possible) to fit a modern turbine to the windmill?
I don't know exactly what the relative quantitative efficiency of traditional windmills and modern wind turbines are, but the following are qualitative differences I can imagine.
Firstly, clearly, modern aerofoil design on wind turbines should be more efficient that old fashioned wind mills. Part of this may be offset by having a greater area of sail on a windmill than the wing area of a modern wind turbine.
Secondly, the windmills are designed to turn very much slower than the new wind turbines. This may have some advantage is reduced parasitic drag, but also creates less lift (again, offset by using greater sail area); but more specifically, the slow speed may be useful for directly turning millstones, but is too slow to directly drive electric generators. Even modern windmills often need to be geared up to drive electric alternators, but the gearing on old fashioned windmills would have to be even greater.
This brings us to another area, the efficiency of the internal mechanisms, as frictional losses through gearing and bearings. Modern wind turbines are designed with better materials and better mechanical design. These could be offset by leaving the external aspects of a windmill, but replacing the internal mechanics so that they would function more efficiently.
Now for the real problems.
Modern wind turbines operate higher off the ground than old fashioned windmills. The higher you are off the ground, the faster (and cleaner - i.e. less turbulent) the air stream you are in, and so the more energy you can extract from the air stream.
Modern wind turbines are much lighter than old fashioned windmills (I am referring here to the weight of the moving parts, not the weight of the base). This means that modern wind turbines can more rapidly be adjusted for changes in wind direction and wind speed than could old fashioned wind turbines, and so could be operating in more optimal conditions for a higher percentage of the time in which the operate.
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I bought a wind generator for my boat. It cost about £350 and was lousy value in terms of £ per kWh. But it is convenient and I can convince myself it is 'free energy'. It means my battery is never flat when I want to start my engine.
Great in a rare situation but, for generating my home electricity supply - 'marginal' is the kind word for it.
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You can generate electricity by diesel generator set, it can be used as a standby, emergency unit when there is power outage.
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Under the ice ?
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My goal is to one day own and live in a windmill, how efficient would the sails be at generating electricity? or would it just be better (or possible) to fit a modern turbine to the windmill?
Under 5kw if you are using an economy lifestyle probably no worry.to use the aka silly sails, but would need a low RPM generator type and possibly a gear to change speed ratio to faster.
The worry with wind turbines is the "rotation speed input RPM" and the "security wind speed".as maximum and method of securing the turbine in heavy weather.
personally i would build three different circuits as off grid sets into a house.
lights and small appliances , bedside clocks, mobile phone charger that operate under 1kw e.g. solar 500w wind 500w
Entertainment equipment, small kitchen appliances, small electric motors e.g. refrigerator 1kw,(1kw wind turbine and 1kw solar)
2kw wind and 2kw solar with bulk set of either AGM or sealed lead-acid batteries for hot water, air cond. washing machine (incidentally req. an 8Kw inverter to operate a washing machine and better to use a heavy industrial 10kw transformer type inverter not semi-conductor type for heavy duty - transformer type are only 90 percent efficient throughput but worth the point on heavy equipment)
http://windsolarhybridaustralia.x10.mx/batterycalculatorAH.html
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After the next virus pandemic when all the nations of the world realise how foolish they have been to squander so much energy on wars and peace breaks out there should be plenty of completely sealed nuclear plants designed for submarines on the war surplus market.
One of these should be ideal for domestic use .
Where I live there is a small river the loose that once fed at least 20 mini hydro plants, when I was a boy a few where still where functional but they are now all gone with their ponds all overgrown
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NB. You may not know but a genuine windmill building of the later middle ages "swivels on a turntable" so immense in maintenance cost all round.
Of electricity consumption a standard modern house can reach 15kw current draw during some phases of operation which is why the inverter on the telegraph pole for the individual supply to each house is rated 30kw as installed by the supply company.
Also a deep cycle battery of 100ah rating can only quite discharge 500w per battery continuous for a supply scenario - 200 to 300 watt P/battery is a safer level.
e.g. chains of 40ah deep cycle can only quite safely discharge a maximum 200watts per battery continuous.
One more thing, the quantity of discharge of a battery bank for the days basic average requirement should only be 10 percent akin to 10 percent DOD for lead acid batteries and should be a 15 to 20 year rated standby chemistry.
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. You may not know but a genuine windmill building of the later middle ages "swivels on a turntable"
Must play havoc with the plumbing.
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After the next virus pandemic when all the nations of the world realise how foolish they have been to squander so much energy on wars and peace breaks out
Just like 1919.
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. You may not know but a genuine windmill building of the later middle ages "swivels on a turntable"
Must play havoc with the plumbing.
Plumbing was a disgusting Roman import, driven out by the Saxons and replaced by much healthier buckets of stagnant water and slops emptied into the street. Life expectancy may have plummeted in the midden ages, but nobody got their toes stuck in a bath tap.
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My goal is to one day own and live in a windmill, how efficient would the sails be at generating electricity? or would it just be better (or possible) to fit a modern turbine to the windmill?
As others have suggested, you would need a set of batteries. The batteries are probably the most expensive part of the setup. you would also need to monitor the weather on apps like climacell or weatherbit to forecast the environmental factors. Even though the initial cost is high, you could save a lot of money in the long run.