alt.energy.renewable

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"Alex" wrote in message
news: @ ...
> On 29 Sep, 00:51, nada wrote:
>> >From "Nuclear Australia"
>>
>> Critics of nuclear energy sometimes point to Germany's planned nuclear
>> phase-out policy as an example of the industry's limited future. Let
>> us put aside the very credible discussions regarding the possibility
>> of that policy being reversed for a moment and turn the tables.
>>
>> How are German renewables performing?
>>
>> As reported in the Herald Sun, Terry McCrann digs into the performance
>> record of one of the largest wind powered systems in Europe.
>>
>> Germany's Netz operates the grid which has one of the biggest
>> 'feed-in' wind power sources in Europe. Each year it produces a
>> WindReport. The latest makes interesting, sober, reading.
>>
>> Germany has 18,300MW (megawatts) of installed wind capacity --
>> close to half Australia's total installed electricity generation
>> capacity, about double Victoria's.
>>
>> Netz draws on 7600MW of that.
>>
>> In the precise German way, it tells us that maximum feed-in was
>> 6234MW at 9am on 15/12/05.
>>
>> Sound great? Except when you read the minimum feed in, at
>> on 27/05/05. Just 8MW. And no, I'm not missing a nought or two.
>>
>> Some 7600MW of installed capacity delivered just 8MW. When the
>> wind don't blow, the electricity don't flow.
>>
>> On average across the year, the 7600 MW of installed wind capacity
>> produced 1327MW. That's an operational level of 18 per cent of
>> capacity. In rational terms, it's insanity.
>>
>> Indeed as Netz notes, installed wind capacity went up 12 per
>> cent in the year but actual wind power fed in to the grid went up just
>> per cent. Because of lower "wind availability".
>>
>> The way you 'solve' this is that 'traditional' power stations with
>> capacities equal to 90 per cent of the installed wind power capacity
>> must be permanently on line to guarantee power supply.
>>
>> So not only do you have to install six to seven times as much wind
>> capacity as the output you will actually get, but you also have to
>> build 'shadow' coal/gas/nuclear(?) as well.
>>
>> That's one power station for the cost of 12 or so.
>>
>> Did I say insanity? Unless you can build big enough batteries to
>> store the power generated when the wind does blow.
>>
>> Funny I should say that. has actually pioneered exactly such
>> a battery. It's the size of four shipping containers, uses
>> 'undisclosed' chemicals and can produce all of 1MW for four hours.
>>
>> See this link for projected vs. actual performance for any day (just
>> select via the calendar on the right side of the page). Interested
>> that they seem to always exceed the projection, but fall WELL short of
>> the 7,600 MWe capacity. The 18% number looks about right from my
>> perusal.
>>
>> As much as I hate to be baited into nuclear vs. renewable discussions,
>> the data bears careful digestion. Just as I've said from the
>> beginning, when you objectify and quantify the discussion and base it
>> on demonstrated performance - the picture becomes MUCH more clear.
>> I've learned something though. In my previous back-of-the-envelope
>> calculations, I was crediting wind with a 30% capacity factor. Seeing
>> the 18% above, I guess I should pull that number back a bit.
>
> This is not an issue until wind is over 10% of generating capacity,
> and probably more like 20% given a wide area of offshore wind.
> Offshore wind should be aiming for 40% capacity factor. They don't
> often suffer from too little wind and if they have too much, nearby
> farms on the edge of the storm should be generating just right.
>
> By the time we have >20% wind, two disruptive technologies could help
> out:
> - Plug in electric vehicles: Charge up cars when the wind blows. By
> 2020, there should be millions of cars that don't mind when they're
> charged up.
> - Domestic gas generator / boilers such as the whispergen. These will
> receive a request to generate electricity. In summer, the heat would
> be wasted, so its quite expensive. In winter, the heat is used. A few
> million boilers with 2KWe capacity adds up to 10GW standby
> generation.
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Plug in electric cars add an additional load to the grid system. They depend
on reliable "off-peak" energy which wind may or may not supply. At such
off-peak times, wind energy takes the same role as it does during other
times- saving energy as coal in piles, etc. What such off-peak loads can
do is benefit nuclear and large thermal plant through steadier loads.
As for the whispergen- again- is the energy available when it is needed.
Certainly it would be used for heating in winter in many areas -leaving
little or nothing to supply to the grid -and when, in most of those areas,
the grid load is high.

You are right in that there are changes in usage and some better ways to do
things (Is whispergen one- I don't know) but when planning tomorrows plant
we have to use what is available today so changes in generation mixes are
slow.

--

Don Kelly dhky@
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