Windfarms are POINTLESS!

[KrazyHorse]

He's stating that his rule of thumb takes you from max capacity (which in solar panel terms is going to be the maximum output of the given panel basically at noon on the equator) and how that relates to the average daily power. Read it again. And again. And again.

[KrazyHorse]

Originally posted by LordShiva
I'm going to be interviewing potential consultants next month. I think I'll use this question for one of the guesstimate cases

Let's see. I know that my monthly electricity bill is ~60$ for two people. ~8 cents a kWh. Call it 8000 kWh per year for two people. Say that home consumption is 50% of total. 8000 kWh total per person.

8000*300 million = 2.4 trillion kWh. Hey, not bad. Off by ~30%

Solar constant is ~1400 watts per square meter.

Solar cells are generally ~10% efficient. 140 W/m^2. Divide by 4 to get average daily efficiency at reasonable latitude (please take note, Danish people). 35 W/m^2.

(2.3 trillion*1000 / 35) = 80 trillion

80 trillion/8000 = 10 billion

10 billion/1million = 10 000 km^2

= a square 100 km on a side.

[BlackCat]

Originally posted by KrazyHorse
He's stating that his rule of thumb takes you from max capacity (which in solar panel terms is going to be the maximum output of the given panel basically at noon on the equator) and how that relates to the average daily power. Read it again. And again. And again.

That is pure BS. Why don't you try to read it, read it again, and then yet another time. He nowhere says that that rule of thumb is something like "on average a solar panel only delivers a 1/4 of it's power based on an 24 hour average". That would be a very stupid way to measure the effect of a solar panel and besides that, a very vauge way of describing it.

Do you really think that solar panel producers specify the efficiency based upon the production during the night ?

Saying that you only can expect a quarter of the specified effect because there also is something called nigth is simply rediciulous.

[KrazyHorse]

Originally posted by BlackCat


That is pure BS. Why don't you try to read it, read it again, and then yet another time. He nowhere says that that rule of thumb is something like "on average a solar panel only delivers a 1/4 of it's power based on an 24 hour average".

You mean, something like:

the average daily output in a sunny mid-latitude place will be 25% of the max capacity

Maybe it's because you're Danish, but that's exactly what any English person would understand.

[KrazyHorse]

But, you know, I just read physics papers all day long, and they use phraseology exactly like that, so what the **** would I know?

[Zkribbler]

Originally posted by KrazyHorse
You mean, something like:

the average daily output in a sunny mid-latitude place will be 25% of the max capacity

Maybe it's because you're Danish, but that's exactly what any English person would understand.

MMmmMMmMMmmmmmMMmm, Danish.

[BlackCat]

Originally posted by KrazyHorse
But, you know, I just read physics papers all day long, and they use phraseology exactly like that, so what the **** would I know?

No wonder why canucks suck so badly if that is your methodology.

Normally, you are quite brigth, but you seems to miss my point wich is that Oerdins thumb of rule may be flawed. Strangely enough, he has kept a very low profile

[Dinner]

It's because it was dinner time and now I'm going to a friend's birthday party. I had to go to the store to buy a last minute gift as well. See you all in the morning when I will recalculate the numbers with KH's changes.

[BlackCat]

That is of course allowed


Though, it would be nice if you provided documentation of how you reached your 1/4 reduction since it seems to be the main problem between KH and me

[Aeson]

Originally posted by Oerdin
Backpeddle? I repeatedly said it will have niche applications but it will remain a small time player. That's just the economics of practicality.

You said solar is not the answer, and never would be.

I am pointing out that such a position requires there to not already exist the potential for solar to provide a major portion of our energy requirements. It also requires that no new advances in solar power could possibly make it so. (Since it's actually already possible, that is sorta a moot point.) If you wish to continue to assert that solar can never be a major contributer, please provide some evidence to support the assertion.

Here's what I get:

So the panels you linked to are roughly 1m^2, produce 32.5W/h, and cost $699.
32.5W * 8760h = 284700Wh/m^2

http://www.eia.doe.gov/cneaf/electricity/epm/table1_1.html

Total US electric consumption in 2005 was ~4,054,688,000,000,000Wh.

4,054,688,000,000,000Wh / 284,700Wh = 14,241,966,983m^2 / 1,000,000 = 14241km^2

Thus ~120kmx120km would cover it, though that is obviously not allowing for real world conditions as far as spacing, and it would be producing it all during the daytime of course, little to nothing at night. I don't know how much wasted space there would be. Cost at list price would be 14,241,966,983 * $699 = $9,955,134,921,117 or ~$10 trillion without any sort of bulk discount or necessary infrastructure. Very expensive, yes. Not outside the realm of possibility though. For instance, the cost represents the equivalent of ~33 years of petroleum imports at current rates and usage (which both tend upwards). 5,005,541,000 barrels in 2005, or $300,332,460,000 at ~$60 a barrel.

I wouldn't recommend that of course. I don't like solar panels, they are inefficient and rely on toxic chemicals.

The ~14% efficiency from those panels can be doubled. ~30% efficiency is achievable with the Stirling dishes mentioned in this thread already. The article stated that 4,500 acres (/247.1 = 18.2km^2) could produce 500MW (I'm guessing this is an average output given how the numbers work out, but could be wrong about that) with 20,000 dishes on existant powerlines and 850 MW with upgraded lines. (And with more dishes? The article doesn't say.)

500MW * 8760 = 4,380,000MWh
850MW * 8760 = 7,446,000MWh

4,054,688,000MWh / 4,380,000MWh = 925.7 * 18.2km^2 = 16848km^2
4,054,688,000MWh / 7,446,000MWh = 544.5 * 18.2km^2 = 9910km^2

So an operational solar farm using Stirling dishes would take about the same amount of land as the theoretical panel array, and have 18.5 million dishes. The cost for the dishes would be 18,514,000 * $75,000 = $1,388,550,000,000. Now 1.4 trillion, that's quite doable I'd say. The hard part would probably be the actual manufacture of that many dishes, though that investment could help pay itself off by continuing to sell dishes to the rest of the world. Roughly the cost of 4 years of petroleum imports...

Of course we'd only want a portion of that, since we already have some clean energy sources, and since all nighttime use (which I've included in the total draw) would still need other supply (or storage). Energy storage advances would cerrtainly be useful... as mentioned previously, perhaps hydrogen gas? Hydro pumped storage can cover some of it too.

[Tingkai]

Originally posted by Doddler


it's not mangled at all. The coldest spells in winter are generally when we have light winds and high pressure sits over us (& for extra effect, snow cover). Wind farms don't export power during these times of system stress.

The hottest spells in summer are when we have light winds and high pressure sits over us. Wind farms don't export export power during these times of system stress.

You got part of the first bit right, but most of what you say is off the mark.

The mistake is the your contradiction of associating high pressure zones with cold temperatures and hot temperatures.

High pressure zones are created by colder air descending from higher altitudes. Low pressure zones are created by warmer air rising. So the hottest temperatures are often associated with low pressure zones, not high pressure zones.

The idea that there is no wind during extreme cold or hot temperatures is also false.

Weather is dynamic, not static. Hot air at ground level rises, cools then descends creating a constant cycle that is not only up and down but also lateral. The cycle moves cold air from the north to the south during winter.

Wind is affected by a variety of factors including the Coriolis effect, the ground heating during the day and cooling at night, the jet stream, and the difference between surface temperatures of water and land.

John Hiatt has a line saying: "She came onto him like a slow moving cold front." It's a great lyric, but in reality cold fronts move quickly and are associated with wind.

[Solly]

Tingkai - maybe our weather systems are a little different!

[Tingkai]

[DRoseDARs]

By a factor of 4!

[Solly]

Well we are surrounded by 12-17degrees seas, which a moderating effect when the wind blows.