Update (5/2/07): It has been brought to my attention that my assesment that the German compnay inflated their figures is likely false. It is likely that they used average German home consumption figures, which are drastically lower than those in the United States (~3,000 KWh/year/home in Germany vs 8-11,000 KWh/year/home in the US). Taking into consideration this large discrepancy it is likely that my claims that they falsified data are incorrect. I will however maintain that these numbers are not representative of the capabilities of this unit on a global average, as clearly the numbers are skewed for German consumption alone. I will maintain my post and my deduction, including my assertions, here for posterity, but will retract my statement that this company has falsified data.
It appears there is a discrepancy between the figures in my last 2 posts (below). They state that the biggest wind generator produces 4 MW of power, or enough for about 4k homes, and the biggest solar farm is supposed to produce 40 MW of power, or enough for about 6k homes.
6 MW = 4k homes
40 MW = 6k homes
?
From howstuffworks.com on wind energy I gathered the following:
- Watt (W) - electricity-generating capacity
- Kilowatt-hour (kWh) - one kilowatt (kW, 1,000 watts) of electricity generated or consumed in one hour
- A small, 10-kW-capacity turbine can generate up to 16,000 kWh per year
- 10/16=0.625 which is a much higher rate than the larger wind turbines below (average ~0.35 (capacity over hours))
- this does not mean the numbers are false, as there may be large differnces in energy loss with larger turbines, I don't know
- a typical
- A bit of an over-estimation, but nice and round, and close
- typical US home consumes about 1KW/hr, 24*365=8760 KWh/yr
- A typical large wind turbine can generate up to 1.8 MW of electricity
- Or 5.2 million KWh annually, under ideal conditions
- That’s enough to power nearly 600 households.
- 5.2e6/8760=~594, therefore the above holds true, the only set of figures that correlate strongly from multiple sources, thus this is what I am most tempted to believe
- 1.8/5.2=~0.35, as mentioned above
- 1 megawatt (MW, 1 million watts) of wind power can produce from 2.4 million to 3 million kilowatt-hours of electricity in one year.
- 2.4e6/8760=274 homes, 1/2.4=0.4267
- or 3.0e6/8760=343 homes, 1/3=0.333
- => 6 MW = between 1644-2055 homes, indicating that the figures for the worlds largest wind turbine are inflated by a factor of 2, regardless of which numbers you use
- using the 0.35 ratio results in 1.0 MW yielding 2.9M KWh (of wind power), or about 331 homes/MW capacity
- I found that the MW capacity figures are for peak performance (ie sunny days for solar or windy days for wind)
- The capacity factor is the average production over the max capacity
- for coal it may be 75%
- for wind it is probably around 30%
- for solar it is 10-25%
- Taking this into account allows for a solar farm to supply less number of homes than an equivalent capacity wind farm, by as much as 20%
- using the 331 homes/MW capacity rule for wind gives us: a 40 MW capacity wind farm = 13240 homes
- subtracting the 2648 homes (20%) from the above yields 10592 homes, still larger than they stated
- I did find a couple of places on the net talking about the same Ontario wind farm and claiming between 10k and 15k homes could be supplied by it, although most article gave the 6k homes response probably released by the company
- It came down to this: the peak capacity (MW) x the capacity factor = average output x 8760 hrs/yr = average MWh output per year
- This is conveniently divided by 8760 KWh per year that the average us home consumes to get # of homes per year the source can supply
- Ultimately: max cap x cap fac = # homes / 1000
- Applying this to the 1.8 MW for a typical large wind turbine (above) with the 33% wind factor yields 594 homes, spot on with that found before (check)
- Applying this to the 40 MW for the solar farm with the 20% solar factor yields 8 k homes!
- RESULTS
- The 20% solar capacity factor is just a good guess-timator. It is largely dependant on location and thus, the Ontario solar farm must have used a smaller capacity factor for their figures; that is fine, maybe it isn’t all that sunny in that part of Ontario.
- Applying the above formula to the 6 MW for the wind turbine with the 33% wind factor yields 1.98 k homes, about 2k, even with the maximum average wind capacity factor I found of 40% it still proves that the German company building the worlds largest wind turbine have inflated their figures, they used a wind capacity factor of 67% - near the capacity of coal! Clearly not a realistic number for a world average.
- Problem solved!
- References:
1 comments:
Excellent Work!
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