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<br />Table 1 Ordinal production run numbers of machines of various capacities
<br />designed to meet various national wind power capacity goals
<br />
<br />Machine
<br />rating
<br />(MW)
<br />0.,3
<br />0.,6
<br />1.2
<br />2.4
<br />
<br />12
<br />
<br />100.1 - 41,0.0.0.
<br />10.0.1 - 21,0.0.0.
<br />100.1 - 11,0.0.0.
<br />50.1 - 5,50.0.
<br />
<br />National windpower goal (GW)
<br />120.
<br />10.,0.0.1 - 410,0.0.0.
<br />10,0.0.1 - 210.,0.0.0.
<br />10,0.0.1 - 110.,0.0.0.
<br />5.0.0.1 - 55,0.0.0.
<br />
<br />120.0.
<br />
<br />10.,0.0.1 - 4,0.10.,0.0.0.
<br />10,0.0.1 - 2,0.10,0.0.0.
<br />10,0.0.1 1,0.10.,0.0.0.
<br />10,0.0.1 - 550.,0.0.0.
<br />
<br />2,0
<br />
<br />0,5
<br />
<br />12 G'II
<br />~'ZOGW
<br />
<br />~'ZOOGW
<br />~'ZOG'II
<br />
<br />"-~ 1200 G'N
<br />~e ---
<br />
<br />8S%
<br />LEARNING
<br />
<br />1.0
<br />
<br /> 0,25
<br /> 0,3 0,6 0,9 1,2 2.4 3,0
<br />7 ,
<br />~ 10 2
<br /> ,ZGW a:
<br />a: 2,0 <oJ
<br /><oJ ~ ------------- ..
<br />.. f-
<br /> E ,ZOGW z
<br />,.. ~ -------- ooGw } '" <oJ
<br />Z U
<br /><oJ LEARNING ,.:
<br />u 1,0 IZ
<br />-----====:::::: IZO G'II '"
<br />,.: 0
<br />'" ~~ 1200G'M u
<br />0 >-
<br />u --- '"
<br />>- 2 a:
<br />'" 0,5 2.4 3,0 <oJ
<br />a: 0.3 0,6 0,9 1,2 z
<br />w w
<br />z
<br />w
<br />
<br />3,0 ~ 12GW
<br /> 10
<br /> c~'20GW
<br />2,0 .,; ::::::::::::::: -::::: I~OO GW } ,,.
<br /> LEARNING
<br /> f'\.. I/) I 120G'Ii 5
<br /> \;!E ----- IZOOGW
<br />1.0 3.6
<br /> 0,3 0,6 0,9 1,2 2.4 3,0
<br />
<br />RATED POWER, MW
<br />Fig. 6 Relationship between energy cost of windpower and capacity
<br />ratings of individual machines, for, various windpower goals, mean
<br />windspeeds, and experience rates
<br />
<br />projected back to obtain the energy cost for the first machine
<br />of the production run.
<br />The rationale for these numbers was that the experience
<br />rate would be atypical in the early part in the run and would
<br />tend to stabilize as the run progressed. Attention was thus
<br />focused on the bulk of the production run, for which the
<br />assumptions are most likely to be suitable. Integration results
<br />in the expression:
<br />
<br />A (nj(l+lOg2b)'._ni(I+IOg2b) )
<br />avg cents/MJ =
<br />(nf-ni) (1 +log2b)
<br />
<br />where ni and nf are the ordinal numbers of the initial and
<br />final machines, respectively, Of the mission run, and avg
<br />cents/MJ is the average cost of energy for the entire project.
<br />
<br />3 Results of Calculations
<br />
<br />The results of the calculatiops are shown in Fig. 6 and in
<br />Tables 2(a) and 2(b) for mean windspeeds of 8.0 and 10.7
<br />mis, respectively.
<br />These results show that, for the most likely situations,
<br />lowest cost windpower will be provided by machines near 0.6-
<br />MW capacity. Only when a very pessimistic experience rate is
<br />assumed does a 1.2-MW machine appear to offer any ad-
<br />vantage over an 0.3-MW machine. For windfarm locations
<br />with a high average windspeed; such as might be found along
<br />the arctic coasts of North America, the optimum machine size
<br />
<br />310 I Vol. 103, NOVEMBER 1981
<br />
<br />1.5
<br />
<br />1,0
<br />
<br />Table 2(a) Average energy cost, cents per kilowatt-hour in
<br />1976 dollars, for various capacities of single machines, ex,
<br />perience rates, and national windpower goals, with average
<br />windspeed 8.0 m/s
<br />
<br />Capacity
<br />MW
<br />
<br />Goal
<br />12DGW
<br />
<br />12DDGW
<br />
<br />12GW
<br />
<br />Average energy cost, cents/kWh
<br />9D-percent experience rate
<br />
<br />0.,3
<br />0.,6
<br />1.2
<br />2.4
<br />
<br />1.85
<br />1.67
<br />1.73
<br />2,0.2
<br />
<br />1.31
<br />I. 18
<br />1.22
<br />1.42
<br />
<br />0..94
<br />0.,86
<br />0.,92
<br />1.0.4
<br />
<br />85-percent experience rate
<br />
<br />0.,3
<br />0.,6
<br />1.2
<br />2.4
<br />
<br />1.23
<br />1.16
<br />1.26
<br />1.56
<br />
<br />0.,72
<br />0.,68
<br />0.,74
<br />1.0.5
<br />
<br />0..43
<br />0..42
<br />0..48
<br />0.,56
<br />
<br />Table 2(b) Same as Table 2(a) for average windspeed 10.7
<br />m/s
<br />
<br />Capacity
<br />MW
<br />
<br />Goal
<br />12DGW
<br />
<br />12o.o.GW
<br />
<br />12GW
<br />
<br />Average energy cost. cents/kWh
<br />95-percent experience rate
<br />
<br />0.,9
<br />1.2
<br />2.4
<br />3,0.
<br />
<br />1.59
<br />1.50.
<br />1.50.
<br />1.54
<br />
<br />1.34
<br />1.26
<br />1.28
<br />1.33
<br />
<br />1.15
<br />1.0.9
<br />1.10.
<br />I. I I
<br />
<br />9D-percent experience rate
<br />
<br />0.,9
<br />1.2
<br />2.4
<br />3,0.
<br />
<br />1.15
<br />1.10
<br />1.14
<br />1.19
<br />
<br />0.,81
<br />0.,78
<br />0.,82
<br />0.,88
<br />
<br />0.,60.
<br />0.,58
<br />0.,60.
<br />0.,62
<br />
<br />is still 1.2 MW or less. The better the experience rate, the more
<br />a smaller machine is favored. The curves are nearly flat over
<br />power ratings varying by a factor of three or more, suggesting
<br />that factors other than those so far considered may be im-
<br />portant and even decisive.
<br />
<br />4 Other Implications of Machine Size
<br />
<br />We turn now to considering how the size of large wind
<br />machines is likely to affect their entry into widespread and
<br />common use. It is instructive to consider how size and
<br />proliferation were related for two technological innovations
<br />that have greatly affected modern life, the automobile and the
<br />airplane.
<br />Each achieved acceptance of its technical feasibility on the
<br />strength of a very few machines that demonstrably worked
<br />and appeared likely to have useful applications. For each, a
<br />period of numerous entrepreneurial experiments quickly
<br />followed. These involved many inventors who improved upon
<br />the original prototypes, many producers who tried endlessly
<br />different ways of building them, many marketers who
<br />developed a broad variety of applications, and many en-
<br />
<br />Transactions of the ASME
<br />
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