Category Renewable Energy Technology Characterizations

Land, Water, and Critical Materials Requirements

As demonstrated in Table 10, the amount of land required for windfarms depends on turbine size and number, turbine spacing (distance side-by-side and between rows), and the number of rows. The range of land use per MW of installed capacity in Table 10 covers two scenarios for turbine spacing: 2.5 r otor diameters (side-by-side) by 20 diameters between rows, and 5 diameters (side-by-side) by 10 diameters between rows. These ranges are shown for three array configurations of 5 rows of 10 turbines (more common in flat areas), 2 rows of 25 turbines, and a single row of 5 0 turbines (more common on ridged sites). A setback of 5 rotor diameters is assumed around the perimeter of the windfarm...

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Uncertainty

Uncertainty reflected in the +/- ranges in Table 1 comes from two sources. The first is the uncertainty associated with the accuracy of the value, e. g., uncertainty of outcome of R&D. The second is from the normal variation in data values for projects, such as the cost of land for different projects.

Reliability

Reliability and durability are reflected qu antitatively in several ways in this characterization. First, availability is already at high levels for given c urrent initial turbine cost, O&M cost, and system lifetime. Second, the decline of annual O&M costs after 2005 reflects increased reliability. The decline in per-kWh O&M costs between 1996 and 2005 is assumed to be due more to increased energy output per turbine than increased levels of reliability...

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Balance of Station Costs

Balance of Station (BOS) costs include foundations, control/electrical hardware, site preparation, electric collection system and transmission lines, substation, windfarm control and monitoring equipment, O&M facilities and equipment, initial spare parts, shipping, resource assessment, surveying, legal counsel, project management and administration, permits, construction insurance, and engineering services. Since land cost is listed on Table 1 as a percent of revenue and not an initial capital cost, it is discussed in the O&M section.

A range of approximately 25%-33% of total project costs was estimated for BOS costs in a recent design study based on a 50 MW windfarm using 275 kW wind turbines [21]...

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Effects of Volume on Cost

Although lower costs are not an automatic result of higher sales volume, there are several specific volume effects tha t reasonably can be expected to lower future turbine and windfarm costs. First, increasing sales may allow the industry to employ new manufacturing technologies that lower production costs. Second, there is an established learning effect in

similar products that indicates product costs decrease as cumulative sales increase. Third, as annual production volume increases, there may be an opportunity for larger volume discounts for off-the-shelf turbine components. Reference 35 discusses these effects in more depth.

Table 8 summarizes the key qualitative subsystem cost drivers described above.

Table 8. Major subsystem cost drivers.

1996-2000

2000-2005

2005-2030

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Current Technology (1996)

Current Performance: Operational data for current technology is widely available from California windfarms and other locations around the world. Performance indicators for the base year are a composite of commercial technology available in 1996, including turbines from the DOE Near-Term Product Development Project [21-23] and from several othe r manufacturers [24]. These turbines include fixed and variable speed designs, most of which use one or more low cost, induction generators. The 1996 technology composite is distinguished from earlier technology, late 1980s/early 1990s, by the substantial use of power electronics for power conversion and/or dynamic braking, and by the use of advance d airfoil designs. Projects using these t ypes of technology currently exist...

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Performance and Cost Discussion Key Assumptions

Expected economic life (years): The expected economic life for the windfarm project is 30 years, based o n

manufacturers’ field experience of nearly 15 years and stated design goals [20]. Periodic replacement or refurbishment of major subsystems such as rotor blades or generator windings are assumed to be necessary during the 30-year period, although not all manufacturers claim to require blade replacement in that period. Some researchers feel that sufficient data on component cycle loads, composite material per formance prediction, and extended operation over a 30-year period do not currently exist to make accurate predictions of lifetime as long as 30 years.

Construction financing costs: These are not included in the $/kW capital cost estimates in Table 1...

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Evolution Overview

Table 2 summarizes the projected composite technology path. Figure 2 shows the associated major technical trend s expected in wind turbine development. One of the concepts the figure illustrates is that while there may be majo r innovative advances in the technology which drive COE down, simultaneously, there will be an ongoing process o f incremental optimization. Major inn ovation is reflected by "jumps" in both size and subsystem type from 1995 to 2000, and again from 2000 to 2005. The optimization process is shown as the bottom arrow "feeding" the major improvements above. The "jumps" in technology shown in the figure denote a broad technology development trend, but they do no t indicate that a single design path is projected...

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Performance and Cost

Table 1 summarizes the performance and cost indicators for advanced horizontal wind turbines in windfarms bein g characterized in this report.

Table 1. Performance and cost indicators.

Base Case

INDICATOR

1996

2000

2005

2010

2020

2030

NAME

UNITS

+/- %

+/- %

+/- %

+/- %

+/- %

+/- %

Plant (windfarm) Size

MW

25

37.5

50

50

50

50

Turbine Size

kW

500

750

1,000

1,000

1,000

1,000

Hub Height

m

40

60

70

80

90

100

Rotor Diameter

m

38

46

55

55

55

55

Swept Area

m2

1,134

1,662

2,376

2,376

2,376

2,376

Performance

Annual Energy delivery

+5/-15

+10/-20

+10/-25

+10/-25

+10/-25

+10/-25

Class 4 (plains...

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