Commercial Wind Turbine Systems and Applications - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 260

Table 4-0. Utility Cost Effects Resulting from Wind Power Penetration

Year Utility study Penetration

of wind
power

Costs ($/MWh)

Regulation Load

following

Unit
commitment

Gas
supply

Total

2006 MN-MISO 32% NA NA NA NA 4.4

2007 Avista Utilities 2 30% .43 4.40 3.00 NA 8.84

2003 We Energies 29% .02 0.5 .75 NA 2.92

2007 Idaho Power 20% NA NA NA NA 7.92

2005 PacifiCorp 20% 0.00 .60 3.00 NA 4.60

2006 Xcel-PSCo 5% 0.20 NA 3.32 .45 4.97

2007 Arizona Public

Service

5% 0.37 2.65 .06 NA 4.08

2004 Xcel-MNDOC 5% 0.23 NA 4.37 NA 4.60

2007 Puget Sound

Energy

0% NA NA NA NA 5.50

2006 CA RPS 3 4% 0.45 Trace Trace NA 0.45

2003 Xcel-UWIG 3.5% 0.00 0.4 .44 NA .85

Highest costs over 3-yr evaluation period
2 Unit commitment includes costs of wind forecast errors
3 Regulation costs are 3-yr average

A study of the generation and transmission systems for Ireland examined energy portfo-
lios that contained up to 59 percent renewable, mainly wind energy. This analysis showed
that there was little difference in cost (less than 7 percent) among the various portfolios. For
a portfolio with 36 percent renewable content, 70 percent to 80 percent of the investment cost
could be recovered directly from the electricity market [Ireland 2008]. In addition, there
could be revenue from carbon reduction credit sales.

Transmission System Expansion

The power grid in much of the United States today is characterized by mature, heav-
ily loaded transmission systems. To move electricity to the major load centers from the
projected new wind power plants will require new and expanded transmission lines. Both
thermal- and voltage-related constraints affecting regional power deliveries have been well
documented on systems operating at voltages up to and including 765 kV. In the long term,
a mature system facing growing demands is most effectively strengthened by introducing
a new, higher voltage class, both AC and DC. This approach can provide the transmission
capacity and operating flexibility necessary to achieve the goal of a competitive electricity
marketplace with wind power as a major contributor. A recent study by American Electric
Power concluded that an additional 9,000 miles of high voltage lines will be required in
order for wind power to generate 20 percent of the U.S. electrical load [AEP 2007].