Coal, Gas

Wind Power Spins Into Contention

Issue 2 and Volume 104.

1999 was a banner year for the wind energy industry, and 2000 promises to be just as good if not better since the renewal of the wind energy tax credit near the end of 1999.

Preliminary industry estimates show more than 3,600 MW of wind generating capacity was installed last year, bringing total worldwide installed wind capacity to 13,400 MW. This total represents an increase of more than 36 percent over the 1998 total installed capacity of 9,751 MW and the largest worldwide addition to wind capacity in a single year, according to American Wind Energy Association records.

Between 1995 and 1998, 4,893 MW of wind capacity was installed worldwide for an average annual growth rate of 27.75 percent. Wind capacity has surged from less than 2,000 MW in 1990 to 13,400 MW at the close of 1999.

These statistics seem to support European Wind Energy Association claims that wind power can produce 10 percent of worldwide energy supply by 2020, even if electricity consumption increases substantially. Denmark and Germany’s Schleswig-Holstein region are already approaching this 10 percent figure.

“The 1990s have seen Europe emerge as a world leader in wind energy development, and we expect this strong performance to continue,” said Christophe Bourillon, EWEA executive director. “Our association has set targets for Europe alone of 40,000 MW of wind capacity by the year 2010 and 100,000 MW by the year 2020.”

Bourillon attributes the surge in wind power’s popularity to concern about climate change, worries about fossil fuel supplies, and the need to sustain an ever-increasing population. “Wind energy can reduce the amount of greenhouse gases released into the atmosphere, preserve valuable fossil fuel reserves for specialized uses and help poorer rural countries develop without resorting to polluting technology,” Bourillon said. “Although there are uncertainties because of the changeable policy environment, we are projecting more than 5,000 MW of new growth in the United States over the next decade,” said Randall Swisher, AWEA executive director.

“Overall global investment in wind turbines should surpass $200 billion by 2010. The growth this past year is just the beginning of a rapid investment into renewable energy sources worldwide,” said Michael Kujawa, senior Allied Business Intelligence Inc. analyst.

*Values for U.S., UK, China and Netherlands are final. Estimates for Germany, Spain and Denmark are confirmed. Italy and Sweden are unconfirmed estimates. Additions only include projects that are installed and operating by the end of the calendar year. U.S. figures are net of retired projects. Source: American Wind Energy Association
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The top three countries added 2,582 MW of new capacity and account for almost 64 percent of total capacity additions in 1999. (See table.)

Capacity Boom

According to the AWEA’s recently released “1999 Global Wind Energy Market Report,” some 732 MW of new wind capacity and an additional 173 MW of repowering projects using new turbines to replace less efficient older machines were installed in the United States, bringing the nation’s total capacity to approximately 2,400 MW. 1999 saw wind capacity jump 40.8 percent over the previous year.

An important catalyst to this unprecedented growth was the expiration of the wind energy production tax credit in June 1999. Developers raced to complete projects before the expiration deadline. The tax credit has since been retroactively reinstated and will run through Dec. 31, 2001. Wind energy producers can continue to receive inflation-adjusted 1.5 cents/kWh tax credits for utility-scale projects. AWEA expects the continuing tax credit to spur more growth in the wind energy market.

Other driving forces included progressive state policies, especially in Minnesota and Iowa, and the movement toward customer choice and green power programs in several states. Wind energy’s relatively low cost has led more than 80 utilities to offer a wind energy-based product to customers.

“After struggling for most of the ’90s, it (wind energy) has come of age at the very end of the millennium,” states the AWEA report. “One reason for the limited activity in the mid-’90s was the uncertainty caused by deregulation of the electric sector, which caused many utilities to re-evaluate their priorities, and freeze any new investment in new capacity. In the meantime, wind technology has continued to mature, gradually convincing the electric industry that it is ready for broad deployment.”

The highest levels of development activity in the next few years are expected to be concentrated in the plains states and in Texas, which has mandated 2 GW of new renewable capacity in the coming decade. In the Northeastern region, restructuring legislation is opening the market to green power producers.

Merchant Potential

Enron Wind Corp. recently dedicated its Green Power I wind power facility near Palm Springs, Calif. The 22-turbine, 16.5 MW project was built solely to supply emerging green power markets and is the first major renewable power plant to enter California’s market since it opened to competition in 1998.

Moorhead Public Service, located 250 miles northwest of Minneapolis, chose an arctic model wind turbine generator from NEG Micon for its “Capture the Wind” green power program. (Photo courtesy of NEG Micon)
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Green Power I began producing power in June 1999. Traditionally, wind power has been sold only under long-term contract to utilities, however, the Green Power I facility was built without contract and its power is being sold through retail marketers.

The facility was developed, constructed and is operated by Enron Wind Corp. The project uses advanced Zond Z-750kW Series wind turbines. With 158 and 164 foot rotor diameters, approximately the size of the wingspan of a MD-11 jumbo jet, the Z-750kW wind turbines are the largest manufactured in the United States.

New Technologies

The U.S. Department of Energy has been working with the nation’s wind turbine industry to improve technology and lower costs since 1992. The first turbines created under these partnerships are already on the market, and a whole new generation of turbines is expected to arrive in 2002.

Two new turbines are under development. In 1994, DOE announced a $40 million program to develop a new generation of innovative utility wind turbines. The cost-effective turbines are expected to expand markets for U.S. companies in both the United States and in Europe, where competition for new wind projects is driving down costs.

Eight industry teams created concepts for new utility wind turbines rated up to 1 MW. In 1996, the National Renewable Energy Laboratory selected two firms, Zond Energy Systems Inc. and The Wind Turbine Co., to move forward with their concepts.

Zond, a subsidiary of Enron Wind Corp., is developing the A-56, which will probably be a 1 MW machine. Its architecture has not yet been determined, but it may use a direct-drive generator alone or in combination with a conventional gearbox. Significant departures from conventional design are expected, including purpose-designed airfoils and low-solidity, flexible blades with individual pitch control. Taller, low-stiffness towers are expected, as are advanced control strategies to optimize energy capture and reduce loads.

The Wind Turbine Co. is designing the WTC 1000, a lightweight, two-bladed, downwind machine. The megawatt-scale turbine will include purpose-designed blades with individual pitch control, a variable coning rotor, highly integrated structure and drivetrain, load-mitigating control strategies, simplified fluid systems, and an extremely tall guyed tower. The WTC is targeted for applications in the Midwestern states.

DOE is also working with three small turbine manufacturers, selected through competitive solicitation, to improve their turbines. The goal is to develop tested systems up to 40 kW in size that achieve a cost/performance ratio of 60 cents/kWh at sites with annual average wind speeds of at least 12 miles per hour. Cost/performance ratio is defined as the initial capital cost of the turbine divided by its annual energy capture.

Bergey Windpower Co. is working to improve cost/performance ratio for its BWC Excel 40 by designing a turbine with minimal maintenance requirements. The BWC Excel 40 is a 40 kW turbine targeted for battery charging in the village power market. It is a three-bladed, upwind, variable-speed machine with a direct-drive permanent-magnet alternator. Rotor blades will be pultruded fiberglass in three lengths for use in different wind regimes. The guyed lattice towers will be available in three heights. Projected cost/performance ratio is 38 cents/kWh. DOE is funding $1.21 million of the research.

WindLite Corp. is developing an 8 kW, variable-speed, direct-drive machine with a rotor diameter of 23 feet. The turbine uses a wound-rotor generator and proprietary controller that significantly increases its battery-charging efficiency compared to permanent-magnet generators. The projected cost/performance ratio for the WLC 7.5 is 46 cents/kWh. DOE is providing $1.43 million in funding.

World Power Technology makes six small turbine models. Its Windfarmer, a 7 kW battery-charging wind turbine, is a three-bladed, upwind, variable-speed machine using a direct-drive, permanent-magnet generator. Fiberglass blades will be used on a 16-foot diameter rotor. The machines will use a unique, patented angle-furling governor for protection in high winds. World Power is also developing a counter-weighted, tilt-down 90-foot tower. Projected cost/performance ratio is 59 cents/kWh. DOE is providing $1.25 million in funding.

Big Spring Keeps on Turning

As early as 1993, TXU Electric and Gas investigated the level of demand for renewable energy in Texas. Encouraged by the enthusiasm of its customers toward green energy, TXU unveiled plans for the $40 million Big Spring wind power project near Midland in December 1998. Developed by York Research, the project has 46 turbines with a total capacity of 34 MW. The final phase, completed in April 1999, saw the commissioning of the largest commercial wind turbines in the world-four Vestas V66 turbines standing approximately 260 feet tall above the elevated plateau of west Texas ranch land.

TXU believes that the project is testament to the fact that as power technologies advance, electricity generated by renewable resources will become more common and economic.

The Big Spring project is built on mesas, rising 195 to 295 feet above the surrounding areas. The winds accelerate as the move up over these mesas. Annual average hub-height wind speeds range from 18.4 to 22.2 mph over the site.

There are three phases to the site. Phase I has 16 Vestas V47 660 kW turbines, Phase II has 26 Vestas V47s, and Phase III has the four Vestas V66 1,650 kW turbines.

Projected annual electricity generation for Big Spring is 117 million kWh.

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Both turbine models use three rotor blades of epoxy and fiberglass composite. Crosswind separation of the machines is nominally 3.5 rotor diameters. Row-to-row spacing of the machines exceeds 10 rotor diameters to minimize the impact of turbulence from adjacent rotors.

The turbine control system monitors turbine starts and stops under normal operating conditions and also protects the turbines under extreme emergency conditions such as faults caused by a loss of grid load while under power or a component failure. In addition, the system manages the power output of each turbine by pitching the blades and changing the generator slip to maximize energy production while minimizing loads at wind speeds greater than 31 mph.

The control system is operated by a digital computer using Vestas-developed programs. Portions of the system are located in the base of the tower and in the nacelle of the wind turbine. These are linked by fiber optic lines to minimize interference and damage from lightning.

A key feature of the control system is OptiSlip, which controls loads and spikes from the turbines under high wind speeds. OptiSlip allows the turbine to operate in a similar way to a variable speed machine, preventing the drive line of the machine from experiencing torque spikes.