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Northern Power 2.3

Wind for Schools Program

Turbine Configuration

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Community Wind Basics

WHY GO GEARLESS?

Community Wind Power Basics

Common Applications

Case Studies

Northern Power 100

:: Turbine Aesthetics

Project Economics

Step by Step

See Also

:: The Gearbox Problem (PDF)

Gearless is Better

For decades, wind turbine design has been based on a conventional gearbox architecture. But the need to move away from gearbox-laden designs is well-known throughout the industry. High failure rates have had far-reaching effects and caused concern for many years.

“Over 80% of the profit warnings in the wind turbine manufacturing industry have come from gearbox issues, primarily malfunctioning bearings but also unforeseen issues with various gearbox designs.” Merrill Lynch Wind Industry Overview, August 2007

WHAT CAUSES GEARBOXES TO FAIL?

Gearboxes are problematic by the very nature of the numerous moving parts and subsystems that are required for their operation and the demanding nature of the wind turbine application itself. Bearings have also been targeted as a possible weak link.

It actually shouldn’t be surprising that gearboxes have so many failures, especially if you think about it in terms of something we all know – car transmissions. A car transmission is functionally similar to a wind turbine’s gearbox. Expecting a wind turbine’s gearbox to last for 20 years of continuous operation would be like expecting a car’s transmission to last for 4 million miles. Most would agree that is an unreasonable expectation.

WHAT OTHER PROBLEMS DO GEARBOXES PRESENT?

Even in the year when a turbine’s gearbox has not failed, owners of gear-driven wind turbines are presented with other serious and costly issues. Of greatest impact are noise and continuing maintenance.

Noise: A turbine’s gearbox is a major contributor of machine noise. While somewhat problematic in large wind power production facilities, turbine noise is a much more serious issue in community-based wind power applications where turbines are sited in the places where people live and work.
Frequent and complex maintenance: Often multiple times per year, maintenance crews need to be dispatched to care for the gearbox. Hydraulic fluids, bearings, slip rings, pumps and clutches necessitate a somewhat complex maintenance and operational support program.

“One recent report says retrofits of gearboxes were necessary at all 30 turbines in an offshore farm - after less than two years. In another case many turbines were already on their second or third gearbox retrofit after only 5 years. Gearbox replacement costs are as much as $300,000 per failure.” North American Windpower June 2006

HIGH FINANCIAL RISKS FOR DEVELOPERS

The frequent maintenance requirements and multiple (and costly) gearbox replacements have certainly proven problematic for developers of large wind power production facilities. Most wind farm developments today have maintenance teams in place to maintain and replace gearboxes. Many economic models factor in total gearbox replacements every 5-7 years on each turbine. The financial risk gearboxes represent is only somewhat mitigated by the large number of turbines in a major wind power production facility and developers’ ability to amortize personnel, equipment and consumables costs across a fleet of turbines.

CRIPPLING EFFECTS FOR COMMUNITY WIND APPLICATIONS

“Gearbox failures account for the largest amount of downtime, maintenance, and loss of power production. These costly failures can total 15-20% of the price of the turbine…” Renewable Energy World, September 2008

Demanding gear-laden wind turbines pose great challenges to the community scale adoption of wind turbines for schools, private businesses, municipalities, and farms. The costs associated with maintaining gear-driven wind turbines create an insurmountable burden to these community wind applications, which typically host only 1 or 2 wind turbines and cannot afford to employ maintenance crews or fund costly gearbox assembly replacements. Turbine down time can also lead to poor public perception for your wind project.

Gearbox turbines were simply not designed with the community application in mind—they are noisier, costlier and require more support.

NORTHERN POWER SYSTEMS BRINGS A GEARLESS FUTURE

Our country and the world face a new energy landscape. Today’s wind power production facilities and community wind applications require a new technology – one that far surpasses the antiquated and inefficient wind turbine designs of the past. With more than 30 years in the wind industry, the Northern Power Systems team embraced these challenges and the idea of a streamlined and elegant turbine architecture based on the idea that less is more:

Less subsystems, more reliability
Less moving parts, more energy
Less maintenance, more savings

It is this philosophy that formed the basis for the advanced gearless technology of the Northwind 100 wind turbine. By eliminating the gearbox architecture and the need for the many subsystems that supports its functions, Northern introduced a vastly simplified and ultra-reliable gearless technology that results in better energy capture, quieter operation and significantly lower operation and maintenance costs—an ideal combination for the community wind application.

Get more details and industry references in our WHITE PAPER: “The Gearbox Problem”