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New RIM Technique to Reduce Costs of Decentralized Wind Power

11 June 2004

The manufacturing technique used to make large truck beds, fenders and bumpers will soon be put to use producing medium-size wind turbine blades.

The U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Golden Field Office, has awarded a $1.5 million development grant to a world-renowned Concord-based boatbuilder and an Amherst-based wind power engineering consortium that grew out of the UMass Wind Furnace project of the 1970s.

The collaborative of engineers and manufacturers headed by Dr. Woody Stoddard, of Amherst, a wind energy expert and Senior Engineer at Composite Engineering, Inc. in Concord, hopes to adapt the industrial “RIM” technique to the manufacture of 7.5-metre windmill blades. Their ultimate goal is to make widespread decentralized wind power truly cost effective in the 21st century. If they are successful, it may mean the beginning of a solid alternative to, and independence from fossil fuels for mankind’s energy needs for farms, ranches, small businesses, and municipal utilities.

The group will design and manufacture prototype wind turbine blades using a method called Reaction Injection Moulding, or RIM. RIM has been used for the last 30 years to make durable large-scale plastic products such as truck fenders, vehicle dashboards, and cab roofs for farm combines. RIM’s accuracy, low cost, repeatability and high material strength will now be applied to wind turbine blades, and the engineers are confident that RIM-made blades will be stronger, lighter, and more efficient than those currently in use and, with mass production, can be made at a much lower cost.

Wind turbine blades must weather huge forces. In contrast to airplanes and helicopters, which can avoid encounters with storms, high winds and turbulence, stationary wind turbines must stand fast against such forces over an average lifetime of 20-plus years. In addition, wind turbines are often sited in high wind areas in order to harvest maximum wind power. The resulting mechanical stresses can be huge, and deriving a reasonably long life from the blades has been a continuing challenge for the wind turbine industry.

Traditionally wind turbine blades have been produced by fibreglass hand-lay-up, a laborious process that results in strong but costly blades. This process has not changed substantially since the rebirth of wind energy in the 1970’s, and is true even for the largest “super-rotor” blades now being produced by utility wind turbine manufacturers such as General Electric in the U.S., Vestas in Denmark, and Nordex in Germany.

During the 1980’s, builders of small wind turbines (those producing less than 100 kilowatts and 65-feet or less in diameter) provided many of the machines used in the first large wind farms, in places such as California’s Altamont, San Gorgonio and Tehachapi Passes, as well as machines for U.S. off-grid and agricultural sites. The California wind farms now have over 2,500 such turbines still in service after over 20 years of continuous operation. These Danish-designed turbines have surprised most technical observers with their durability and longevity, but most are now requiring new blades to continue operating. This energy market’s constant need for revenue has meant few dollars have been available for technical improvements.

The bulk of federal research dollars over the past 38 years has been directed instead towards large utility size turbines, with blades of up to 160-feet, such as those proposed for Nantucket Sound.

DOE’s new research initiative for small wind turbines is intended to serve residential and small business uses in grid-connected markets throughout the United States. Says Dr. Stoddard: “We now have decades of experience on the farm-sized windmill, and it is time to put our collective expertise into an appropriate reliable product for the far-sighted farm, ranch, small business, and municipal energy markets.”

Stoddard and his “Wind Furnace Cadre” of engineers have assembled a team of high-performance industry partners, including Bayer Polymers (Pittsburgh PA), a division of Bayer Corporation and one of the world's largest producers of polymers and high-performance plastics; GI Plastek, a leading RIM manufacturer; Amadas Industries, a manufacturer of specialized agricultural equipment with broad ties to the national agricultural market; and American GFM a respected builder of specially designed machine tools.

Principal sub-contractors on the project are Louis J. Manfredi Consulting, SweetBriar and Syncretek LLC.

Prime Contractor for the 22-month project is Composite Engineering, Inc. (CEI) of Concord MA, an innovative leader in high performance composite manufacturing (including world-class Van Dusen Racing Boats’ hulls, kayaks, carbon fibre masts and spars).

Wind turbine parts and blades have been part of CEI’s work since the mid-1970’s, when the principals led the original design team which built the Wind Furnace on Orchard Hill at the University of Massachusetts Amherst campus, under the direction of the late Prof. William E. Heronemus, an international figure and pioneer in U.S. wind power. Since 1976, when the UMass windmill was erected, these and other members of the UMass graduate design team (now locally called the “Wind Furnace Cadre”) have either founded or worked with virtually every wind power company and project operator in the world. Today most of these individuals are located in Massachusetts, and are working together, for the first time, on this project.

A major focus of the DOE Wind Program is the development of wind turbine technology that is cost effective for use in most areas of the U.S. with lower wind speeds than are currently economically viable, such as the vast U.S. interior. RIM blades that are mass produced can lower the cost of energy by wind power to the point where a typical Great Plains farmer can have a simple payback period of less than four years for the cost of his wind turbine.






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