Josh+and+Rich's+Page

Green Materials:

types: crystalline silicon amorphous silicon
 * PV cells**

types: laminate fiberglass laminate fiberglass with wood core laminate fiberglass with ___ core
 * Turbine Blades**

See a great aritcle from www.about.com on the design of turbine blades []

They have a good connection to defects and the life of a blade, "This method has been used to fabricate many types of composite structures, such as boats and car bodies, but it tends to create small imperfections that cause premature failures of wind turbine blades," Ashwill says. A colleage adds, "A gust induces extraordinary loads into the blades that can significantly reduce their ability to function reliably. A single large event can reduce the life of a turbine blade by half." By studying data from the experiment

An industry member (LM Glass Fiber) discusses how they test their blades [|http://www.lmglasfiber.com/dalmg/turbine_blade.htm] A paper on the erosion of blades by solid particle impact (dust, etc) on blades. This paper mainly discusses how metal blades in industry are marginalized, but it isn't much to consider what it would do to wind turbine in a dusty area. []

A paper discussions fatigue issues in blades used in the field, and proposes solutions and gives guidelines to use. [[http://www.coe.montana.edu/composites/documents/SAMPE%202008.pdf|http://www.coe.montana.edu/composites/documents/SAMPE%202008.pdf

]] Wikipedia Article (see section on blade materials) http://en.wikipedia.org/wiki/Wind_turbine_design

Blade materials New generation wind turbine designs are pushing power generation from the single megawatt range to upwards of 10 megawatts. The common trend of these larger capacity designs are larger and larger turbine blades. Covering a larger area effectively increases the tip-speed ratio of a turbine at a given wind speed, thus increasing the energy extraction capability of a turbine system. [2] Current production wind turbine blades are manufactured as large as 80 meters in diameter with prototypes in the range of 100 to 120 meters. In 2001, an estimated 50 million kilograms of fiberglass laminate were used in wind turbine blades. [3] New materials and manufacturing methods provide the opportunity to improve wind turbine efficiency by allowing for larger, stronger blades. One of the most important goals when designing larger blade systems is to keep blade weight under control. Since gravity scales as the cube of the turbine radius, loading due to gravity becomes a constraining design factor for systems with larger blades. [4] Current manufacturing methods for blades in the 40 to 50 meter range involve various proven fiberglass composite fabrication techniques. Manufactures such as Nordex and GE Wind use a hand lay-up, open-mold, wet process for blade manufacture. Other manufacturers use variations on this technique, some including carbon and wood with fiberglass in an epoxy matrix. Options also include prepreg fiberglass and vacuum-assisted resin transfer molding. Essentially each of these options are variations on the same theme: a glass-fiber reinforced polymer composite constructed through various means with differing complexity. Perhaps the largest issue with more simplistic, open-mold, wet systems are the emissions associated with the volatile organics released into the atmosphere. Preimpregnated materials and resin infusion techniques avoid the release of volatiles by containing all reaction gases. However, these contained processes have their own challenges, namely the production of thick laminates necessary for structural components becomes more difficult. As the preform resin permeability dictates the maximum laminate thickness, bleeding is required to eliminate voids and insure proper resin distribution. [3] A unique solution to resin distribution is the use of a partially preimpregnated fiberglass. During evacuation, the dry fabric provides a path for airflow and, once heat and pressure are applied, resin may flow into the dry region resulting in a thoroughly impregnated laminate structure. [3] Epoxy-based composites are of greatest interest to wind turbine manufacturers because they deliver a key combination of environmental, production, and cost advantages over other resin systems. Epoxies also improve wind turbine blade composite manufacture by allowing for shorter cure cycles, increased durability, and improved surface finish. Prepreg operations further improve cost-effective operations by reducing processing cycles, and therefore manufacturing time, over wet lay-up systems. As turbine blades are approaching 60 meters and greater, infusion techniques are becoming more prevalent as the traditional resin transfer moulding injection time is too long as compared to the resin set-up time, thus limiting laminate thickness. Injection forces resin through a thicker ply stack, thus depositing the resin where in the laminate structure before gelatin occurs. Specialized epoxy resins have been developed to customize lifetimes and viscosity to tune resin performance in injection applications. [5] Carbon fiber-reinforced load-bearing spars have recently been identified as a cost-effective means for reducing weight and increasing stiffness. The use of carbon fibers in 60 meter turbine blades is estimated to result in a 38% reduction in total blade mass and a 14% decrease in cost as compared to a 100% fiberglass design. The use of carbon fibers has the added benefit of reducing the thickness of fiberglass laminate sections, further addressing the problems associated with resin wetting of thick lay-up sections. Wind turbine applications of carbon fiber may also benefit from the general trend of increasing use and decreasing cost of carbon fiber materials. [3] Smaller blades can be made from light metals such as aluminum. Wood and canvas sails were originally used on early windmills due to their low price, availability, and ease of manufacture. These materials, however, require frequent maintenance during their lifetime. Also, wood and canvas have a relatively high drag (low aerodynamic efficiency) as compared to the force they capture. For these reasons they have been mostly replaced by solid airfoils.

made of: fiberglass

must resist: fatigue erosion

must have: low mass (mass increases by the radius cubed)


 * Biodiesel storage tanks**