8KW wind turbine blade material selection. HELP!!!!!

In the 1980's when tax credits were available for wind turbine and other renewable energy development lots of folks did experiments using aluminum blades, none of which were effective. Aluminum is too subject to fatigue after the repeated flexing that a wind turbine blade undergoes. ALCOA (the Aluminum Corp of America ) was even involved in quite a bit of testing with no success. Steel is totally out of the question because it is too heavy.  I do not know of any sources for verifying this information, unfortunately. There are books out there from engineering schools etc., that were doing some work during the renewable energy tax credit era but they can be hard to find now. You could also try contacting the National Renewable Energy Lab to see if they have any appropriate docs or can direct you to some.