But when you look at manufacturers it seems that a 500W Kaplan turbine requires 3 metres of head and costs almost US$4,000. http://www.aurorapower.net/products/

But when you look at manufacturers it seems that a 500W Kaplan turbine requires 3 metres of head and costs almost US$4,000. http://www.aurorapower.net/products/categoryid/4/list/1/level/a/productid/235.aspx http://www.aurorapower.net/products/categoryid/4/list/1/leve... (Linked from Wikipedia, certificate is invalid :/ ) A 500w version of this turbine requires only 1.2m of head and costs $1,550 including inverter. I think that's significant, especially for the developing world.