Christian Science Monitor: At the Home and Garden Show in Augusta, Maine, on Saturday, the big attention-getter was over in the convention-center corner: a powder-blue wind turbine. With clean lines and a sleek fiberglass composite skin, the home-scale windmill was fetching enough, but it was wearing something that made it even more attractive to passersby: a bright orange sign advertising that buyers could claim a 30 percent federal tax credit for its purchase. Looking at the turbine, Bruce Cooper, a …