What it comes down to is that any energy you gain from wind is either causing you to go slower or your legs to work harder to keep the same speed. If the turbine does not increase drag, then it is in effect not a wind turbine and cannot produce any energy. Once you factor in the efficiency of the turbine, and the efficiency of the bicycle, and the efficiency of the battery, and the efficiency of the power converter, you are probably working an extra 10 watts or more for every watt of electricity you output. It's far better to a) use batteries, b) charge from a wall outlet while you eat lunch, or c) throw out whatever it is that needs electricity.