When we think of decentralized home energy there are a lot of options out there. We can choose, water, solar or wind energy. When it comes to fitting your home with some kind of home energy device people usually think of solar energy, both water and wind power seem to have to many disadvantages and seem to be to costly. Well that’s history now, all over the world company’s are coming up with residential wind mills, wind energy will probably catch on faster then power companies would like. One of these wind mills originally designed by a Dutch engineer is the Energy Ball. By curving the rotor blades in such a way that the center of the mill depressurizes the wind turbine essentially turns in to a wind magnet. In the average wind generator you can see an energy return of about 60% but the unique blade construction of the Energy ball gives a return of about 85% making it very efficient. The other advantage of these types of blades is the noise reduction making the energy ball perfect for residential areas. These wind mills come in 3 types 2 of witch are not for sale yet, the finished one is the V100 this small wind energy device weights about 30KG and will on average produce about 500W with 220V this will not power your whole house but can reduce your electrical bill by about 15%. Assuming the electricity prices wont suddenly rise sky high it takes about 10 years to earn back your investment. But after that its free energy. The energy ball doesn’t require a lot of maintenance just a couple of new rotors every 10 years or so and it will last you for about 25 years by witch time there is probably an other free energy device on the market. The energy ball will set you back around €3000,- and is one of the cheaper residential windmills I came across.