Hydro, solar, wind, geothermal are all energy sources that are perpetual. While there is a cost to connecting to, harvesting, and maintaining the flow of this energy, the energy itself is perpetual. The same can even be said of fire based and nuclear based energy. For in both cases the energy equations are always perpetual. Once a fire is started it will continue perpetually. There might be a cost associated with providing and maintaining the fuel, but the energy equations by themselves are perpetual. As in all these cases, environment flows or stored energy is harvested, we will also be discussing how this method can apply to cold fusion and other 'zero point' energy.
