Of all of the alternative energy sources discussed in this book, wind and solar have the most potential. It is a proven technology, it is growing fast, it already occupies a significant share of the energy market, and costs continue to decline rapidly.
Wind power is well into the world-wide implementation phase. There is no reason to believe that its growth will not continue. The sketch shows solar power as being in Phase IV: Implement (see Project Status for the background to this sketch).