With air pollution and natural gas price volatility, greenfield fossil fuel power plant projects will be difficult to justify. Between now and 2020, many existing power plants will be retrofitted to produce twice the power it does today, they will not be shut down. Coal power plants will receive significant efficiency increases, increasing each plant's total capacity. However, at some point close to 2020, this process will largely be completed. The largest problem in electricity will not be generating capacity, but electricity transmission and distribution. Most of this infrastructure in the US is over 50 years old. Also, these problems are in crowded places where "right-of-way" issues pose a big problem. Instead of investing $50B (Secretary Abraham's prediction) to combat this problem, small scale generation will be encouraged to be constructed in the middle of the largest power demand areas.
Renewable/sustainable energy for me includes:
solar thermal, solar electricity, central and distributed wind, burning biomass, burning waste/garbage to energy, geothermal, landfill gas, and small-scale hydro.
Challenge Jigar Shah to a bet on this prediction!