By 2020, 75% of all incremental new generation will come from zero-carbon energy in the U.S.

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 Energy information Administration beleives that we need to add about 20,000 MWs per year in the US. My guess is that as usual, EIA is wrong and this number is high. Even so, zero carbon energy will meet an increasing portion of this until at least 75% of incremental generation per year comes from zero-carbon sources.

Further, the largest problem in electricity is not 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 "NIMBY" issues pose a big problem. Instead of investing $200B (EEI's prediction) to combat this problem, this problem will be met by a mix of new transmission lines and distributed generation constructed near the largest power demand areas.

Zero-carbon energy for me includes:
solar thermal, solar electricity, central and distributed wind, geothermal, landfill gas, nuclear, and small-scale hydro.