The Energy Information Administration's 2011 outlook released on April 26 says that with growing electricity demand and the retirement of 39 GW of existing capacity, 223 GW of new generating capacity (including end-use combined heat and power) will be needed between 2010 and 2035. 

Natural-gas-fired plants will account for 60% of capacity additions between 2010 and 2035, compared with 25% for renewables, 11% for coal-fired plants, and 3% for nuclear. Escalating construction costs have the largest impact on capital-intensive technologies, including nuclear, coal, and renewables.

However, federal tax incentives, state energy programs, and rising prices for fossil fuels increase the competitiveness of renewable and nuclear capacity. In contrast, uncertainty about future limits on greenhouse gas emissions and other possible environmental regulations reduces the competitiveness of coal-fired plants.

Capacity additions also are affected by demand growth and by fuel prices, which are uncertain. Total capacity additions from 2010 to 2035 range from 172 GW in the Low Economic Growth case to 290 GW in the High Economic Growth case. With higher natural gas prices, fewer natural-gas-fired plants could be added.

Annual capacity additions in 2010, 2011, and 2012 will average 17 GW per year, with at least 40% of that capacity already under construction. Of those early builds, about 46% are renewable capacity built to take advantage of federal tax incentives and to meet state renewable standards.

Annual builds will drop significantly after 2012 and remain below 7 GW per year until 2025. During that period, existing reserves are adequate to meet growth in demand in most regions, given the earlier construction boom and relatively low demand growth following the economic recession. Between 2025 and 2035, average annual builds increase to 11 GW per year, as excess reserves are depleted and total capacity growth is more consistent with demand growth. About 80% of the capacity added in the period is natural-gas-fired, due to higher construction costs for other capacity types and uncertain prospects for possible future limitations on greenhouse gas emissions.