The US Department of Energy's National Renewable Energy Lab has released its EWITS report.
http://www.nrel.gov/wind/systemsintegration/ewits.html

The Eastern Wind Integration and Transmission Study investigated three scenarios for supplying 20% and one for 30% of the electricity for the US eastern interconnect from wind by 2024.  This is a giant area spanning from the east coast of the US to the central plains states, excluding TX.  (The corresponding report for the western states is due out in a couple of months.)

It’s an extremely detailed study that explores the feasibility, limitations, and costs of a large system of interconnected wind farms and conventional generation.   The overall conclusion is that wind power works just fine, as long as it diluted 3:1 with dispatchable generation, but it does increase costs a bit.  The study doesn’t directly address the question of how to build an 80% carbon-free electrical system, but it would certainly appear that wind power hinders rather than helps with that task.

The EWIT  study:

  • Looked at 3 years of hourly wind and load data, and chose wind siting, the required wind capacity, transmission, fossil fuel capacity, and fossil fuel dispatch  to create a reliable system with the targeted wind energy contribution.

  • Assumes the high wind penetration is by portfolio mandate, not economics.

  • Shows that wind will increase the wholesale cost of power by 9% for the cheapest 20% scenario and 37% for 30% of total electric generation (compared to a reference case with 6% wind).  This assumes the existing Federal subsidy continues.

  • Shows that the 20% scenario that tried to build more “local wind” (including 28% offshore) on the east coast drove up wind cost by 8% compared to just transmitting most of it from the windy central plains.

  • Shows that at the assumed nuclear price of $2.9/W (and $1.75/W & $2.44/W for on & off shore wind respectively) and no price on carbon, new nuclear can not be built in the presence of the wind mandate, even though it is cheaper! (But coal still gets built).

  • Finds a much higher price for transmission than previous NREL studies, about $0.7 per Watt of nameplate wind in the cheapest scenario.  The scenarios used from 5 to 10 west to east transmission lines of 800kVDC and about 1000 miles each, plus a network of 765kVAC lines to feed them.  The scenario with more distributed wind costs more overall, but had only $0.5/W for transmission.

  • Finds a large amount of wind energy discarded due to transmission congestion, about 7% of the total for the 20% wind scenarios and 10% with the 30% scenario.

  • Tested one scenario with a $100/t CO2 tax, which they said was the amount required to replace coal with gas.  It doubled the cost of electricity, and drove down emission another 28% compared to 20% wind alone.  This scenario also allowed some new nuclear power, and led to some coal plant retirements.  They stated that a lower tax would replace coal with nuclear, but were not specific.

  • Showed that overall CO2 emissions went down, but some “baseload” (coal?) generation did shift from east to lower priced generators in the west.

Let’s hope that before too much more time passes, the US Department of Energy will finally get around to studying a more ambitious (yet achievable), 80% emissions reduction for our national electrical system.