A defining challenge for the U.S. electricity industry is to economically integrate renewable energy facilities into grid operations without sacrificing reliability. Bulk energy storage options are commercially proven technologies that enable that integration most expediently. Existing and emerging national and state policy frameworks are supporting their application in projects under development throughout the country.
At the 2010 ELECTRIC POWER Conference Keynote Session, Richard McMahon, executive director of the Edison Electric Institute, noted that renewable energy facilities account for 60% to 90% of all generation capacity with interconnection requests to six independent system operators (ISOs)/regional transmission organizations around the U.S. Now combine that startling realization with a few other sobering observations:
- Coal-fired plants face an “environmental gauntlet” that will likely shutter dozens of smaller, older power stations around the country, according to utility executives.
- Renewable energy expansion is more bipartisan than most energy issues, because it is a “domestic” resource; it is leading a recovery in domestic manufacturing and jobs; and it reduces our carbon intensity.
- Many states have renewable portfolio standards in place.
- Where many wind energy facilities operate within one balancing authority, electricity prices are often driven into negative territory because of an excess of subsidized wind power at night, nuclear plants that don’t cycle, and large disparities between off-peak and on-peak electricity demand. Wind tends to blow least (at midday) when you want it the most and the strongest (at night) when electricity demand is lowest.
- Wind facilities are frequently curtailed because of transmission system constraints or because grid operators have little reserve available to balance forecasted wind versus actual variations in output.
- Fossil units are undergoing deeper and more frequent cycling and dispatch to “fill in” around wind energy. Studies confirm that cycling costs are significant and need to be accounted for in the overall evaluation of options.
- High penetrations of wind energy may exacerbate overall emissions levels because cycling and dispatch of fossil-fueled plants usually means higher levels of emissions.
Barring a wholesale change in political sentiment, high penetrations of renewable energy in grids around the country are no longer a question of if, but when (Figure 1). Serious impacts on electricity markets, grid performance, plant operating costs, and environmental profiles are already being felt.
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| 1. PJM load and wind resources. Growth in wind energy facilities in the PJM Interconnection is accelerating, growing from a few hundred megawatts in 2006 to an expected 25 GW in 2010, and rising to almost 41 GW in 2015. The impact on the PJM system is significant. These charts display data for April 7, 2010. Source: PJM |
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