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ISO New England Releases the New England Wind Integration Study

June 3, 2011

Electricity grids, power supply portfolios, and power markets are designed to efficiently deal with the variability of electric demand. In New England, this is particularly true due to the substantial role of flexible hydroelectric and natural-gas-fired generation, and hydroelectric pumped storage capacity. However, adding significant amounts of wind power to a region's electric grid can impose new demands on the system—often referred to as integration issues or challenges. These can include impacts on operations, scheduling, operating reserves, regulation, forecasting, dispatch, transmission, and emissions. While many of these impacts are often similar in nature to those imposed by load variations or unplanned outages, their impacts—particularly at high penetrations—can differ in magnitude and frequency. As a result, it is important to understand the potential impact of adding material amounts of wind power to the grid to anticipate and mitigate any undesirable impacts.

Two years after rolling out the New England Wind Integration Study (NEWIS) to the ISO New England (ISO-NE) Planning Advisory Committee, the final NEWIS report was released on December 17, 2010. The goal of NEWIS was to look into the future and determine the operational, planning, and market impacts of integrating substantial wind generation resources into the New England Balancing Authority Area. In order to achieve this goal, the study was also designed to make recommendations for mitigating any negative impacts on the region's electricity system of increased wind integration.

As of October 2010, approximately 270 MW of utility-scale wind generation were operating in ISO-NE and another 3,200 MW were in the interconnection queue. NEWIS studied a number of scenarios for future penetrations far in excess of what is in place today, ranging from 1,140 MW to 12,000 MW of installed wind capacity. These study levels do not represent the amount of wind generation that is expected or possible within New England but rather are used to answer a number of "what if" questions relevant to the long-term planning process over a wide range of potential futures.

Some of the key findings of the study include:

  • The study results show that New England could integrate even the highest amount of wind studied (approximately 24% of the region's energy being provided by wind power) assuming a number of transmission upgrades and no significant retirement of supply-side and demand-side resources able to provide flexibility to the system.
  • Given the way that the NEWIS model was set up, the wind generation predominantly displaced natural gas in the market simulations and displaced coal generation on occasion. The model did not allow for the wind to displace hydro or nuclear resources.
  • The degree to which regulation requirements would increase is related to the accuracy level of short-term wind forecasting. As wind forecasting capabilities improve, the additional regulation requirements would decrease. Using currently available wind forecasting accuracies and the most conservative of three approaches to estimating regulation requirements, NEWIS found that average regulation requirements would increase from 82 MW in the base case to 100 MW in the 1,140-MW wind case to 315 MW in the 12,000-MW wind case. The study also suggests that this incremental increase in regulation requirements should not be counted toward Ten Minute Non Spinning Reserve requirements.
  • The required amount of incremental reserves varies based on the percent of nameplate wind energy being produced at a given time rather than by time of day and season as with load reserves. NEWIS suggests that until wind penetration surpasses 4,000 MW, the existing process for scheduling regulation should be adequate.
  • Ramping capabilities were shown to be sufficient in the case where wind energy output drops and non-intermittent generation is needed to ramp up. While a small number of cases were identified in which there would be insufficient capability for non-intermittent resources to ramp down sufficiently when wind energy increased, the report also concluded that this situation can be easily managed by limiting wind generation in those minimum generation emergency scenarios (a practice recently adopted in New York).
  • With 20% of New England's energy provided by wind power, NEWIS found NOX emissions would be reduced by approximately 26%, SOX emissions reduced by 6%, and CO2 emissions reduced by 25%.

Wind integration issues, especially the New England Wind Integration Study, have been discussed with ISO's Planning Advisory Committee (PAC).

—Julie Jones