Wind energy and the summer doldrums 

Massive wind turbines now stand upon numerous ridgetops in central Appalachia, and despite the sluggish economy and uncertainty as to whether certain federal tax incentives for renewables will continue, proposals for new wind projects in the region continue to emerge. Setting aside the various detrimental impacts to wildlife, viewsheds and nearby residents of “industrial” or “gridscale” wind facilities, one is pressed to ask what we have gotten in return in terms of capability to generate electricity or to offset emissions from conventional power plants using fossil fuels. The latter consideration is beyond the scope of this article, but a brief look at generation statistics from this summer reveals industrial wind’s scant contribution to the grid during peak demand for electricity in the region.

Following the passage of the federal Energy Policy Act of 1992 and the issuance of several orders afterward by the Federal Energy Regulatory Commission, PJM Interconnection, a “power pool” for various electric utilities since 1927, was christened a regional transmission organization (“RTO”). As an RTO, PJM coordinates the transmission of electricity and manages a wholesale power market across all or parts of 13 states and the District of Columbia. Over 60 million people reside within the PJM region, which encompasses all of Pennsylvania, West Virginia and Maryland, as well as most of the state of Virginia.

The major electric utilities serving end-use customers in the region all have membership in PJM, and many of these entities or their corporate parents also participate in PJM as “transmission owners” which retain ownership of their high-voltage power lines, yet which have transferred “functional control” of those lines to PJM. PJM plays many roles as an RTO, but key in this context is its function in balancing the output of electricity from generating units connected to its grid with the demand for electricity of customers within its territory (the latter often referred to as “load”). Once on the transmission grid, power generated in West Virginia, for example, becomes indistinguishable from electricity generated elsewhere, so PJM’s balancing act is generally performed without regard to state lines.

During the summer, peak load for PJM tends to occur in mid to late afternoon, when high temperatures prompt a surge in the use of air conditioning. Saturday, July 7 of this year is an excellent example of this phenomenon, as temperatures that day hit 100ºF across most of the PJM footprint, including in Morgantown, West Virginia. For the hour ending at 5:00 p.m. Eastern time on July 7, PJM recorded an official all-time Saturday peak load of 147,905 megawatts (MW). Based on actual observations available on PJM’s online eData system that day, a comparison of customer load and aggregate wind generation (including every wind energy facility in service at the time in PJM) appears below:

During this span of four hours of record heat, the contribution of wind energy facilities in PJM to customer demand never exceeded 0.57% of that figure. Peak aggregate wind generation for July 7 reached only 1,712 MW, and not until 11:53 p.m. Eastern time, well after load had receded substantially from its late afternoon apex. Adam Keech, Director of Dispatch for PJM, reported that, although some baseload generators, such as large coal-fired and nuclear units, had to scale back somewhat on output due to operational and environmental temperature constraints during the afternoon of July 7, PJM ran 16,000 MW of combustion turbines (most running on natural gas) to handle the peak. As on many summer days in PJM, on July 7 wind energy made no meaningful contribution to mitigating dependence on fossil fuels to generate electricity.

Wind energy performance in PJM on the afternoon of July 7 is particularly significant when compared to the total generating capacity of wind energy units in PJM. As of January 31, 2012, 5,230 MW of wind energy capacity was in service in PJM. Even taking into account that some turbines could have been out of service for maintenance on July 7, the facts remain that actual wind generation in PJM remained between only 5% and 14% of total wind capacity during the hours of greatest customer demand, and never exceeded 33% of total wind capacity that day. At 11:00 am EDT on July 9, total wind generation in PJM actually went negative (to -8 MW), while the customer load in PJM at that time was 127,654 MW. One can only assume that at this point in time the aggregate “parasitic load” of wind units in PJM (the power needed to run the pitch and yaw mechanisms inside the turbine’s nacelle and other equipment on-site) exceeded any actual output by that amount.

Yet, sharp drops in aggregate wind generation in PJM are not limited to the summer. Although total wind output in PJM hit 4,403 MW on March 9 of this year (comprising 84% of total wind capacity in the RTO), the consistency with which aggregate wind output converged on zero this year, as shown in the table below, is remarkable. In addition, different days during the same month can produce widely disparate results, even at the same time of day, as seen in statistics for the month of February.

Advances in demand response and time-of-use pricing of electricity promise to reduce peak load in PJM in the coming years, but even quantum leaps forward in energy storage technologies can only do so much to even out the intermittent output from wind energy facilities in the region. Moreover, the evolving “smart grid” cannot compensate for wind energy’s abysmal performance during the dog days of summer. If we are committed to moving away from fossil fuels for the generation of electricity, we will simply have to find an alternative to onshore wind energy in central Appalachia to beat the heat.

Sources (last accessed August 31, 2012):

PJM Interconnection, eData guest function, https://edata.pjm.com/eData/index.html

PJM Interconnection, 2011 Regional Transmission Expansion Plan, (http://www.pjm.com/documents/reports/rtep-documents/~/media/documents/reports/2011-rtep/2011-rtep-book-1.ashx)

PJM Interconnection, “PJM Wind Power Statistics” (PowerPoint presentation) (http://www.pjm.com/~/media/committees-groups/task-forces/irtf/20120820/20120820-item-06-wind-report-july-2012.ashx)

PJM Interconnection, “Operations – 2012 Summer Conditions” (PowerPoint presentation), (http://www.pjm.com/~/media/committees-groups/committees/oc/20120710/20120710-item-04-pjm-operations-012-summer-conditions.ashx)

Note: Mr. Stephens is the acting Executive Director of the Allegheny Highlands Alliance. This article reflects his views, but not necessarily those of the organization.