Business Energy Editor's Blog
Friday, June 14, 2013 5:17 PM
NREL Puts a New Spin on Utility Claims for Spinning Reserve
The utility industry has a history of publicizing solar and wind intermittency as being detrimental and costly to spinning reserve equipment. But new research from the US National Renewable Energy Laboratory (NREL) tells a different story. Moreover, it echoes information given 6 years ago, by Karl Pfirrmann, Interim President and CEO of PJM Interconnection.
In 2007, Citizens for Pennsylvania’s Future interviewed Pfirrmann on the subject of wind intermittency. PJM is the world’s largest grid operator, and responsible for keeping a network of public and private utilities running smoothly across 14 states in the northeaster and southern US. Pfirrmann noted that wind did not pose significant costs as a result of its variable nature because the transmission system is sufficiently flexible and can readily accommodate changes in power flows. As to the impact on spinning reserves (standby generators) to mitigate intermittency, Pfirrmann said that costs were modest and deducted from payments wind generators received for energy deliveries. So even then, renewables paid for any impact to spinning reserve equipment. Moreover, he observed that most generators are sufficiently flexible and can be backed down with minimal effects on their operating efficiency.
Confirmation of Pfirrmanns’s observations were just published by the U.S. National Renewable Energy Laboratory in a two-phase project, “The Western Wind and Solar Integration Study (WWSIS)”, one of the largest regional wind and solar integration studies to date. Phase 1, published in 2010, analyzed the operational impacts of high penetrations of wind and solar power on the Western Interconnection power system of the United States. It found “no technical barriers to the integration of high penetrations of wind and solar power (up to 35%), if certain operational changes could be made. The two most important changes are increased balancing authority coordination and sub hourly scheduling between balancing authority areas.”
In 2012, NREL completed Phase 2 (WWSIS-2) after examining new data and address utility concerns about damage to fossil-fueled generators as they vary their output to manage intermittency from renewables. This was in response to the claim from utilities that heat rates and emissions from fossil-fueled generators could be higher during cycling than during steady-state operation. At the time of Phase 1, there was little available information on wear-and-tear costs because this information was considered proprietary by plant owners. For Phase 2, researchers worked with industry partners to analyze data collected from cost studies on 400 fossil-fueled plants over several decades. The simulations and analysis conducted for WWSIS-2 determined that “the impacts of wind-induced cycling are minimal and capped the wear-and-tear costs at 2% of the value of wind and the emissions impacts at +/- 3%. Although there are wear-and-tear and emissions impacts from generator cycling, these are modest compared to the overall benefits of replacing fossil-fueled generation with variable renewable generation.”
So, according to the latest findings from the NREL, it’s a case of strong evidence of weak consequences. But according to Ken Skylar, manager of renewable services at PJM, there is an issue facing distributed renewables. But it relates to the design and age the transmission infrastructure of the grid. “Upgrades are needed to the distribution system because it wasn't designed to accommodate large amounts of variable frequency resources on these individual feeders,” Skylar explains. “There could be significant changes in voltage on a feeder and reverse power flows on the lines if a system isn't designed to handle that. A lot of the PJM members that own distribution systems have indicated that it's a big concern for them.”
Ultimately those upgrades would occur as utilities adopt smart grid technology, and smart grid technology offers a good return on investment to utilities, and government programs that help fund the upgrades. For example, a recent study by the US Department of Energy (DOE), “Economic Impact of Recovery Act Investment in the Smart Grid,” found that smart grid projects funded through the American Recovery and Reinvestment Act (ARRA) resulted in roughly $7 billion total economic output, 50,000 jobs, and a return of $1 billion in government tax revenue. The study reviewed $1.48 billion in ARRA investments from the Smart Grid Investment Grants and Smart Grid Demonstration Program programs, plus $1.48 billion in matching investments from grant recipients in the private sector between August 2009 and March 2012. In short, $3 billion in smart grid project funding returned $6.83 billion in total economic output.
Now, that’s some news that needs no spin.