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Hastening Genco Obsolescence?

DER: This final installment of Oak Ridge National Laboratory's series on distributed energy resources investigates efficiency, the environment, and generation displacement.

Fortnightly Magazine - May 2005

only electricity) would increase by 3.1 TBtu. However, if thermal energy use is included, then the net total fuel used declines by 4.2 TBtu.

Moreover, in all cases, with DER providing only electricity, the fuel use and consequent CO 2 emissions from the DER were greater than from the displaced central generation, so there was a net increase. However, both the total emissions rate from the DER and the net system increase in emissions are less than the RAP model emissions rule for 2012. 4 Even better, when CHP was included in the model, the net fuel use and CO 2 releases were less than from the combined displaced electric generation and thermal energy production. Except for the scenario involving canceling 2,000 MW of CC with weekday-only DER operation, all scenarios had reductions in NO X emissions even without the use of CHP. It could be argued that the most likely scenario is a combination of the bounding extreme cases considered here. That is, some plants will be retired, some new plants will be deferred, and other capacity plans will be unaffected. So although the scenarios are not equally likely, the average results of all the scenarios are informative. Without CHP, net fuel use and CO 2 emissions increased by roughly 250 lbs/MWh of DER generation, but net NO X emissions declined. For every megawatt-hour generated by DER, total NO X emissions from all sources declined by about 1 pound, which is significant when considered relative to the RAP model emissions rule limit of 0.15 lbs/MWh in 2012. When CHP is included, the energy use, CO 2 emissions, and NO X emissions all declined significantly, with net NO X emissions declining by around 4 pounds for every megawatt-hour generated by DER.

Improvements in energy and emissions were significant across the broad range of scenarios. Even when new gas-fired CC capacity was canceled in proportion to the impact of DER on system loads, net NO X emissions were reduced. Utilizing the exhaust heat from the DER compounded the savings and made DER with CHP a valuable component of the country's energy portfolio, reducing both total fuel use and emissions.


  1. EIA 2004, Short-Term Energy Outlook , U.S. Department of Energy, Washington, DC, June..
  2. Iannucci, Joe, Susan Horgan, James Eyer, Lloyd Cibulka, May 2002, Analysis of  NOx Emissions Limits for Distributed Generation in Texas , Distributed Utility Associates, Livermore, CA.
  3. EIA 2003, The Assumptions to the Annual Energy Outlook 2003 , DOE/EIA-0554(2003), U.S. Department of Energy, Washington, D.C., January.
  4. Issues Letter, July 2003, Regulatory Assistance Project, 177 Water Street, Gardiner ME,