Environmental Engineering Reference
In-Depth Information
2
Impacts of I
ntermittent Generation
PorterBennett,JozefLieskovsky,andBranninMcBee
CONTENTS
Introduction ........................................................................................................... 17
Wind, Gas, and Coal Integration ........................................................................ 18
Impacts of Cycling ................................................................................................ 21
PSCO Case Studies................................................................................................ 29
Data and Methodologies ................................................................................. 29
July 2, 2008, Wind Event.................................................................................. 30
Ramp Rates for Selected PSCO Plants...................................................... 30
Calculating Emission Impacts ................................................................... 32
Conclusions Related to July 2, 2008, Wind Event ................................... 38
September 28-29, 2009, Wind Event .............................................................. 38
PSCO Case Study Conclusions....................................................................... 42
Comparison of PSCO and ERCOT Systems...................................................... 42
Wind, Coal, and Natural Gas Interactions in ERCOT System........................ 42
Frequency of Coal and Gas Cycling .............................................................. 43
Emission Impacts: J.T. Deeley Plant Case Study.......................................... 45
Conclusions Related to ERCOT Operations................................................. 47
General Conclusions and Future Outlook......................................................... 48
References............................................................................................................... 50
Introduction
Intermittent solar and wind energy sources stress the flexibility limits of
fossil fuel generation sources to the point where some exhibit severe inef-
ficiencies. Because the utilization of intermittent energy sources is generally
mandated by renewable portfolio standards (RPS), system operators must
dispatch fossil fuel units to meet total load net of renewable generation,
known as net load. Flexible generation sources such as stored energy and
natural gas power plants are able to balance the intermittent and volatile
generation outputs of wind and solar energy, in contrast to coal facilities that
are made more inefficient by irregular operation. When coal facilities are
