Environmental Engineering Reference
In-Depth Information
high costs.* This is especially true for baseload power plants that were not
designed to cycle. While it is hard to quantify exactly the costs arising from
cycling damage, it is important to include them when projecting wind inte-
gration costs. To date, however, most wind integration studies (including
those of PSCO) have ignored such costs.
5
For power plants designed to operate at steady baseload, cycling due to the
wind is like driving a car calibrated for the plains of Nebraska in the moun-
tains of Colorado. Such plants will burn more fuel and cause higher emis-
sions. Their operations will cost more over the long run when maintenance
and shorter life spans are considered.
PSCOCaseStudies
The previous section explained in theory how cycling coal-fired generation
plants causes them to operate inefficiently, raising their heat rates and creating
a host of other deleterious impacts. This section takes the analysis further by
examining two wind events described in detail by PSCO in training materials.
Data and Methodologies
The data employed in these analyses are critical to their credibility. The
emission data for CO
2
, SO
2
,
and NO
X
derive from the CEMS database main-
tained by the United States Environmental Protection Agency (EPA). Electric
utilities are required to report hourly their total generation, CO
2
, SO
2
,
and
NO
X
emissions by boiler by plant for all boilers over 25-MW nameplate
capacity. Total load is based on data reported by PSCO to the Federal Energy
Regulatory Commission (FERC) on Form 714. All control area utilities are
required to submit hourly load data.
For any given utility territory, total load data, as reported on Form 714,
equals the sum of generation from all plants reported in the CEMS data
plus generation from nuclear, wind, hydroelectric, solar, and other non-coal,
gas- or oil-generated purchases (spot and contract) from other utilities.
Separating wind and hydroelectric generation on an hourly basis is not pos-
sible for PSCO's territory because PSCO is not required to report wind gen-
eration beyond monthly and annual levels. As noted in an earlier footnote,
PSCO denied requests for 2008 hourly wind generation data and contends
that the data represent confidential trading information. Nevertheless, PSCO
published hourly data from two dates for studies and training manuals. The
*
While most plant components are designed to handle cycling, generation changes directly
impact water systems, pulverizers, boilers, scrubbers, heat exchangers, and generators.
Catastrophic failures resulting from excessive cycling arise commonly from fatigue, corro-
sion, and cycling-related creep. Such failures may eventually cause plant shutdowns and
large capital expenditures for replacement of damaged equipment.
