POWER November 2014 - 31

HEAT RATE IMPROVEMENT
1. Big savings. Improving a plant's heat rate has the most direct effect on its bottom line.
The top chart shows savings at $1.50/MMBu; the bottom chart shows savings at $2.50/MMBtu.
Courtesy: EPRI
$5,000,000
$4,500,000
$4,000,000
$3,500,000
$3,000,000
$2,500,000
$2,000,000
$1,500,000
$1,000,000
$500,000
$0
$5,000,000
$4,500,000
$4,000,000
$3,500,000
$3,000,000
$2,500,000
$2,000,000
$1,500,000
$1,000,000
$500,000
$0
200
400
consumption of auxiliary power.
At the same time, in some areas, decreasing
coal quality and the use of higher-moisture-containing
fuels such as Powder River
Basin coal contributed to a reduction in unit
performance. A 2010 EPRI report, Evaluation
of Fuel Quality Impacts on Heat Rate
(EPRI document 1019703), has more on
the effects of fuel quality on heat rate. Most
recently, the proliferation of renewable and
natural gas generation, along with economic
factors, has resulted in a need for more flexible
operations (for example, more frequent
cycling and lower turndown) of the existing
coal-fired fleet, which has a substantial negative
effect on plant heat rate.
November 2014 | POWER
600
Net load (MW)
The problem of improving fossil plant heat
rates in the 1980s was made more difficult
by the penalties associated with retrofitting
emissions control equipment, declining coal
quality, and normal degradation associated
with aging of the units. This latter concern
continues today, as more units are operated
beyond their expected operating lifetimes,
with additional emission controls and increased
generation flexibility required.
The hurdles to improving performance were
further raised when many site performance
engineers were lost either to retirements or
shrinking personnel levels in the wake of the
deregulation movement of the 1990s.
Considering all these elements workwww.powermag.com
800
1000
200
400
600
Net
load (MW)
800
1000
ing against heat rate improvements in the
electric generation industry, it should not
be surprising that current industry estimates
suggest several percent of efficiency have
been lost at many existing coal-fired power
plants. However, a portion of that loss is potentially
recoverable if the correct processes,
procedures, and resources can be applied
and maintained.
The biggest hurdles are typically not technical,
they're financial. Limited budgets, concerns
about triggering New Source Reviews,
and the ability to pass along fuel costs through
adjustment clauses have been the biggest impediments
to heat rate improvements.
Assessing the Range and Applicability
of Heat Rate Improvements
Coal-fired power plants were initially designed
and built to achieve unit-specific heat
rates. The typical coal-fired plant is now about
30 to 40 years old and the operating heat rates
may be significantly different than initial design
values. Power plant owners and operators
are unsure of the range of possible heat rate
improvements for their existing fleets.
In recent years, several EPRI projects
have explored different aspects of heat rate
improvements. A recent EPRI report, Range
and Applicability of Heat Rate Improvements
(3002003457), summarizes the findings of
those projects to provide information on the
range and applicability of heat rate improvements.
This two-part series of articles is
based on that report.
Utilities have limited budgets and want to
know how much they can recoup or improve
by implementing actions and/or new technologies.
Because EPRI is looking at heat
rate from a holistic viewpoint, we were able
to evaluate projects at a plant level instead of
at a component level and have compiled an
extensive list of possible options.
Heat Rate Improvement-Capital
and Maintenance Projects
In 2008-2009, EPRI developed a methodology
to assess the costs and benefits of potential
maintenance improvements to coal-fired power
plants and refined the methodology to assess
the net annual benefit of potential capital
improvements to these plants. The assessment
methodologies were then applied to a hypothetical
500-MW plant to calculate the potential
benefits, including the heat rate reduction,
reduction in auxiliary load, capacity increase,
equivalent forced outage rate (EFOR) improvement,
and emissions reductions.
The calculations were captured in two
spreadsheets-one for capital projects and
the other for maintenance projects. Inputs
could be modified according to plant-specific
circumstances, thus making it possible for in31
Annual
savings
Annual savings
3% Heat rate improvement
2% Heat rate improvement
1% Heat rate improvement
1% Heat rate improvement
3% Heat rate improvement
2% Heat rate improvement

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POWER November 2014

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