POWER April 2016 - 48

OPERATIONS & MAINTENANCE
Weighing Costs and Benefits in
Hydropower Maintenance and
Upgrade Decisions
Courtesy: Creative Commons/Gregg M. Erickson
Choosing whether to maintain or upgrade hydropower plant components can be
difficult. Poor original equipment reliability can force changes, but often a detailed
cost-benefit analysis is needed to make decisions. Understanding how others have
tackled the process can help ensure success at your plant.
Aaron Larson
A
lthough other renewable sources of
energy may be growing at a faster
rate, more electricity continues to be
generated in the U.S. by conventional hydropower
than by wind, solar, and geothermal
power combined. A market report released
last year by the U.S. Department of Energy
Wind and Waterpower Technologies Office
noted that of the 2,198 active hydro plants
in the U.S., most of the 79.64 GW of total
installed capacity is located at large projects
built between 1930 and 1970.
A lot has changed since those plants began
generating power. Technology and design
techniques have evolved, allowing vast
improvements to all kinds of power plant
equipment. Digital governing systems now
offer plants programmable features, providing
flexibility and making what used to be
difficult changes simple. New runner designs
and insulation improvements have enhanced
48
efficiency and increased capacity. Composite
bearings have made maintenance easier and
less time consuming.
So the question many decision-makers
must answer is: " Should we continue to
maintain the old equipment in our relatively
reliable facilities or should we upgrade to
new equipment that captures the benefits offered
by the latest technology? "
Evaluating the Risk
Making that type of decision may seem pretty
straightforward, but Darin Johnson, president
of Seattle-based BIS Consulting, told POWER
that there is more to it than a person might
think. Determining if a new piece of equipment
that offers a 2% efficiency improvement
is a cost-effective upgrade can require the use
of heavy-duty dispatch models.
Another question that often arises is: " If a
unit is being taken out of service for an exwww.powermag.com
tended
period of time to complete one plant
improvement, does it make economic sense
to increase the scope and take care of other
upgrades at the same time? "
That's where a company like BIS Consulting
can help; it has been involved in several
hydropower assessments as part of life extension
programs. The company basically
applies a risk-based approach to estimate
the benefits of replacing or refurbishing old
components. It determines the likelihood of
component failure, the consequences if a failure
occurs, and then weighs the risk against
the incremental capital costs to conclude
whether an upgrade is justified.
" We're sort of doing the calculations that
everybody is thinking about, " Johnson said.
Most companies understand what the
tradeoffs are, but actually performing the
calculations explicitly and documenting all
of the assumptions requires more than just
POWER | April 2016
http://www.powermag.com
POWER April 2016

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