POWER April 2017 - 48

OPERATIONS & MAINTENANCE
Strategies for Small
Hydro Upgrades
Source: U.S. Army Corps of Engineers
Small hydro is becoming big business as ongoing technological advances make
more small sites economic to exploit. Older plants can also see substantial output
and efficiency gains by upgrading from decades-old technology. Here's what you
need to know to help make small plants meaningful producers.
Thomas W. Overton, JD
S
mall hydropower is getting big.
Around the world, even as traditional
giant projects continue to get
built-especially in developing countries-
more and more attention is being directed
toward the possibilities of smaller systems.
The driving forces have been concern about
the environmental impacts of huge dams; a
shrinking number of suitable sites for major
projects, particularly in Europe and North
America; and substantial technological advances
that have made smaller and smaller
sites economic to exploit.
Hydropower in general is experiencing
something of a renaissance because of growing
demand for renewable energy. The rapid
growth of intermittent generation from wind
and solar means dispatchable renewable
generation from hydro is becoming more
valuable. But much of this wind and solar
development is taking place in areas-like
the central and southwestern U.S. and central
48
Europe-where opportunities for large hydro
projects are limited at best. That's opened
up a market opportunity for small systems
that can be deployed much more rapidly
than larger ones. (For more on the topic, see
" Small Hydro, Big Opportunity " in the May
2013 issue, " A New Day for North American
Hydropower? " in the October 2014 issue,
and " Small Hydropower Advances and Challenges
in China " in the January 2015 issue.)
New Tricks for Old Dogs
What exactly constitutes " small " hydropower
depends on who you ask, but it's generally
considered projects under 30 MW or so.
While lots of hydro projects of this size are
being built on new sites, not all small hydro
plants are new-many are quite old, with
some still operating after a century or more.
Many of these projects now need substantial
upgrades. The good news is that opportunities
for improving efficiency and output are
www.powermag.com
large (Figure 1).
According to Voith Hydro's Jim Glunt, the
last decade has seen significant advances in
controls, monitoring, and supervisory control
and data acquisition technology. Operators
are now better able to gather historical and
real-time data in order to maximize efficiency
or power on demand. Advances in operator
control and monitoring have also allowed
for more reliable and user-friendly interfaces.
Refurbishing old turbines can also reap
big rewards, Glunt said.
" Typically, a customer who is rebuilding a
50-year-old or older unit can expect around
10% improvement in efficiency. The wear on
the rotating components, wicket gate system,
and bearing areas can be corrected to add efficiency
and reliability, " he said. " Sometimes
in dealing with a unit rebuild of this age, there
can be misalignment throughout the machine
due to the tendency of the power house to
move downstream. The slow movement over
POWER | April 2017
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POWER April 2017

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