POWER May 2013 - 64

RENEWABLES
nation's 80,000 or so dams have electricity
generation associated with them. Oak Ridge
National Laboratory (ORNL) published in
April 2012 a study of hydropower potential
in the U.S. It found that many of the monetary
costs and environmental impacts of dam construction
have already been incurred at these
non-powered dams (NPDs), so adding power
to the existing structure often can be achieved
at lower cost, with less risk, and within a shorter
timeframe than through new dam construction.
The abundance, cost, and environmental benefits
of NPDs, combined with the reliability and
predictability of hydropower, make these dams
a potentially attractive way to expand the nation's
renewable energy supply.
Of the more than 80,000 NPDs throughout
the U.S., 54,391 dams were analyzed by
ORNL, with the remainder eliminated from
consideration due to faulty geographic information
or erroneous flow or drainage area
attributes. ORNL said that adding power
generation to U.S. NPDs has the potential
to contribute up to 12 GW of new renewable
capacity-a potential that it said is equal to
increasing the size of the existing conventional
hydropower fleet by 15%. Most of
this potential lies in just 100 NPDs, which
could contribute some 8 GW of hydropower;
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ORNL said the top 10 facilities alone could
add up to 3 GW of new hydropower.
The ORNL study also found that 81 of the
100 top NPDs are U.S. Army Corps of Engineers
facilities, many of which, including
all of the top 10, are navigation locks on the
Ohio, Mississippi, Alabama, and Arkansas
Rivers, and their major tributaries. The study
also suggested that dams owned by the Bureau
of Reclamation hold the potential to add
another 260 MW of capacity.
Three different small-scale hydropower
ventures illustrate the range of projects and
technologies that could be deployed across the
U.S. One is a series of hydropower installations
at Corps of Engineers navigation dams.
The second is a repowering of a powerhouse
in the Rocky Mountains with a high head. The
third represents two new technologies that
could expand the distributed nature of smallscale
power in water supply systems.
Power from the Ohio River
American Municipal Power-Ohio (AMP) is
building five new hydroelectric projects on
Corps of Engineers dams along the Ohio River.
Altogether, the projects will add more than
350 MW of hydro generation to the region.
Voith Hydro is manufacturing the turbines and
generators for the first four projects, which include
run-of-river generating facilities. Nearly
80 AMP member communities are participating
in the projects, all of which consist of an
intake approach channel, a reinforced concrete
powerhouse, and a tailrace channel.
These projects are among the first to be developed
on Corps structures in decades, and AMP
had to be patient and persistent to win both a
FERC license and Corps approval. The process
was " a bit painful " but opened the Corps' eyes
to how the approval process might be streamlined,
said Paul Blaszczyk, a vice president and
the project manager for MWH, the consulting
firm serving as AMP's engineer for all of the
projects. As a nonprofit, AMP was able to secure
good interest rates for the projects. What's
more, it considers the projects to be 100-year investments,
a point of view that helped improve
the projects' economics and keep the lengthy
approval process in perspective.
AMP's Cannelton Project will divert water
from the existing Corps Cannelton Locks and
Dam through bulb turbines to generate an average
gross annual output of roughly 458 GWh.
The " bulb " designation comes from the shape
of the upstream watertight casing, which contains
a generator located on the horizontal axis.
The powerhouse will house three horizontal
Common
Hydroelectric Terms
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Cavitation: Rapid changes in pressure
result in the formation of bubbles that
then collapse when the water passes
into higher-pressure regions of a turbine.
Repeated cavitation can damage
turbine blades.
Flow: The volume of water passing a
point in a given period of time.
Head: Vertical change in elevation between
the head water level and the tailwater
level.
Headwater: The water level above the
center line of the turbine.
Low head: A head of 66 feet or less.
Penstock: A closed and pressurized conduit
or pipe for conducting water to the
powerhouse.
Runner: The rotating part of the turbine
that converts the energy of falling water
into mechanical energy.
Tailrace: The channel that carries water
away from a dam.
Tailwater: The water downstream of the
powerhouse.
Ultra-low head: A head of 10 feet or less.
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POWER May 2013

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