A powerful revival: Old dam in Pa. upgraded as
electricity source
Jun 15 - McClatchy-Tribune Regional News - Tom Pelton The Baltimore Sun
The century-old dam on the Susquehanna River doesn't look like an energy
source of the future.
Weeds sprout out of cracks in the weathered Holtwood Hydroelectric Dam, 12
miles upriver from Maryland. Inside the generating building, antique brass
volt meters look like something from Dr. Frankenstein's lab. Water snakes
slither across the floor.
Despite the decrepit appearance, a Pennsylvania power company is planning to
spend $350 million to build new water-powered turbines next to the dam. The
first new hydroelectric power plant in the East in 20 years, it would double
the dam's electrical output, providing another 100,000 homes in the region
with pollution-free electricity, according to the company.
At a time when utilities are looking to generate more power without
global-warming pollution, some point to the PPL Corp.'s Holtwood project as
a good example of going back to the future.
"Hydropower has been nearly forgotten, but it's a great source of
electricity because it's completely emission-free and combustion-free
generation," said Douglas Hall, manager of the water energy program at the
U.S. Department of Energy's Idaho National Laboratory.
Increasing the efficiency of old plants can create more juice to meet rising
demand, Hall and others say. Across the country, power companies are
upgrading generators in 23 dams in Idaho, Kentucky and California, among
other places.
Hydroelectric dams were the original source of electricity for many of
America's cities a century ago. As late as the 1940s, 40 percent of the
electricity in the U.S. was generated by water pushing wheels andspinning
turbines. But the technology was neglected for decades after World War II as
coal-burning plants took over the dominant role in generating America's
electricity.
America today gets 7 percent of its electricity from hydroelectric power,
and this could rise to perhaps 11 percent by simply adding more and better
generators to existing dams, Hall estimated. That would mean more clean
energy without blocking additional rivers or flooding more valleys -- major
environmental drawbacks that halted most major construction of dams in the
U.S. by the 1950s.
About 79,000 dams are scattered across the U.S., many dating to grain mills
of the 19th century. Only 2,400 of these dams have hydroelectric generators
built into them. Adding more turbines to the existing dams could add as much
as 37,000 megawatts of power, Hall said. That's enough electricity to light
up 27 million homes.
"There is growing interest in hydropower, because it is one of the potential
solutions to global warming," said Linda Church Ciocci, director of the
National Hydropower Association.
The addition of a second powerhouse at the Holtwood dam requires approval
from the Federal Energy Regulatory Commission and the Pennsylvania
Department of Environmental Protection, among other government agencies. If
the project is approved, construction could begin early next year and be
finished by 2011.
The proposal has drawn no major protests from environmental groups, although
American Rivers urged the FERC to consider the impact of blasting during
construction on wildlife in the area, according to agency records. But
officials with the U.S. Fish and Wildlife Service and the Maryland
Department of Natural Resources have suggested that improved flow through
the rebuilt dam might actually help migratory fish.
The Holtwood expansion would transplant a second heart into a workhorse that
has been clomping away steadily since before the Titanic was launched.
Construction on the Holtwood dam started in 1905 and finished in 1910. The
five-story-high wall of concrete stretches for nearly a half-mile across the
Susquehanna in a wooded valley.
The dam transformed the rocky, shallow river into a deep blue reservoir,
called Lake Aldred, which is eight miles long. It's the second of four
hydroelectric dams (after the Conowingo Dam in Maryland) that radically
transformed the Lower Susquehanna from a natural river into a stepped series
of artificial lakes.
Attached to the Holtwood dam is a rectangular building, 500 feet long, 100
feet wide and 150 feet tall, with ornate neoclassical decorations and rows
of grand arches. Inside hum 10 hydroelectric generators, each about 20 feet
in diameter.
About 240,000 gallons of water per second from the river rush through a
screen that catches floating sticks (and often water snakes). The current
pushes blades on wheels, making turbines spin. This generates 109 megawatts
of electricity, enough to light up about 90,000 homes.
Some of the machinery is so old that it has been designated an International
Historic Mechanical Engineering Landmark.
"The architecture is pretty amazing," said Chris Porse, manager of the
Holtwood dam. "The arches are reminiscent of Roman architecture. It's a
reminder that water power has been around for centuries, with the Egyptians,
Romans and Greeks all using it."
Next to this artifact, the company plans to dig 135 feet down into solid
rock. In this hole, the company proposes to build a second powerhouse. The
building would be smaller than the old one but would hold two new
hydroelectric generators twice as large as the 1910-era machines. The new
turbines could pump out 125 megawatts of power, more than doubling the dam's
current capacity.
"The new building will be built right here," Porse said, pointing to a blue
line that has been spray painted in a box shape on blacktop near the dam's
entrance. "For people in the hydroelectric industry, this is a
once-in-a-lifetime project."
Downstream from the dam, much of the Susquehanna River is a barren-looking
washboard of boulders, wetlands and scrubby trees. Beside this riverbed, a
narrow, fast-moving stream pours out of the dam's outfalls into a narrow,
stony valley. The current flows too fast for rare American shad to migrate
along this route upstream to spawning grounds.
The Holtwood project would attempt to address this problem by dynamiting and
excavating in a roughly mile-long section of the Susquehanna River to make
the channel wider, said Porse.
This would slow the current and help the passage of migrating fish. If they
can make it through a slower current, the shad could swim into a mechanical
fish lift built 10 years ago on the dam. The elevator hasn't been a success
because fish can't get to it, Porse said.
An environmental activist who has been studying the project, Michael
Helfrich, the Lower Susquehanna river keeper, said adding more turbines
could chop up more fish that pass through the dam. But he said adding more
hydroelectric generation is a good idea.
He noted that this section of the Susquehanna is already one of the most
generating-intensive areas of the world. Two nuclear plants (Three Mile
Island and Peach Bottom), four hydroelectric dams (including Maryland's
Conowingo), a coal-fired plant, a natural gas plant and a municipal
incinerator all line a 50-mile stretch of the river.
"I would rather see the hydros than any of the other power plants that are
up and down this river," Helfrich said. "Hydroelectric power isn't
impact-free, but it creates no greenhouse gases -- and I think it's better
than coal, natural gas or nuclear as a way to get electricity."
tom.pelton@baltsun.com |