POWER May 2013 - 66

RENEWABLES
3. Wings on a conveyor belt. Water
conveyed through a pipe or penstock enters
the Schneider Linear hydroEngine and encounters
a cascade of fixed foils, which direct flow
into a cascade of moving blades. After passing
over the moving blades, the water flows
through a second cascade of guide vanes and
blades moving in the opposite direction. Courtesy:
Natel Energy
4. Power from low-head resource. Water is diverted to an intake conduit before it
passes through the turbine to generate electricity and is returned to the main channel. Source:
Natel Energy
Trash rack
Intake
Jib crane
Bypass flow
Draft tube
hydroelectric manager, pictured in Figure 2.
For example, environmental considerations
require that the adjacent Boulder Creek have
a minimum water flow equal to 4 cubic feet
per second. During periods of drought-such
as in 2002 as well as early this year-no water
is available for power generation as water
managers conserve resources in the city's
64-square-mile mountaintop watershed.
Irrigation and Other Supply Sources
Still smaller technologies are being developed
for use in low-head, high-flow situations that
exist in settings as diverse as irrigation canals
and drinking water distribution pipes.
For example, Alameda, Calif.-based Natel
Energy developed a fully flooded, two-stage
impulse turbine, called the Schneider Linear
hydroEngine or SLH, that resembles a
series of airplane wings on a conveyor belt
(Figure 3). The turbine's innovation is that it
is optimized around flow, not pressure, said
Gia Schneider, chairman and CEO. Water
conveyed through a pipe or penstock enters
the SLH and encounters a cascade of fixed
foils, called guide vanes. These guide vanes
direct flow into the first cascade of moving
blades. After passing over the moving blades,
the water flows through a second cascade of
guide vanes and then passes through a second
cascade of blades moving in the opposite
direction. The guide vanes are adjustable in
pitch, allowing for direct control of flow rate,
66
thus keeping the machine's efficiency high
across a range of flows.
The company has a 50-kW, 4-foot-tall unit
on the market, as well as a 0.5-MW, 8-foottall
unit. Development is under way on a unit
with a capacity between 1 and 10 MW that
is expected to be available in 2015. In 2009,
the company installed a small unit on a canal
owned by the Buckeye Water Conservation
and Drainage District in Arizona. That project
had 6 feet of head, produced 8 kW, and
is grid connected. The generating system's
general design is shown in Figure 4.
A second small-scale technology was developed
by Lucent Energy for use inside water
distribution pipes. It uses a vertical-axis turbine
similar to a wind turbine with the shaft
perpendicular to the water flow. The turbine's
design ensures that downstream pressures are
maintained. The turbine allows the water to go
through it, but at the same time, because of the
geometry of the blades, it's able to turn and lift
like an airplane wing and turn a generator. A
prototype 20-kW system was installed in early
2012 in a water distribution pipe in Riverside,
Calif. A second, four-unit, 200-kW system is
being installed in a 42-inch-diameter water
pipe in Portland, Ore.
" The shaft can go through the pipe wall
without being exposed to water in the pipe, "
said Josh Thomas, engineering program
manager. The components are all certified for
use in drinking water supplies, but Lucent is
mindful of water quality issues such as sediment
and alkalinity that can adversely affect
its equipment.
Two years ago during the economic slowdown
and collapse of the price of natural gas
in the U.S., Hydro Green Energy, a smallscale
hydropower developer, turned its focus
toward Latin America, in particular Chile,
www.powermag.com
Colombia, and Panama. Efforts are under
way in those markets to shift from fossil fuels
for generation to renewable resources such as
hydro, said Michael P. Maley, president and
CEO. In the U.S., the company has more
than two dozen preliminary licenses to install
up to 340 MW of generating capacity in 13
states. But the company views the licensing
and approval process as inefficient and slow,
with little urgency on the part of the Corps of
Engineers or the Bureau of Reclamation to
evaluate small-scale projects and coordinate
efforts with FERC.
In the case of Hydro Green Energy, the focus
is on modular design using off-the-shelf
equipment that can be readily installed at an
existing structure. Both the turbine and the
generator are in frames that can be easily removed
for maintenance and are designed to
run for 75 years, said Maley.
Ready for a Renaissance
To better enable Hydro Green Energy's
installation of technology with a 75-year
lifespan, the NHA and its member companies
have to get the Senate to approve the
small-hydro bill that won unanimous House
support in February. Once that happens, the
NHA's Jeff Leahy said a " renaissance " in
U.S. hydro development could take place.
That's something of a loaded term in the
power generation industry, which heard
promises in recent years of a nuclear renaissance
that failed to materialize. But hydro's
fortunes may be different, buoyed by comparatively
simple technology, readily adaptable
existing infrastructure, and an abundant
and renewable fuel source whose value as a
tool has withstood the test of time. ■
-David Wagman is executive editor
of POWER.
POWER | May 2013

http://www.powermag.com

POWER May 2013

Table of Contents for the Digital Edition of POWER May 2013