By Steve Blankinship, Associate Editor
As one of the earliest and most elementary forms of power generation, hydropower remains by far the largest source of renewable energy in the world, including in North America.
In the early 1900s, hydropower was the dominant source of U.S. electric generation and as recently as the 1940s accounted for more than 40 percent of electricity production. By the 1950s, developers had tapped the hydro potential of the most mountainous regions in the U.S. –many in the Northwest–where steep inclines supply the strongest river flows and permit the most cost-efficient projects.
 Three percent of U.S. dams are equipped to produce power and annually generate 270,000 GWh. |
Hydropower supplies almost two-thirds of Canada’s power and makes it the world’s largest hydropower producer, representing 13 percent of global output. It’s also the world’s second largest exporter of hydro (after France). Altogether, its roughly 450 hydro plants, half of which produce less than 10 MW, account for 72,660 MW with another 1,800 MW currently under construction and an additional 12,000 MW under consideration, according to the Canadian Hydropower Association.
Today, hydro represents about 8 percent of all power in the U.S. and more than 90 of all the renewable power generated in the nation. Hydro provides more than 16 times as much energy as wind and solar power combined.
And hydro’s use is increasing, both through updates to older hydro generation technology and through new technologies. Utilities are proposing more than 70 projects that would boost U.S. hydroelectric capacity by at least 11,000 MW over the next decade.
Driving a new wave of hydropower development is unprecedented demand for renewable energy and rising fossil fuel costs. The American Recovery and Reinvestment Act and other programs provide tax provisions to attract investment in incremental hydropower, hydro at non-powered dams, ocean, tidal and in-stream hydrokinetic technologies.
Upgrades and New Builds
AMP-Ohio, which owns and operates power production facilities for 126 member entities in Ohio, Pennsylvania, Michigan, Virginia, West Virginia and Kentucky, is developing multiple hydroelectric projects, representing one of the largest deployments of hydroelectric generation in the U.S. The projects are run-of-the-river hydroelectric facilities to be installed on existing dams on the Ohio River and the New River in West Virginia. Combined, these six projects would add more than 380 MW of new generation at an estimated construction cost of just over $1.5 billion.
As part of the project, AMP-Ohio signed a contract worth more than $300 million with Voith Siemens to manufacture turbines and generators for the first three of these projects at the Smithland, Cannelton and Willow Island locks and dams. A fourth Ohio River project will be at the Meldahl locks and dam. In addition, AMP-Ohio is pursuing a project at the R.C. Byrd locks and dam on the Ohio River and performing a feasibility study for a project at the Bluestone dam on the New River.
PPL Corp. recently filed a request with the Federal Energy Regulatory Commission for a 125 MW expansion at its Holtwood hydroelectric plant on the Susquehanna River in Pennsylvania. Holtwood currently is rated at 108 MW and has generated power since 1910. The estimated $440 million project is subject to availability of stimulus funding. Construction could start early next year.
“The hydro business is so robust right now that the contractors only go after big projects, leaving lots of room for smaller players to stay busy with medium and smaller projects,” said Norm Bishop, vice president for the hydro dams market sector of MWH, a Colorado-based firm that helps develop new hydro projects and update existing ones.
In addition to the demand for renewables and the rising costs of fossil fuels, Bishop cites hydro’s flexibility that allows it to meet today’s power market demands, including ancillary grid support, which is especially critical in places with increasingly high penetrations of wind farms.
And the potential to make cheap power from water has barely been tapped. Of the existing dams in the U.S., 3 percent (or around 2,400) are equipped to produce power and annually generate 270,000 GWh, according to the U.S. Department of Energy. DOE estimates another 30,000 MW of capacity could be developed, including 17,000 MW at existing dams.
Pump It Up
After decades of little or no development, U.S. hydro pumped storage (by which water is pumped uphill during off peak demand periods and released to flow down hill to spin generating turbines on peak) is seeing renewed attention. In the past two years, FERC has approved 21 preliminary permits for pumped-storage projects totaling more than 12,000 MW.
Earlier this year, Energy Secretary Steven Chu said hydro pumped storage must be a part of a national plan to expand clean-energy resources and integrate variable renewable energy resources into the transmission grid. Chu said the U.S. has limited existing resources for storing energy and most of what it does have comes from the 20,355 MW of pumped-storage capacity now in service.
National Hydropower Association (NHA) Executive Director Linda Church-Ciocci said that expanding hydro pumped storage capacity will be a high priority for her association’s new pumped storage council.
“Right now, the federal government has no program to spur expansion of U.S. pumped storage,” she said. “We advocate investment tax credits or other similar measures that can incentivize pumped storage development immediately.”
A benefit could be changes to the licensing process, an initiative NHA has worked on for a number of years. The new process focuses on collaboration among agencies, which should reduce the amount of time required for a new or renewed license from 15 years to as little as three or four years.
Relicensing is hot right now as owners hope to eke even 2 or 3 percent improvements for a price tag that can be as low as $200/kW in some cases.
“There’s a tremendous opportunity to repower and upgrade the mechanical aspects of existing facilities to increase output,” said Don Erpenbeck, another MWH vice president. He’s particularly upbeat with some new technologies that include ultra low head hydro and emerging technologies such as hydrokinetic.
“If a project is 20 years old there’s a good chance today’s technology can eke out more power at a very small cost per kW.”
Water to Wire = Ultimate Efficiency
Hydro power has always had high availability and quick ramp rates. It also enjoys an overall efficiency unmatched by any other power source. No fuel is needed, just the volume and motion of the water. Mechanical efficiency is high and the only true efficiency losses are limited to line loss.
“Availability is pushing 90 percent with hydro and on the mechanical side we hit 95 percent efficiency,” said Erpenbeck. But some plants have lost as much as 10 percent of their efficiency due to the age of their turbine/generators. New technology can not only reclaim that efficiency, but increase output above previous levels.
 Hoover Dam looms behind its switchyard and powerhouse deep in the Colorado River canyon that separates Nevada and Arizona. |
“You could be looking at up to 20 percent efficiency increases if the existing machines are in bad shape,” he said.
Hydro’s ability to ramp quickly enhances its attractiveness as a power portfolio asset. New technology can expand that flexibility. “We can make the efficiency curve flatter,” said Erpenbeck, “so hydro is more efficient running off peak. We can now run with even greater flexibility and respond to market conditions across a wider range of megawatts in terms of cycling, load following and turn down.”
Erpenbeck said hydropower can routinely operate at 55 to 100 percent of rated load and back off to 20 to 40 percent as needed.
Increases to operating range provide prime quality spinning reserve for grid support, which is more important today than ever before. The increases are achieved through the ability to run in condensing mode where the generator is synchronized and motoring while the turbine spins air, or synchronized at low power (20 to 40 percent of rated load) going to full power in seconds. “With all the wind power coming onto the grid this is being used much more,” said Bishop. “Modern hydro’s ramp rate is fast.”
Hydro also provides high-quality ancillary grid support. For example, Grand Coulee Dam on the Columbia River in Washington State can go from low load to full load (about 800 MW ) in matter of seconds.
Technology Improvements
Improvements to conventional hydro technology provide a variety of upgrades that help hydropower remain low cost while offering environmental benefits.
Grant County Public Utility District, part of the Mid-Columbia System, is installing 10, $15 million fish-friendly turbines at Wanapum Dam and plans to replace another 10 turbines at Priest Rapids. The old turbines are being replaced with models that use six smaller blades instead of five. When completed in 2012, the project is expected to improve each turbines’ efficiency by 3 percent and the facility’s overall capacity by 15 percent.
Recent upgrades to the Sacramento Municipal Utility District’s Jaybird and Loon Lake hydroelectric powerhouses have led to still more efficiency gains. Installing new computerized controllers to better regulate water flow to the turbines has increased output by 15 MW for the same amount of water when running at low power levels. The new governor control system automatically regulates the amount of water that shoots out of six high-pressure nozzles and onto a wheel that spins the generator.
With the old equipment, the controller opened all six needles at once, boosting water flow to the turbine as electricity demand rose. When the unit was at low load, it required less water. But this fanned out of the needles similar to a garden hose set to a wide spray pattern and caused most of the water to miss the turbine wheel.
The new equipment opens two needles initially and adds others as demand for power rises. By moving the same volume of water through two needles instead of six, the water stream is more tightly focused and hits the turbine wheel more directly. This results in significant water savings for the same amount of power generation. Based on current short-term power price forecasts, the utility estimates the equipment will save it $130,000 a year.
Canada’s two largest hydro utilities—Ontario Hydro and Hydro Quebec—continue to expand capacity. Hydro Quebec will announce this summer a revised hydro expansion schedule. But current expansion plans include completing the last generating units at the Péribonka development and the first units at Chute-Allard and Rapides-des-Coeurs.
Work also proceeded at the Eastmain-1-A/Sarcelle/Rupert jobsite. The project will divert a portion of the flow from the Rupert River watershed into the Eastmain River watershed. That will involve four dams, a spillway on the Rupert River, 74 dikes, two diversion bays, construction of a 1.8-mile-long tunnel and a network of canals and hydraulic structures on the Rupert River to maintain post-diversion water levels along half of the river’s length.
Ontario Hydro’s Niagara tunnel project will increase the amount of water flowing to turbines at the Sir Adam Beck generating stations at Niagara Falls, allowing them to better use available water. Upon completion of the 6.5-mile-long tunnel, average annual generation from the Beck stations is expected to increase by about 1.6 TWh. Ontario Power also recently completed a 12.5 MW hydroelectric generating station on the English River. The new Lac Seul generating station uses most of the spill currently passing the existing Ear Falls generating station, thus increasing overall efficiency, capacity and energy generated from the plant. The project is expected to be in-service later this year.
Ontario Power is proceeding with the definition phase for a 450 MW development on the Lower Mattagami River, including replacing the Smoky Falls station and expanding the Little Long, Harmon and Kipling stations. The company also approved redeveloping four existing stations, which otherwise would have been removed from service.
New Wave for Hydropower
The tremendous force of moving water is obvious to anyone who has stood in breaking ocean waves or swum against a river’s current. Hydrokinetic—or kinetic hydro—technologies generate electricity from waves or directly from the flow of water in ocean currents, tides or inland waterways and is gaining increased attention.
Hydrokinetic technology uses stream flow to make power and requires a steady three to five knots of flow to operate. Hydrokenetic water turbines (HUTs) can be placed where there is no dam; for example, they may be attached to bridges or to frames on the river bottom. Hydrokinetic boosts potential capacity far beyond conventional hydro power. As one example, thousands of miles of canals in California are designed primarily for irrigation, but could also host kinetic turbines.
HUTs are smaller than wind turbines because water is about 800 times denser than air. Ocean tidal current can deliver predictable 20 hours per day energy and a HUT can produce up to four times more energy than a wind turbine on a good day. Venturi and centrifugal designs can accelerate water speed through the turbine and double the energy produced. Current project proposals suggest that kinetic hydro produced by U.S. waves, tides and rivers, could produce 13,000 MW by 2025.
FERC has approved the nation’s first commercially-operational hydrokinetic power station in Hastings, Minn. The 4.4 MW run-of-river hydropower plant will use two hydrokinetic units, each with a nameplate capacity of 100 kW.
Near- and off-shore ocean waves might have the greatest hydrokinetic potential. Extracting just 15 percent of the energy in U.S. coastal waves would generate as much electricity as is currently produced at conventional hydro dams. Much of this wave potential is along the Pacific Coast and close to population centers.
Beyond the sheer size of the resource, hydrokinetics are attractive for their predictability. Wave patterns can be predicted days in advance. Since the kinetic energy held in a stream is related to its speed cubed, extracting the most electricity from each hydrokinetic project will depend heavily on site selection. Energy output increases eight times with only twice as much water current speed.
State and federal policymakers across the U.S. have taken notice of the potential of hydrokinetic energy and have begun to support its development through legislative and monetary means. Ocean energy is eligible for credit under renewable electricity standards in 16 states and for federal renewable production tax credits, as expanded in the Energy Policy Act of 2005. Furthermore, hydrokinetic energy development was marked for increased research funding appropriations in the 2007 Energy Independence and Security Act.
Overcoming Environmental Opposition
Hydro has all but disappeared from the renewable energy options usually cited by renewable energy advocates. Many environmentalists have long opposed hydroelectric power and do not consider it “green” or renewable. Much of the opposition is based on the water diversions required by traditional hydroelectric projects and the effects on land and wildlife. Fish killed as a result of passing hydro turbines has also led to a substantial amount of environmental concern.
Because of this environmental opposition, some states restrict the extent to which hydroelectric projects may qualify under renewable portfolio standards.
“Policy makers at the federal and state level have a difficult task of designing regulations and incentives that recognize the fact that an existing renewable source like hydropower can be further developed with the right incentives,” said Michael Cutter, vice president of engineering and development for Brookfield Renewable Power (BRP). The company has developed, owned and operated hydro power facilities for more than 100 years and has 100 hydropower facilities totaling nearly 2,000 MW in nine U.S. states.
Cutter said opportunities exist throughout the U.S. for continued development of hydro electric generation. “Recent studies show the amount of hydropower could double from the current amount of installed hydro generating capacity by 2030 if the country could upgrade existing hydropower, add hydropower at non power dams and develop some of the new technologies,” he said. “To reach hydropower’s potential it is important to continue to strengthen federal and state energy policies and educate the public on hydropower’s role as an indigenous, renewable energy source.”