Damless Hydro Power
By: Marc Hequet
What hangs under a barge and powers 150 homes? Hastings, Minn., will find out. Houston hydro developer Hydro Green Energy LLC is testing its new hydroelectric technology at Hastings (pop. 21,000) in the tail race of the U.S. Army Corps of Engineers dam where the city operates a four-megawatt hydro plant. U.S. hydroelectric power remains firmly dam-based, with the Tennessee Valley and the Northwest key regions — but other areas now also draw attention, and not just for dams.
Piggybacking on a dam’s existing license, Hastings’ would be the first dam-free generator feeding the grid. Its 200 kilowatts will be scarcely a spark compared with big base-load plants — but every megawatt can power 750 homes, and dam-free has its believers. Hydro Green raised $2.6 million from investors in April. Moreover, hydro fits the U.S. energy ideal. “We’re all looking for ways of producing clean energy and energy independence and controlling costs,” notes Linda Church Ciocci, the National Hydro Association executive director. U.S. hydroelectric capacity is 97,000 megawatts, about 9 percent of U.S. generating capacity. Natural gas, coal and nuclear account for 82 percent of nameplate. Still, hydro is the top renewable resource used for electric generation and its are prospects significant: A 2007 Electric Power Research Institute study estimates a potential for adding another 23,000 megawatts of hydro in the United States by 2025, including 10,000 megawatts from ocean waves and 3,000 megawatts from new Hastings-like technologies.
Dam-based and dam-free hydro are essentially the same — water turns a turbine to generate electricity. The differences are noteworthy: Dams create “head” — a drop through which water falls to generate more power. During high or low water, however, dam-based hydro may operate less efficiently or shut down. Dam-free’s advantage is, well, it doesn’t require a dam. Hydro Green’s enclosed, horizontal-axis barge-mounted units with rotors 12 feet in diameter needs 22 feet of stream depth. Another plus: If it doesn’t work, yank it out. Hydro Green plans barge-mounted units with collapsible gantries that can lift turbines out of the river for routine maintenance or outright removal. In theory, dam-free turbines work wherever current flows — and work best in deep and fast water. Turbines mounted on barges or pylons may power a few hundred households. Remote communities, take note: On Alaska’s Yukon River, costly diesel fuel runs local generators. Hydro Green has federal permits to study nine Alaskan sites. The firm might test smaller units in 2009, but its focus now is getting Hastings going.
One of the issues is whether turbines harm migrating salmon and other fish. Dam-free hydro developers say the turbines turn slowly enough to allow fish to escape. Hydro Green’s 15 preliminary permits also include two on the lower Mississippi. A rival, Free Flow Power Corp. of Gloucester, Mass., is more ambitious still: It has permits to study 55 sites on the Mississippi River, from St. Louis downstream. Brookfield Renewable Power Inc. of Gatineau, Quebec, plans up to 265 megawatts at existing Mississippi dams from Dubuque, Iowa, to St. Louis. Brookfield owns the biggest generator on the Mississippi River, Louisiana Hydro at New Orleans, rated at 192 megawatts.
Dam by dam down the Mississippi, however, what works requires study. “Each lock and dam has its own set of characteristics that can be very much favorable to hydro or very much unfavorable to hydro,” said Jeffrey Auser, Brookfield’s vice president for U.S. business development. Some cities want to develop hydro on their own. Quincy, Ill., has permits for three generators on the Mississippi. The cost is steep—$200 million. Quincy (population 41,000), with an operating budget of $30 million, has already spent $1.4 million. Yet Mayor John Spring says his City Council is all for it. With the three projects, Quincy hopes to have 52 megawatts of hydroelectric generating capacity by 2016.
Spring advises other cities interested in hydro to “take it one step at a time.” “We have to look at renewable energy. We know that this is something that can benefit not just the present generation, but this is for generations to come. I think it’s the future.” Yet LeClaire, Iowa, gave up on hydro after trying since 1979. A federal Fish and Wildlife Service requirement for a 1,400 foot “fish rack” barrier killed the project. The rack bumped costs 57 percent to $110 million. Still, LeClaire City Administrator Edwin Choate advises river cities to proceed if they think they can make hydro work. Dams elsewhere still count. Both the Tennessee Valley Authority and the Bonneville Power Administration are upgrading existing projects. TVA expects to add 526 megawatts of new hydroelectric generating capacity by 2016—10 percent of its existing capacity—without adding a dam.
California is evaluating five new surface storage projects for water management and hydro generators will likely be part of two of the projects. At one of the projects, new hydro generators will mitigate for a loss of 518 gigawatt-hours of energy per year that would be lost due to inundation of existing upstream power plants “We’re already hurting for power in California,” said Don Rasmussen, a supervising engineer with the California Department of Water Resources. Construction may start by 2012 and be complete by 2019. In Minnesota, Hastings’ 1980s-vintage hydro plant underperformed in high and low water until a 2001 flood. The city redesigned the damaged unit, including putting a trash rack in place to catch trees and other debris booming downstream. The plant has performed better since. “There’s been a big learning curve,” said Mayor Paul Hicks.
The Hastings plant now generates $1 million in annual revenue that Hastings sells to regional utility Xcel Energy — enough to pay the 30-year bonds city issued to build and fix it — “but we had a number of years when it didn’t,” Hicks said. “Costs related to licensing can be prohibitive,” said the National Hydropower Association’s Jeff Leahey. Even with existing dams, developers need federal and state approvals. They must work with interest groups, showing that their technology won’t interfere with navigation or harm fish. The same challenges apply to new-technology developers of what the Federal Energy Regulatory Commission (FERC) calls hydrokinetic technology — dam-free. These pioneers are “way out on the bleeding edge,” said Mike Sale, a Bethesda, Md., energy consultant and Department of Energy veteran. Yet Sale admires them. “They’re trying to develop a new area and having to learn some hard lessons,” he said.
In Minnesota, Hydro Green’s hard lesson is patience. The firm received city approval in 2006 but only this year expects to get blades in the water. FERC is key — and may want to lower barriers for new technology. Said FERC Commissioner Jon Wellinghoff: “I don’t see any show-stoppers in the offing.”
Marc Hequet is a writer in St. Paul, Minn.
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