SMALL HYDROsnohomish county pud

Small Hydro in the Pacific Northwest

Two thousand years ago, the Greeks learned to harness the power of running water to turn the massive wheels that rotated the shafts of their wheat flour grinders. Today, small hydropower is taking this ancient concept and pairing it with state-of-the-art technology to create a renewable energy resource. Run-of-the-river systems, which do not require large storage reservoirs, can be used for small-scale hydro projects (less than 30 megawatts), which have minimal effect on the natural environment and are carbon-free producers of electricity.

Snohomish County PUD owns two run-of-the river, low impact hydroelectric projects in central Snohomish County. The 650 kW Woods Creek project is in operation while operation of the 7.5 MW Youngs Creek project is schduled to go on-line in 2011.

The PUD has been taking a new look at low impact hydroelectric projects over the last few years as they are a clean, renewable resource with long lifespans. They have a production profile that matches Washington’s winter peak load and can be built locally. With careful consideration to siting, design and maintenance, these projects have minimal environmental impacts.

In the US today, hydropower projects provide 81 percent of the nation’s renewable electricity generation and about 10 percent of the nation’s total electricity.

““

Small, low-Impact hydro fits with our commitment to meeting customers’ needs through a diverse mix of renewable technologies and conservation. We are blessed to live in a region with mountains and rainfall, and it makes sense to look to these locally generated clean resources. They also can be easily and efficiently integrated into the electrical grid without requiring hundreds of miles of new expensive transmission line.

Steve KleinSnohomish County PUD General Manager

How a site is picked to minimize impact

� Diversion and powerhouse are above a natural salmon barrier.

� Outside federal wilderness areas.

� Outside federal wild and scenic river corridors.

� No known geological or unstable areas that would preclude construction.

� Located in close proximity to an existing transmission system.

� No impacts to old-growth forests or ESA species.

� Typically in commercial forestry lands or other previously developed areas.

Factors which minimize impacts

� Small or no reservoir means flow and temperature of water are unchanged.

� Sited at or above existing natural barriers to salmon migration.

� Small weir is overtopped several times per year, naturally washing sediments downstream.

� Minimum flows are released to maintain proper flows for local fish and aesthetics of waterfalls in the bypass reach.

� Transmission lines are typically placed along existing roadways.

� Buried pipeline corridor is planted with native plants.

� All water is returned to river.

� Where possible, existing facilities are utilized.

A 1 MW system can provide enough power for 750 homes.

Downstream Reach

Buried Transmission Line

Powerhouse

BuriedPenstock

Bypass Reach

Small Diversion Weir

NaturalSalmon Barrier

Return Flow (Tailrace)

The PUD has met with and sought input from local tribes, the

state and federal resource agencies, non-governmental

organizations and interest groups prior to filing for licenses

for any of the new sites being considered.

How the technology worksFor run-of-the-river hydro projects, a portion of a river’s water is diverted to a pressurized pipeline (penstock) that delivers it to a turbine. The moving water rotates the turbine, which spins a shaft. The motion of the shaft is used to power a generator to generate electricity. A site with a large natural elevation drop is desirable because less water is required to produce a given amount of power.

A programmed computer at the powerhouse constantly monitors the amount of flow in the stream and adjusts the flow through the turbine, based on what is available. If

flows in the stream fall to state-designated minimums, the powerhouse stops generating and all the flow runs down the stream without being diverted.

Project elements such as the pipeline and transmission line are typically buried, and the powerhouse is designed to blend into the existing setting. When possible, existing facilities such as dams not used for generation or drinking water systems are developed for small hydro.

Small hydro facilities must obtain a license from the Federal Energy Regulatory Commission, a multi-year process that requires extensive studies and collaboration to address stakeholder concerns.

Low Impact Hydro InstituteThe Low Impact Hydropower Institute (LIHI) is a national independent environmental non-profit organization with a mission of reducing the impacts of hydropower dams. It certifies dams that adequately protect or mitigate their impacts in eight key resource areas: river flows, water quality, fish passage and protection, watersheds, threatened and endangered species, cultural resources or public access and recreation opportunities. It also requires that dams not have been recommended for removal.

While the PUD’s low impact sites meet these criteria, LIHI excludes new dam construction—if dams were not built by August 1998, they are not eligible for certification. Therefore, the PUD may build new dams as part of projects that meet all LIHI requirements, but they would not be eligible for LIHI certification.

www.snopud.com/hydro