Hydro Review: Celebrating More Than a Century at Blewett Falls Hydro

0
54

Altered Energy – Alternative Energy news

With its historic significance to the region and its continued reliable operation for more than 100 years, the 24.6-MW Blewett Falls Hydro Station is a natural choice to join our Hydro Hall of Fame as a 2018 inductee.

By Kim Crawford and Michael Brissie

Located on the Pee Dee River between Anson and Richmond counties in south-central North Carolina, Duke Energy’s Blewett Falls Hydro Station has been providing clean, renewable energy since 1912. The 24.6-MW station still operates the original six horizontal generating units with a quad-runner turbine arrangement.

For its historical significance and long life, Blewett Falls was a 2018 inductee into the Hydro Hall of Fame.

Blewett Falls and early pioneers of hydropower

The roots of Blewett Falls Hydro began in the late 1800s when early pioneer William Blewett recognized the usefulness of the natural falls along the Pee Dee River and applied for land grants to operate a fishery and ferry at the location. The expansion of the textile industry in the early 1900s created interest in using the river to provide power to cotton mills and towns near Rockingham, N.C.

Another visionary, Hugh MacRae, also saw the potential at Blewett Falls and, in 1905, obtained a charter for the Great Pee Dee Electric and Power Company. By the following year, its name had been changed to Rockingham Power Company.

Located in the Uwharrie Lakes region in North Carolina’s Central Piedmont, the hydroelectric project area is characterized by forested rolling hills and open rural farmland, accentuated by one of the oldest mountain ranges in North America – the Uwharrie Mountains.

After enlisting the Colonial Securities Company of Boston and the Knickerbocker Trust Company of New York each for one-third interest in the company, MacRae picked up the last third and started working toward a June 1909 completion date for the new hydropower project. Work on the Blewett Falls dam began in 1905, with as many as 1,200 men – blacks and whites, Swedish and Italian immigrants — conducting the very dangerous work of constructing the facility.

Construction of the powerhouse at Blewett Falls

Blewett Falls is a concrete gravity dam about 15 miles north of the North Carolina-South Carolina state line. The dam consists of 1,700 feet of earthen embankment, 1,468 feet of ogee concrete spillway and 300 feet of powerhouse intake section. The dam has a maximum height of about 50 feet above the river bed and forms the Blewett Falls Lake. Blewett Falls Lake extends about 10 miles upstream from the dam, encompassing 2,866 acres.

An ensuing economic panic in 1907, combined with flooding rains the following year, began creating serious construction delays. Ultimately, due to financial losses, the property was sold at auction in 1909 for $1 million to a group of bondholders who later formed the Yadkin River Power Company. At the time of the sale, the facility was 80% complete.

The project superintendent who completed the construction at Blewett Falls, Frank C. Abbott, instituted night shifts to complete the project by December 1911.

The station, a four-story brick superstructure on a concrete substructure, began commercial operation on June 1, 1912. Water is directed through a 200-yard-long canal and flows into the generating equipment through 17-foot-diameter penstocks. A 40-ton crane inside the powerhouse is used to handle equipment inside the generator room. On the exterior, a 10-ton crane spans the intake dam to the powerhouse and is used for servicing the turbines.

Installation of the generating units at Blewett Falls

At the time it was completed, the Blewett Falls project was the most impressive man-made structure in the region. News accounts at the time quote eyewitnesses describing the spillway as “A glorious waterfall, the biggest North Carolina has yet seen.”

Changes over the years

Severe flooding events in 1917 and 1945 resulted in the installation of earthen embankments, raising the intake dam by 4 feet and installing flashboards along the dam.

A subsidiary of Electric Bond & Share Company, Yadkin River Power was managed in conjunction with Carolina Power & Light (CP&L) until merging with CP&L in 1926.

In 1971, CP&L nearly quadrupled the generating capacity of the site by adding four 17-MW natural gas combustion turbine-generator units that continue to operate during periods of peak customer demand.

The Blewett Falls powerhouse was deemed eligible for listing on the National Register of Historic Places in 2006. Primarily an industrial design, the building reflects the style of other powerhouses of the period. Segmental arched windows, a unique spiral staircase, and an arcaded basement level add to the historic character of the structure. Modifications including large concrete flood plugs and the removal of lower-level windows were incorporated to mitigate future potential flooding of the powerhouse.

Interior of the historic powerhouse at Blewett Falls

Duke Energy acquired Blewett Falls Hydro in 2012 through a merger with Progress Energy, formerly CP&L. Blewett Falls is located about 29 river miles downstream of Duke Energy’s Tillery Hydro Station. Both stations are part of the Yadkin-Pee Dee Hydro project, which includes Tillery and Blewett Falls lakes.

Duke Energy has continued to invest in Blewett Falls, completing the first generator rewinds and collector ring replacements on the original generators installed during the plant’s construction, from 2012 to 2017. During this same time frame, excitation systems were also replaced.

Additionally, remote operation capabilities were added to Blewett Falls in 2017 to allow centralized monitoring and operation to fully integrate the station into the Duke Energy fleet of 32 hydro stations in the Carolinas.

Other recent improvements to the station demonstrate the value of renewable hydro generation in the Carolinas. A dissolved oxygen system was installed in 2010 to improve downstream water quality. Station transformers also were replaced in 2010 to reduce the risk of environmental impacts, and the station’s three original single-phase water-cooled generator step-up transformers were replaced with a single, air-cooled GSU transformer.

At full pool elevation, the lake contains about 34 linear miles of shoreline and provides numerous recreation opportunities to the public. Public recreation includes a dam canoe portage, a fishing platform at the powerhouse, a small boating access area and a recently renovated larger boating access area with multiple ramps and picnic facilities.

Blewett Falls Dam and its scenic surroundings

The scenic and tranquil characteristics of this area provide a wide range of recreational activities, including hiking, horseback riding, boating, fishing, camping, swimming, picnicking, mountain biking and off-road vehicle access.

Looking toward the next 100 years

For more than 100 years, Duke Energy has been harnessing rivers to generate clean renewable energy. The company’s hydro stations, like Blewett Falls, have helped add other renewables, such as solar, to the grid because these units can be brought online quickly to help manage rapid shifts in power demand.

The station continues to be used as a peaking site during low flows. With normal rainfall, the station runs around the clock for months at a time, with the units dispatched from a central location in Charlotte, N.C.

In 2015, Duke Energy received a new 40-year operating license for the Yadkin-Pee Dee Hydroelectric Project from the Federal Energy Regulatory Commission. Implementation of the new license requirements has improved water quality and aquatic habitat downstream of the station by providing continuous minimum flow releases through hydropower generation.

The minimum flow agreement also includes installing a fish passage facility to provide additional spawning and rearing habitat for American shad and American eel upstream of Blewett Falls Dam. This project is ongoing, with anticipated completion in 2022. Other benefits of the new license include public recreational enhancements and land conservation.

With focused improvements over the years, this historic hydro station will continue to provide peaking and load-following generation well into the future.

Kim Crawford is lead communications consultant and Michael Brissie is general manager, hydro east-regulated renewables, fossil hydro operations with Duke Energy.

Original Source