N.Y. Power Authority Completes Four-Year Upgrade of Blenheim-Gilboa Pumped Storage Project

The New York Power Authority’s (NYPA) completion of a Life Extension and Modernization Program at its Blenheim-Gilboa Pumped-Storage Power Project in Schoharie County enhances the hydroelectric facility’s contributions to the state’s electric power system.

The New York Power Authority marked the completion of a nearly four-year overhaul of its Blenheim-Gilboa Pumped Storage Power Project in the northern Catskills at an event Thursday where NYPA President and Chief Executive Officer Richard M. Kessel was joined by state and local officials in highlighting the milestone. NYPA’s Life Extension and Modernization (LEM) effort will improve the reliability of critical electricity infrastructure and increase the Power Authority’s ability to help meet the long-term energy needs of the state.

“The on-time and on-budget completion of the Life Extension and Modernization Program at Blenheim-Gilboa is a hallmark of achievement for all of those who’ve been involved with the nearly four-year initiative, which secures the future of this special hydroelectric facility for decades to come,” Kessel said. “B-G’s value to New York State is especially apparent during the air-conditioning season when the margins between available electricity supplies and power consumption narrow the most, and market electricity costs tend to rise. For that reason, the completion of the project’s refurbishing ahead of the peak-demand months is good news for the state’s electric power system and ratepayers, and something to celebrate.”

On May 22, the Power Authority returned to service the last of B-G’s four pump-turbine generating units to undergo replacement as part of the more than $135 million upgrade of the 37-year-old facility, which recycles water between lower and upper reservoirs to generate power when it is most needed, generally in the late afternoon or early evening. The more efficient, modern units allow the pumped-storage project to produce additional power from the falling water from the upper reservoir on Brown Mountain, with the total capacity of the facility increased by 120 MW, or 11.5 percent, to 1,160 MW.

“Our maximizing of B-G’s efficiency—and its ability to generate more power from the same amount of water—contributes to the overall reliability and flexibility of the state’s electric power system,” Michael J. Townsend, NYPA chairman, said. “This has been a vital initiative for enhancing the project’s capability for harnessing the stored water from the project’s upper reservoir to produce economical power during the times of peak demand. The Life Extension and Modernization Program also reflects the priority the Power Authority has long given to being a good steward of its hydroelectric resources, which account for nearly 80 percent of its statewide power generation.”

NYPA began the LEM at Blenheim-Gilboa, which is the fifth largest pumped storage project in the nation, in September 2006 when the first of the four pump-turbine generating units was taken out of service for refurbishing. The process was repeated three times, in the fall of 2007, 2008 and 2009, with each unit returned to service by the following summer with an increase in maximum capacity from 260 mw to 290 mw per unit. (While the physical work for the LEM began in 2006, the engineering and procurement for the initiative commenced in 2003.)

The phased-in approach to B-G’s refurbishing limited the impact of equipment being taken out of service. During each phase of the multiyear upgrade, three pump-turbine generating units were operating, except for an approximately two-month period at the beginning of each stage, around the start of fall. In the course of that period, the water level in the upper reservoir, which has a capacity of five billion gallons, was substantially lowered in order to accomplish the replacement of a spherical valve on the unit being refurbished. The valve controls the flow of water into the pump-turbine generator.

In addition to replacing the turbine-generators and spherical valves, the upgrade included replacement of main power transformers, circuit breakers, exciters and related equipment.

“The challenging schedule of the LEM required the just-in-time delivery of new and conditioned parts from manufacturers to support the critical path of the job, while taking into account the limited space at the facility for storing large components like the generator rotors, which weigh about 500 tons,” Lynn Hait, B-G regional manager, Central New York, said. “Throughout the upgrade, we were acutely conscious of the importance of each phase being completed by June, in time for the summer peak demand season. The fact that we achieved this during each of the four successive years of the program is a credit to the NYPA engineers and other staff members who gave their all to this endeavor.”

Hait noted that whenever possible, NYPA relied on its own employees to undertake the work. In instances where B-G staff members were otherwise engaged, the Power Authority or its contractors used artisan and craftsmen from the project area and other local trades people.

The LEM program marked the first major overhaul at B-G since it went into service in July 1973 at its Schoharie Creek site in the Towns of Blenheim and Gilboa in Schoharie County, about 40 miles southwest of Albany. The Federal Energy Regulatory Commission, the regulatory organization responsible for licensing the nation’s nonfederal hydroelectric projects, authorized the work.

The pumped-storage project is designed to operate like a giant storage battery. At times of peak demand, hundreds of thousands of gallons of water are released from B-G’s upper reservoir, plunging 1,200 feet through a 28-foot diameter vertical shaft within Brown Mountain. The water drives the project’s four turbine-generators before flowing into the lower reservoir on Schoharie Creek, just below the powerhouse, where the equipment is contained.

At night and on weekends, when demand is lower, the water is pumped back to the upper reservoir using economical electricity from the most efficient thermal generating units.

Pumped-storage is a closed-cycle. The same water is used repeatedly except for that lost through natural evaporation.

Like conventional hydroelectric projects, pumped-storage facilities are designed to respond to electric power system demand and emergencies more quickly than thermal plants, with hydro facilities able to go from startup to full power in a matter of minutes. The completed overhaul at B-G enhances the facility’s capability for carrying out that role.

The B-G project has a staff of 139 employees and an annual payroll of about $11 million.

The Power Authority is currently conducting a LEM program at its St. Lawrence-Franklin D. Roosevelt Power Project in Massena, with that initiative more than three-quarters complete and scheduled to be finished by 2013. It also completed a 15-year upgrade of its Niagara Power Project, in late 2006, to enhance the efficiency of that project’s main generating facility, the Robert Moses Niagara Power Plant, and extend its operating life.