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Hydroelectric plant hums along

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By Katy Korkos

Los Alamos County’s two hydroelectric power plants are humming along this winter, thanks to plenty of water in the reservoirs behind both El Vado and Abiquiu dams. Though winter is often a slow time, where operators do routine maintenance, but this year the water keeps on flowing so the turbines keep on spinning.The Abiquiu plant has a rated capacity of 13,800 kilowatts with both Francis turbines working. At Abiquiu, a 340-foot high dam impounds the Chama River to create a 5,200-acre reservoir, more than 12 miles long. The El Vado dam is 154 feet tall and designed to create a storage capacity of 195,440 acre-feet. Both reservoirs were created to provide irrigation water and flood control, and the generation of power is an added bonus.Water releases are controlled by the Army Corps of Engineers.Tom Biggs,  deputy utilities manager for the power supply department, has worked for the department for as long as hydroelectric power has been part of the county’s supply.The El Vado plant came on-line on Biggs’ first day of work for the county – May 2, 1988 – and the two plants have combined to produce over one billion kilowatt hours (kWh) since that time, according to a report from the Department of Public Utilities.To drive the turbines, water is channeled from the reservoir into a 12-foot diameter penstock, which is lined with stainless steel. The water turns blades, which rotate a metal shaft in the generator above, and that energy becomes electricity in the coils above that, where the exciter is located.The electricity then passes through a transformer, which converts it to volts for transmission.The county uses about 20 percent and the laboratory uses the other 80 percent of the county’s electricity, whether it comes from the hydroelectric plants or from coal-fired plants.“Power dispatchers at TA-3 match the resources to the total load,” Biggs said.The plants are fully automated, and require that operators maintain all of the systems and back-up systems daily. Although each plant requires only one operator to keep it running, the operators will often travel from El Vado to Abiquiu to work as a team on maintenance jobs in the isolated facilities. Plant operator Bobby Trujillo has worked for the county since 2000, and lives in the village of Abiquiu.“We work together for safety reasons,” Trujillo said. The turbine blades, the working heart of each generator, are maintained annually.The water flowing out of the pipe at the bottom of the dam is water that has been used to cool the generator. When more water is released from the reservoir than can be used by the generators, it passes through pressure releasing valves. The cone valves are designed to dissipate the energy from a water flow during reservoir discharge without causing erosion to the surrounding environment. The plant also adds dissolved oxygen into the water before it is released into the river, to support wildlife habitat.Biggs said that the county is planning to acquire a third generator for the Abiquiu plant, which was designed to accommodate a third piece of equipment. The low-flow generator would be used when there are 100-200 cubic feet per second available.He said that a contract had been written and approved at one point, but never fulfilled due to a technicality in the contract. To install an additional turbine, Biggs added, a coffer dam would have to be built to keep water away from the construction area. He said contractors are not enthusiastic about finishing the work in the short time period where water is not  released from the dam, usually during the winter months.Public Information Officer Julie Williams-Hill said that a new low-flow unit would give the county renewable energy credits, which the older units do not qualify for.The cost of producing the electricity by the hydroelectric plants is typically about 8-11 cents per kilowatt hour, according to a Department of Public Utilities report from 2006.In 2015, the bonds used to pay for the plants will be fully amortized and the county will retain ownership of the plants under the Electric Coordination Agreement  between the county and the Department of Energy. “When the debt service is repaid, the Abiquiu plant will generate power for about 3.3 cents per kilowatt hour,” according to the report.