First in the world
History will be made no later than the end of the month at Enel Green Power’s Stillwater geothermal/solar plant northeast of Fallon.
A 2-megawatt capacity power project that is wrapping up construction will operate alongside the geothermal plant and the solar photovoltaic facility to give the world the first facility that produces energy from three separate energy sources.
Enel vice president of engineering and construction, William Price, led a small group on a two-hour tour of the plant earlier this week. He said construction began in April, and the plant will begin producing thermal energy later this month. Price said 22 rows of solar concentrating mirrors allow the power of 75 suns on the solar tubes.
“This is a unique project,” Price said, “The first time it has been done. This particular unit with three technologies is the first.”
According to Price, each row is 700 feet with each mirror spanning 20 feet across. He said the panels cover 21 acres on land that was once used for agriculture.
“The panels are 16 feet high, and we’ve installed the panels in pieces,” he said. “Inside the middle is a 5-inch pipeline with hot water.”
One of the challenges with this new solar mirror field will be preventing weed growth.
“It will be challenging to keep the vegetation down,” he said. “If the vegetation grows high, it affects solar and becomes a fire hazard.”
Since Enel’s Stillwater and Salt Wells plants began producing energy in the spring of 2009, Nevada has emerged as one of the top geothermal producing states in the country. In 2012, Enel dedicated a solar plant, complete with 89,000 solar panels, to augment its generating power.
In 2013, for example, the geothermal plant generated enough renewable electricity for 40,000 households, while the solar plant met the energy needs of 16,000 more homes. Price said NV Energy buys Enel’s power.
The newest venture, though, is state of the art technology.
“When Enel first looked at this project, we had available area,” Price said. “It was a good opportunity to use the exisiting facilities and add the hybrid project to it.”
Enel explained in a handout the general intent: “This is the first hybrid plant in the world able to bring together at the same site the continuous generating capacity of binary-cycle, medium-enthalpy geothermal power with soar photovoltaic and solar thermodynamic.”
Price said the binary cycle extracts the heat from underground rocks to turbines that generate electricity. As he walked along the mirrors, Price said the underground hot water is pumped from a geothermal well to the ground’s surface through a series of heat exchangers.
Price pointed to the closed loop system, explaining how the water flows, which leaves the internal heat exchanger, through the secondary loop outside the building to exchange heat with the ground before returning. He added the system will not experience any water loss or carbon emission generated by the panels. He said the procedure involves 300-degree water flowing through the pipes and heat exchanges to the geothermal plant.
Furthermore, Enel Green Power, the National Renewable Energy Laboratory and Idaho National Laboratory, under the oversight of the U.S. Department of Energy Geothermal Technologies Office, have signed a cooperative research and development agreement to explore the potential of Enel’s Stillwater hybrid power plant.