SolarReserve / PR News
Monday, July 6, 2015 | 2 a.m.
Where is solar energy headed in Nevada?
Owned by SolarReserve, the Crescent Dunes 110-megawatt concentrated solar power project in Tonopah was supposed to open in 2014 but experienced delays. It is in the commissioning phase now and is scheduled to open later this year. It is the state’s largest solar power plant.
Thanks to an advanced energy storage system, officials say, it can produce power for customers even at night and when it is cloudy.
By comparison, the Ivanpah Solar Electric Generating System near the California-Nevada border was expected to produce enough electricity to power a city of 140,000 homes when it opened in early 2014, but in its first year, the plant produced only about half of its expected annual output. Clouds, jet contrails and weather had a greater effect on the plant than the owners had anticipated.
The Crescent Dunes project uses 17,500 heliostat mirrors to focus the sun’s thermal energy to heat molten salt that flows from a 640-foot solar power tower to underground storage tanks, where the salt is used to produce steam and generate electricity. The salt can withstand a very high temperature without melting and can be used to store energy. Excess thermal energy is stored in the molten salt and can be called upon at any time to create additional power in the evening or when direct sunlight isn’t available, increasing the stability of the grid and reducing the need for carbon pollution-emitting generators.
The Crescent Dunes array is the first of its kind in the United States and the tallest molten salt tower in the world.
The state basks in an average 250 sunny days a year, and the push to turn our clear skies and sun rays into energy grows every year.
In fact, Las Vegas is the third-sunniest city in the country, tied with Phoenix and Tucson, and just behind Yuma, Ariz., and Redding, Calif., according to the National Oceanic and Atmospheric Administration.
Nevada also ranks third in solar energy produced per capita, at 122.9 watts, trailing only Arizona and Hawaii. Nevada falls fourth in total amount of energy produced by solar power, behind Arizona, California and New Jersey.
There is enough solar capacity in the state to power 64,000 homes for a year, according to the trade group Solar Energy Industries Association, and Nevada installed 47 megawatts of new solar energy capacity in 2013, ranking 12th nationally. New projects and players in the field emerge frequently.
By state law, a certain percentage of electricity provided by NV Energy must come from renewable resources, with a specific emphasis on solar power. By 2021, NV Energy must build or acquire renewable energy sources capable of producing at least 50 megawatts. After 2016, 6 percent of NV Energy’s retail electricity must come from solar plants, and by 2025, 25 percent must come from renewable sources.
Stephen Brown, director of UNLV’s Center for Economic and Business Research, says commercial solar power in Nevada is more economically viable than other renewables, such as wind power, but still has a long way to go to be cost competitive.
“We’re still at a point where neither solar nor wind energy would be used for providing electricity in Las Vegas if it weren’t for the regulatory push,” Brown said. “If you put yourself in an isolated part of Nevada, where you’re not close to the electricity grid, then wind and solar energy may be attractive economically.”
Engineers and scientists are working on thinner, lighter materials to turn sunrays into electricity and designing new methods of storing power.
Renewable energy sources still are troubled by intermittency issues. Solar and wind power systems need backup from conventional energy sources to take over when the sun isn’t shining or the wind isn’t blowing.
Valley Electric Association is a nonprofit co-op utility that has more than 17,000 members and was founded in 1965 to serve the electrical needs of farmers. As a relatively small utility with customers in California and Nevada, the association has taken up several projects aimed at expanding the use of solar energy.
In 2013, the co-op left the NV Energy Balancing Authority and joined the California Independent System Operator Corporation, which manages California’s electricity grid, to allow renewable energy producers in Southern Nevada to transmit and sell power to other markets.
The co-op also partnered with the Renewable Energy Test Center, an engineering services provider and tester of renewable energy products in California. The center tests solar energy systems on Valley Electric property, then the organizations donate the power to local senior centers.
On a residential scale, Valley Electric has installed hundreds of solar water-heating systems in people’s homes, which are expected to save up to $500 a year in energy costs, through a program in which all of the upfront costs are paid by the association and customers are charged a monthly fee. Co-op officials say the systems, which use sunshine to warm a heat-transfer fluid that is pumped into the water heater, eliminate 85 percent of a typical home’s annual energy use to heat water.
The association also is looking into solar gardens, patches of land where the utility could operate photovoltaic panels and use the electricity to power nearby homes or apartments.
New storage techniques
Like the salt system that will be used at Crescent Dunes, some of the most interesting developments in renewable power involve energy storage.
For example, Advanced Rail Energy Storage, headquartered in Santa Barbara, has developed a large-scale system of storing energy using electric locomotives. The company uses train cars loaded with rocks to store solar energy that can be used when the sun isn’t shining.
The trains, powered by the electricity they generate but don’t use when it’s sunny, are driven up hill, then when the power is needed, the trains roll downhill using the force of gravity while their motors work as generators.
Valley Electric is partnering with Advanced Rail Energy Storage to bring the technology to Nevada.
“We do believe it is a great breakthrough in technology,” Valley Electric CEO Tom Husted said. “It uses the natural terrain — terrain we have in abundant supply in Nevada — for grid energy storage and without the need for water resources.”
Utility-scale solar energy projects primarily include photovoltaic systems that convert sunlight into electric currents or concentrated solar power systems that use mirrors and tracking devices to focus a large area of sunlight into a concentrated beam that is used as a heat source for conventional power plants.
Photovoltaic panels can be clustered on a roof to power a home or business, or spread across large swaths of land for utility-scale production.
Commonly known as solar cells, photovoltaic cells are made of semiconductor materials and come in sizes and shapes that range from smaller than a postage stamp to several inches across. The modules can be connected to form arrays of different sizes and with variable power outputs.
When light shines on a PV cell, electrons are knocked loose from the atoms in the cell’s semiconductor material. If electrical conductors are attached to the positive and negative sides, the electrons can be captured as electricity.
Concentrated solar power
Concentrated solar power systems, such as the one built in Ivanpah, Calif., use fields of mirrors to focus sunbeams, creating a heat source for conventional power systems.
At Ivanpah, for example, more than 300,000 computer-controlled mirrors track the sun in two dimensions and reflect the sunlight to boilers that sit atop three 459-foot towers. When the super beam of sunlight strikes the boiler pipes, it heats the water to create superheated steam. The steam then is piped from the boiler to a turbine, where electricity is generated. From there, transmission lines carry the power to homes and businesses.