For anyone who happens to be driving by the Crescent Dunes Solar Energy Plant near Tonopah, Nevada, they are in for a shocking sight. They will see a massive tower with a glowing tip, surrounded by an almost 2-mile-wide circle of thousands of reflective squares. The luminous quality of the plant, coupled with its sleek design, gives it the appearance of an art installation or a set from a science fiction film. But the project’s entire form is determined by its function — the storage of solar energy.
Solar energy is taking off across the United States. With various technological advancements leading to reduced costs, the renewable energy sector is thriving. However, after decades of struggling to get the technology off the ground and running, the industry has run into a new problem, one that has nothing to do with regulations or competition from other industries. Instead, scientists are contending with nature itself, as they try to determine the best methods for storing the solar energy being generated through the day for use during the night. Crescent Dunes may just serve as an ideal solution.
How the Crescent Dunes Plant Functions
The reflective squares, known as “heliostats,” are engineered to direct heat from the hot Nevada sun to the top of the tower. Their circular arrangement spans 1.75 miles, and is engineered to optimize light deflection for maximum efficiency.
The tip of the tower glows white due to the intensity of the heat being directed from the heliostats. Using a system of pipes and tanks, molten salt is sent up to the top of the tower, heated, and then sent back down. Unlike common salt, molten salt “actually looks like water,” says Kevin Smith, CEO of SolarReserve, the company behind Crescent Dunes. This makes the trip to the top of the tower much more efficient.
To retain this quality, the temperature must stay above 450 °F. Once heated and sent back down, the salt reaches 1050 °F. That heated molten salt is then used to make steam for generator power. Through this process, Crescent Dunes is able to generate energy for up to 10 hours after the sun goes down. “We have enough energy in storage so that we can generate at night,” says Smith. There’s enough energy, in fact, to power 75,000 Nevada homes.
Key Challenges and Concerns
The plant has faced a few hurdles, however. For example, birds were flying into the extreme heat generated from the mirrors and being incinerated. The Bureau of Land Management says that the mirrors have since been adjusted to minimize the risk of these gruesome occurrences.
Also, some people have argued that these plants should be erected closer to cities, rather than in wild areas where ecosystems may be disrupted.
Finally, the cost of Crescent Dunes electricity is more than that of the power provided from natural gas. However, Smith argues that the main costs are associated with the expensive construction involved, coming in at $997 million. With future iterations being built more efficiently, the costs will decrease over time. And as Smith puts it, “Once the plant is built, the fuel is free,” and the storage capacity serves as an added value.
A Bright Future
If Smith’s predictions hold true, these visually arresting solar plants will likely start popping up all over the United States, wherever there is room to build them. Currently, SolarReserve operates 10 such facilities across the globe, including a second plant in Nevada.
Harnessing nature’s potential and then implementing human ingenuity to capture the sun’s energy when it sets? It sounds like something right out of a movie, but it’s quickly become a new, renewable reality.
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