Big solar in the desert is controversial — and no big solar plants are more controversial than solar thermal power tower plants.
Supporters of the huge plants laud power tower thermal technology for its promise of straightforward energy storage, large potential energy generating capacity, and their symbolism as monuments to a dawning age of climate-safe power. The plants critics voice concerns about destruction of habitat to build the plants, their cost, their relative inflexibility compared to other forms of solar, and their potential damage to wildlife.
All those arguments boil down to one basic truth: Solar power tower plants are really, really big. In his short documentary on Nevada's Crescent Dunes Solar Project, filmmaker Alec Ernest vividly shows us just how big.
Crescent Dunes is a 110-megawatt power tower project northeast of Tonopah, Nevada, owned and operated by the company SolarReserve. Its 10,347 large mirrored heliostats, each of them 42 feet wide, focus solar energy to a boiler atop a 540-foot tower. There, the energy is used to heat molten salt — not table salt, but a mixture of sodium nitrite and potassium nitrite. That molten salt is then used to create steam, which drives a power-generating turbine. The advantage of molten salt? It stores heat, allowing Crescent Dunes to generate power for some time after sunset.
Online since 2015, Crescent Dunes delivers power to utility NVEnergy, which serves about half of Nevada's geographic area, and the vast majority of its population.
As Ernest shows, Crescent Dunes — the world's largest solar power tower plant with thermal storage — is a mindbogglingly large project. That palpable size will likely give both big fans of solar and foes of big solar fuel for their arguments.
Crescent Dunes workers are dwarfed by the heliostats they built methodically and carefully, and those heliostats are dwarfed in turn by the plant's power tower.
But there's no dwarfing the palpable pride displayed by the plant workers Ernest portrays. Whether it's pride in painstakingly precise construction or in the plant's main purpose: to provide energy without burning coal or natural gas.
One of the engineers Ernest talked to sums it up succinctly. "This is the absolute best I've ever done in my life."