MARIA ELENA, Chile - On the solar farms of the Atacama Desert, the workers dress like astronauts. They wear bodysuits and wraparound sunglasses, with thick canvas headscarves to shield them from the radiation.
The sun is so intense and the air so dry that seemingly nothing survives. Across vast, rocky wastes blanched of color, there are no cactuses or other visible signs of life. It is Mars, with better cellphone reception.
It is also the world's best place to produce solar energy, with the most potent sun power on the planet.
So powerful, in fact, that something extraordinary happened last year when the Chilean government invited utility companies to bid on public contracts. Solar producers dominated the auction, offering to supply electricity at about half the cost of coal-fired plants.
It wasn't because of a government subsidy for alternative energy. In Chile and a growing list of nations, the price of solar energy has fallen so much that it is increasingly beating out conventional sources of power. Industry experts and government regulators hail this moment as a turning point in the history of human electricity-making.
"This is the beginning of a trend that will only accelerate," said Chilean Energy Minister Andrés Rebolledo. "We're talking about an infinite fuel source."
President Trump ordered U.S. regulators this week to reverse Obama-era policies aimed at curbing greenhouse gas emissions, and he has promised to "bring back" the U.S. coal industry. But construction of coal-fired power plants dropped 62 percent over the past year worldwide, according to a survey by the Sierra Club and other activist groups. In China last year, the number of new permits for coal-fired plants fell by 85 percent.
More worldwide generating capacity is being added from clean sources than coal and natural gas combined, according to a December report by Bloomberg New Energy Finance, which closely tracks investment in renewable energy.
An investor in Chile wanting to build a hydroelectric dam or coal-fired plant potentially faces years of costly political battles and fierce resistance from nearby communities. In contrast, a solar company can lay out acres of automated sun-tracking panels across an isolated stretch of desert and have them firing quiet, clean electricity in less than a year, with no worries about fluctuating fuel prices or droughts. The sunlight is free and shows up for work on time, every morning.
Long dependent on energy imports, Chilean officials now envision their country turning into a "solar Saudi Arabia." Chile's solar energy production has increased sixfold since 2014, and last year it was the top-scoring clean-energy producer in the Americas, and second in the world to China, according to the Bloomberg rankings. (China is the world's largest producer of greenhouse gases but also the leading investor in renewable energy.)
Driving the global shift to cheap sun power is a dramatic decline in the cost of the photovoltaic (PV) panels that can be used to create giant desert solar farms or rooftop home installations. China produces more than two-thirds of the world's PV panels, and their price has fallen more than 80 percent since 2008.
If the trend does indeed symbolize a turning point, that doesn't mean every country is on board with the global green-energy conversion.
Trump's executive order this week rolled back restrictions on the coal industry and struck down a slew of other measures intended to limit carbon emissions, including requirements that federal officials take climate change into account when making regulatory decisions.
Electricity production is the largest source of U.S. greenhouse gas emissions, and more than two-thirds is generated from fossil-fuel sources, according to the most recent data from the Environmental Protection Agency. The United States last year pledged with other members of the Group of 7 nations to phase out subsidies for oil, gas and coal by 2025.
But meeting such goals remains politically contentious in the United States, with an existing network of conventional power plants and jobs that depend on them. Nations such as Chile can take a different path.
Chile is adding solar plants because they fulfill the country's goal of 60 percent clean energy by the year 2035. But mostly it is adding them because no other energy source can compete with the awesome sun power of the Atacama Desert.
Unlike many of South America's other major countries, Chile has virtually no oil or gas deposits. With a heavy dependence on imported fuel, Chileans have been paying some of the highest electricity rates in the region, but prices are falling as renewable sources come online.
The Atacama is well-suited to solar energy production for the same reasons astronomers put high-powered telescopes in northern Chile for the clearest possible Earth-based views of the cosmos.
In nations such as Japan and Germany, which are some of the world leaders in solar-energy production, the sun's rays are partly diffused by water molecules floating in the air, even on days when it isn't cloudy.
But in the super-dry Atacama, where it virtually never rains, the photons beam straight down. Put a solar panel beneath them, and it's like plugging into the sun.
At the Finis Terrae solar plant near the tiny town of Maria Elena, more than 500,000 PV panels blanket the desert. The 160-megawatt plant was the largest solar installation in Latin America when it went online last summer, capable of powering nearly 200,000 homes. Since then, another Chilean plant has surpassed it.
Outside the plant's operations center, a worker-safety chart rated the day's ultraviolet radiation levels on a scale of one to 10. "Eleven," it read. "Extreme."
"Compared with the Arabian, Sahara and Australian deserts, the Atacama Desert has the highest levels of direct normal irradiation, the key component of the sun's rays for energy production," said Salvatore Bernabei, the head of renewable energies for Latin America at Enel Green Power, an Italian multinational that owns the plant.
The radiation is so intense that no one is really sure how long standard-issue PV panels - which are designed to last 25 years - will be able to withstand it. One solar plant here had to replace most of its exposed cables after six months because the radiation fried their insulation.
Another problem solar companies are facing is the desert soil. In the afternoons, writhing dust devils zigzag across the desert floor, sprinkling particles onto the panels and reducing their output. Plant managers try to keep them clean using specially outfitted tractors with long wiper-arms, but there's little water available.
Chilean energy officials say these challenges are relatively minor. The country derives about 6 percent of its energy from solar, but the potential of the Atacama is so great that Chile could generate all of its electricity with about 4 percent of the desert's surface area, if there were a way to efficiently store and distribute that energy.
"We've been thinking for so long that we're poor in energy resources, but we're really rich," said Rodrigo Mancilla, who leads a commission on solar power at Chile's Ministry of Energy.
Chile is by far the world's largest copper producer, and in the dusty towns of the Atacama, tough-looking miners are now joined at the bars by solar workers in coveralls with logos promoting "Green Power."
The region has a wildcatter feel to it. So many companies have raced to set up solar plants that they've essentially outpaced the electrical grid's ability to absorb their electricity output. At times of peak radiation in recent months, they've had to give away sun power virtually free.
Chilean officials say the problem will be overcome this year when the country's northern power grid will finally be linked to the larger central grid, which serves most of the country's residential consumers. In theory, that will allow the system to draw more heavily on sun power during the day and save sources such as hydropower and coal for the evenings, when the solar plants are useless.
Still, this remains the biggest knock on renewable energy sources: They cannot produce reliable, round-the-clock power.
Conventional plants using coal or other fuels can't be turned on and off like a light switch. So they have to keeping running during the day, when they're far less competitive, and try to make up the difference at night.
A company looking to bridge this gap in Chile is building Latin America's first solar thermal plant. You can see its solitary tower rising from the desert for miles around, like some sort of alien religious shrine. At nearly 700 feet, it is the second-tallest building in Chile.
Instead of PV panels, the solar thermal plant will have 10,000 giant, rotating mirrors set in concentric circles around the tower. They will concentrate the sun's rays on a huge boiler at the top of the tower, filled with molten salts, that reaches more than 1,000 degrees and glows like the Eye of Sauron in "The Lord of the Rings."
The superheated salts ooze downward to steam turbines at the base of the tower, retaining enough energy to generate electricity all night. It's essentially a giant, $1.4 billion rechargeable battery.
The plant's owner, Cerro Dominador, a subsidiary of U.S.-based EIG Global Energy Partners, says it will be completed in 2019. Larger solar thermal facilities based on the technology are in operation in California, and Chile has issued permits for others.
Iván Araneda, the company's top executive, said such solar thermal facilities can transform the industry.
"The attack on renewables is that they're too expensive, but this is efficient, proven technology," Araneda said. "On an even playing field, renewables can compete with anything."
Video: Chile is building Latin America's first solar thermal power plant. Here's how it works.
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