Sun, wind and desert salts: Inside Chile’s renewable energy laboratory

Chile’s Atacama desert is home to the only solar thermal tower in Latin America.

The imposing 240-meter construction is one of the pillars of the country’s ambitious green energy program that began in 2019 and aims to completely replace fossil fuels by 2040.

At the same time, another project is pioneering the conversion of a coal-fired thermoelectric plant into a large storage system for renewable energy.

The high solar radiation and salts extracted from what is the driest desert on the planet are the ingredients of a powerful energy cocktail to generate and store electricity.

A renewable energy laboratory in the Atacama desert

The solar thermal Cerro Dominador, which Chileans compare to Sauron’s tower from The Lord of the Rings, has become a symbol of Chile’s energy revolution against climate change.

“A decade ago, no one would have imagined that more than a third of Chile’s energy would come from the sun and wind before 2030,” the former Environment Minister of Chile Marcelo Mena says.

“It was seen as something ambitious and it has already been surpassed.”

Today 35.4 per cent of the energy generated in Chile is wind and solar, and 37.2 per cent comes from water sources in the National Electric System (SEN), which covers the vast majority of demand.

Oil, coal and gas represent 26.9 per cent.

“Very few countries in the world have been able to truly consolidate a renewable energy industry like Chile,” says Marta Alonso, director for South America of Global Energy Services (GES), a global provider of services for the wind and solar industry.

What is a solar thermal tower?

The Cerro Dominador is one of only four solar thermal towers in the world. It is surrounded by 10,600 mirrors or heliostats that form a kind of sunflower at its feet.

Solar salts circulate through artery-like ducts that connect to the tip of the structure, where the mirrors that reflect sunlight heat them up to 565ºC.

Then, they go down those same pipes to water containers that generate steam that moves a turbine, which in turn produces electricity.

The plant has an installed capacity of 110 megawatts.

A pioneering storage system for renewable energy

Perhaps one of the biggest obstacles to decarbonisation is storage. “It’s a dilemma, because [storage] is not a developed technology yet,” says Alonso.

Chile has begun to explore an alternative. Both Cerro Dominador and the Alba Project are powered by so-called solar salts, extracted from the Atacama Desert, composed of potassium nitrate and sodium nitrate.

When melted and kept in a liquid state, they allow energy to be stored. For the Cerro Dominador tower, the salts mean it has a storage period of 17 hours.

The Alba project also aims to use the same technology to transform the modern Angamos coal-fired thermoelectric plant into a battery.

This will be supplied with photovoltaic and wind energy, which in turn will heat the salts and store power.

“The case of the Alba Project is unique in the world. It is the only project that exists of this magnitude outside of a university,” explains Diego Pardow, Chilean Minister of Energy.

As coal plants are eliminated, Chile intends to replace them with solar thermal plants or convert them into batteries like the Alba Project.