Chile plans innovative hydroelectric power plant in world’s driest desert

Plans to build a large hydroelectricity complex in the middle of the Atacama Desert have caught the attention of many, but Chile is one of the best-placed countries in the world for highly innovative energy projects of this kind.

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An eye-catching new clean energy project is set to begin construction in one of the most unlikely of places, as a Chilean energy company plans to build a hydroelectric plant in the world’s driest desert, the Atacama. The Espejo de Tarapacá complex (Mirror of Tarapacá) will use solar energy to pump seawater from the nearby Pacific Ocean, in order to fill reservoirs which will then provide water for conventional hydroelectric generation, thus providing approximately 300 MW of clean on-demand electricity. The project, based in the Tarapacá region that lends the complex its name, earned the green light from environmental authorities in December, and is due to start construction later this year with a view to begin operation in 2020.

The project will make use of the unique natural landscape offered by Chile’s northern coastline, where the Andes mountains drop into the Pacific Ocean, often through a series of remarkably steep slopes and cliffs. The Espejo de Tarapacá will use solar pumps to draw seawater up from the Pacific to a depression, formed from ancient lakes that have long since dried out, located approximately 650m above sea level and within a few kilometres of the coastline, where the water can be stored. The water can then be drawn from the reservoir when required, in the same way as in a traditional hydroelectric dam that is fed by rivers, passing through the 300 MW generators on its way back down to the sea.

In order to do this, the system will use three ‘reversible’ turbines that act as pumps when drawing the seawater up during the day (using solar energy), and as generation turbines when the water passes through them on its way back down at night. The entire operating system – the pipelines and pump-generators – will all be situated underground.

Meanwhile, the solar energy will come from a sister project, also being planned by Valhalla, named Cielos de Tarapacá (Skies of Tarapacá). The site will use regular Solar PV panels to generate 600 MW of electricity during the day, providing power not only for the water pumps but also for local and national grids. In this way, the company will be able to provide clean renewable energy 24 hours a day: through solar power by day, and hydroelectric power by night.

Advantages over other renewable energy sources

The advantages of a project of this kind are numerous and significant. In using this unique combination of solar and hydro power, the Espejo de Tarapacá will produce a considerable amount of clean and emissions-free electricity, without the usual negative side-effects that often come with traditional hydroelectric projects derived from the damming of rivers. These include the flooding of surrounding areas, impacts on local and regional water cycles, and the major consequences for communities and ecosystems that depend on the river for their survival.

Examples of these damaging effects from around the world are rife, especially in cases where entire communities have been displaced as a result of the extensive flooding that comes with the damming and obstruction of major rivers, with the hugely controversial Belo Monte project in the Brazilian Amazon being one of the most well-known cases. In Chile alone, the Ralco complex in the southern region of Biobío, which entered operation in 2004, proved to have catastrophic impacts on local indigenous groups whose ancestral lands were submerged, and in 2014 a major project, HidroAysén, was finally shelved after years of planning due to the considerable environmental and social impacts that its construction would have implied.

However, the fact that the Espejo de Tarapacá does not involve any natural or pre-existing rivers or freshwater sources means that such impacts should be mitigated, especially given the remote and sparsely-populated nature of the arid Atacama Desert. Furthermore, Valhalla have been commended for their work to converse with local communities prior to beginning planning works for the project, ensuring that any issues or concerns were dealt with before construction begins.

Another of the Espejo de Tarapacá’s advantages stems from the fact that it uses saltwater instead of freshwater. Many of the world’s conventional hydroelectric facilities are said to be at risk from water stress due to climate change; for example, rainfall and subsequent river levels are predicted to fall within the Amazon basin if global temperature rises reach critical levels, which would compromise the capacity of the region’s numerous hydroelectric complexes. However, with the project’s close proximity to the vast Pacific Ocean, its primary resource of seawater is, in practice, unlimited and guaranteed. There is also increasing evidence that standard hydroelectric dams are not only at risk from climate change but also contribute to it – against popular wisdom – as trees and vegetation that used to stand in the extensive areas flooded for the dams’ reservoirs decay, releasing carbon dioxide and methane into the atmosphere. Once again, though, this shouldn’t be an issue in the bone-dry, vegetation-free Atacama Desert.

Finally, the Espejo de Tarapacá could help solve one of the more pressing issues related to the seemingly ‘near-perfect’ solution of meeting much of Chile’s energy demands with clean energy from abundant solar power: that of intermittency. Solar power can, by definition, only provide electricity by itself while the sun is shining, meaning that solar panels are rendered useless on cloudy days (incredibly rare though they are in the Atacama) and at night. However, by using the seawater-filled reservoirs as a form of energy storage, the project will ensure that this solar power can be ‘deployed’ at any time, without constraints.

chile ralco dam veoverde
Chile currently sources around 35% of its electricity from large hydroelectric dams, such as the Ralco dam in the south of the country, but these come with numerous environmental and social impacts. Image via VeoVerde.

Unique opportunity

While experts from Valhalla and beyond suggest that the potential for this new source of clean energy could be huge along the northern Chilean coast, there are serious doubts as to how easy it might be to copy this concept on any sort of scale around the world. Conditions in Chile, where there are steep hills and mountains sat right next to the coastline, in a highly sparsely-populated area, with almost unlimited solar resources by day to power the pumping systems, are said to be virtually unique. As Francisco Torrealba, Valhalla’s strategy manager, said: “This is the only place in the world where a project of this kind can be developed”.

Having said that, the Espejo de Tarapacá project could prove to be hugely significant in the context of Chile’s attempts to diversify its energy matrix, away from costly imported fossil fuels and conventional hydroelectricity, with all its associated problems (as listed above). At the latest count, Chile generates 11.5% of its electricity from so-called Non-Conventional Renewable Sources (ERNC by its initials in Spanish), which effectively includes all renewable sources apart from traditional hydroelectric dams. By 2025, it hopes to source at least 20% of its energy needs from these methods, and as much as 70% by 2050.

Yet with its abundant renewable resources – through the desert sun for solar power, wind power along the Pacific coast, geothermal power thanks to Chile’s status as one of the most seismically-active countries in the world, and now even seawater from the Pacific Ocean – Chile surely has the potential to make the most of this unique combination of conditions and establish itself as a renewable energy powerhouse for the region. At the very least, projects such as the Espejo de Tarapacá should consolidate Chile’s newfound position as one of the most innovative countries in the world for new ways of generating clean electricity from renewable sources.

chile solar power atacama santiago times
A PV solar panel array in Chile’s Atacama desert. With abundant sunshine, wind, geothermal resources and even the prospect of developing tidal power, Chile is well-placed to become a renewables superpower in South America. Image via the Santiago Times.

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