Why Paranal Observatory’s Future is at Risk from AES Andes'

Paranal’s strategic location in the Atacama Desert offers exceptional atmospheric stability, dry conditions, and minimal light pollution

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The European Southern Observatory’s (ESO) Paranal Observatory, nestled in the Atacama Desert of Chile, is one of the most significant astronomical sites in the world. Its unparalleled dark skies have been instrumental in groundbreaking discoveries, including the first-ever image of an exoplanet and research on the Milky Way’s supermassive black hole, contributing to the 2020 Nobel Prize in Physics. However, this invaluable scientific treasure faces a looming threat from a proposed industrial megaproject by AES Andes, a subsidiary of the U.S.-based AES Corporation.

AES’ Ambitious INNA Project

The AES Andes project, known as INNA (“Infraestructura Energética para la Generación de Hidrogeno y Amoníaco Verde”), aims to establish a massive industrial complex to produce green hydrogen and ammonia. Spanning over 7,400 acres—an area comparable to the size of Valparaíso, Chile—the project seeks to harness the region’s abundant solar and wind resources. The development plan includes constructing a port, production plants, and thousands of electricity generation units, positioning INNA as a pivotal player in advancing renewable energy.

However, its proposed location, just 3.1 to 6.8 miles from the Paranal Observatory, raises significant concerns about its environmental and scientific impact. “The proximity of the AES Andes industrial megaproject to Paranal poses a critical risk to the most pristine night skies on the planet,” warned ESO Director General Xavier Barcons.

Last month,  AES Chile submitted an Environmental Impact Assessment (EIA) for the Inna project, an early-stage industrial green hydrogen initiative supporting Chile’s National Green Hydrogen Strategy for export or domestic use.

“While this project is in early-stage development, and we have yet to make an investment decision, as part of the mandatory process to obtain the environmental permits, this EIA filing is an important step for the project to ensure its viability,” said Javier Dib, AES Chile Market Business Leader. “AES Chile is dedicated to accelerating the future of energy, creating opportunities that will diversify Chile’s energy mix, and supporting the country’s clean energy goals. As with any project, our partnership with local communities and stakeholders is a top priority, ensuring we are supporting local economic development, while maintaining the highest environmental and safety standards.”

The Environmental and Astronomical Threat

Paranal’s strategic location in the Atacama Desert offers exceptional atmospheric stability, dry conditions, and minimal light pollution—attributes that make it a unique natural laboratory for astronomical research. However, these conditions are highly sensitive to external disturbances.

Light Pollution

One of the most pressing concerns is the significant light pollution the INNA project could generate. The study “Light Pollution Indicators for All Major Astronomical Observatories” underscores the impact of even minor artificial radiance increases, which can degrade observational capabilities. Paranal’s current zenith radiance of 4.90 × 10⁻¹⁰ W/m²/sr places it among the darkest sites globally. The introduction of artificial lighting from the industrial complex risks surpassing the International Astronomical Union’s (IAU) threshold of a 10% increase in sky brightness.

This graph shows the impact of light pollution on all 28 major astronomical observatories, with ESO’s Paranal Observatory featuring as the darkest site among them. It is taken from a study by Falchi and collaborators, published in 2023 in Monthly Notices of the Royal Astronomical Society. It uses a logarithmic scale and compares the brightness directly above the observatories to the natural background brightness (1% means there is 1% more light pollution, 100% means there’s 100% more light pollution, so twice as much as without artificial sources of light). Note that some observatories appear twice: for example, Armazones, where ESO’s Extremely Large Telescope is located, has more light pollution during the construction of the telescope, when a temporary workers’ lodge is in place. This plot is a slightly adapted version of Figure 1 from the Falchi et. al study. Here, the site locations are shown in the vertical axis, with added flags, and the labels on the horizontal axis have been modified for improved readability. 
This graph shows the impact of light pollution on all 28 major astronomical observatories, with ESO’s Paranal Observatory featuring as the darkest site among them. It is taken from a study by Falchi and collaborators, published in 2023 in Monthly Notices of the Royal Astronomical Society. It uses a logarithmic scale and compares the brightness directly above the observatories to the natural …

Dust and Turbulence

Construction activities and operations within the vast complex are expected to generate significant dust emissions and atmospheric turbulence. These changes can irreparably damage the quality of astronomical observations, according to Barcons, who stated, “Dust emissions during construction, increased atmospheric turbulence, and especially light pollution will irreparably impact the capabilities for astronomical observation, which have thus far attracted multi-billion-Euro investments by the governments of the ESO Member States.”

Broader Environmental Impacts

Beyond astronomy, light pollution has profound effects on biodiversity, disrupting natural behaviors and cycles for many species. Human health is also at risk due to disturbances in circadian rhythms caused by artificial light.

A Call for Relocation

The scientific community and ESO have made it clear that relocating the INNA project is the only viable solution to protect the skies above Paranal. “Chile, and in particular Paranal, is a truly special place for astronomy—its dark skies are a natural heritage that transcends its borders and benefits all humanity,” emphasized Itziar de Gregorio, ESO’s representative in Chile. Moving the project to a less sensitive area would allow Chile to continue its leadership in renewable energy while preserving one of the last truly pristine dark skies on Earth.

Preserving a Global Treasure

Paranal Observatory represents more than just an astronomical site; it is a global asset that drives humanity’s understanding of the universe. The potential damage from the INNA project highlights the critical need for policies that prioritize the preservation of such irreplaceable scientific resources.

While the world must continue advancing renewable energy initiatives, it cannot come at the cost of losing irreplaceable natural and scientific heritage.

Environment + Energy Leader