Astronomers are raising concerns as the planet’s most vital sky-observing site risks being compromised by light pollution from a proposed renewable energy initiative.
The U.S. energy firm AES Energy plans to establish a large renewable hydrogen production facility in Chile, situated just a few kilometers away from the peak of Mount Paranal, where the European Southern Observatory’s (ESO) Very Large Telescope (VLT) is located.
The VLT, which required approximately $350 million to construct in the 1990s (equivalent to $840 million today), stands as one of the globe’s most sensitive astronomical instruments, capable of scrutinizing the most fascinating entities in the cosmos. This high-precision observatory comprises four telescopes, each 27 feet (8.2 meters) in diameter, which operate collectively, and has illuminated some of the most enigmatic phenomena known to humanity. However, if the hydrogen venture, labelled INNA, moves forward, the observational capabilities of this astronomical titan will be considerably diminished, as stated by Xavier Barcons, ESO’s Director General, to Space.com.
“The luminosity of the sky will escalate by up to 10% because of this initiative,” Barcons remarked. “And that is sufficient to alter the distinction between the premier observatory in the world and a standard observational site.”
Mount Paranal, rising 8,740 feet (2,664 m) in the Atacama Desert of Northern Chile, is among the few remaining areas on Earth untainted by urban and industrial light pollution. Due to the distinct geography of the Andes mountain range, the star-filled night sky above the summit remains crystal clear for over 11 months each year, offering ideal conditions for the most rigorous astronomical investigations.
“It is the darkest location where we have ever established an observatory globally, by a significant margin,” Barcons noted.
ESO, an intergovernmental body consisting of 16 European nations, targeted Atacama more than six decades ago, having inaugurated its first observatory on La Silla mountain, south of Paranal, in 1966. Paranal became the focal point of European astronomy in the 1990s upon the construction of the VLT.
To date, the VLT has enabled astronomers to trace stellar orbits in close proximity to the black hole at the center of the Milky Way galaxy, captured the first-ever image of an exoplanet, and revealed the elusive cosmic web that stretches across the entire universe.
One key reason for the VLT’s remarkable success is the dark skies it operates in. A study released in 2023 indicated that among the 28 most powerful astronomical observatories worldwide, telescopes on Mount Paranal experienced the least levels of artificial light pollution. The superior sky-observing conditions of the region prompted ESO to select the adjacent Mount Armazones as the site for its forthcoming advanced observational giant — the Extremely Large Telescope (ELT).
Upon completion near the close of this decade, the ELT will become the largest telescope globally, studying the universe in visible light, featuring a mirror measuring 130 feet (39.3m) in width.
This telescope, valued at over $1.5 billion, is expected to enhance the scientific work conducted by the dependable VLT. It will provide even more profound insights into the most distant parts of the universe while also gathering detailed data about potentially habitable exoplanets. The anticipated light pollution from the INNA initiative could reverse all that advancement.
“We could lose the capability to observe roughly 30% of the faintest galaxies,” Barcons warned. “We are on the brink of beginning to observe details of exoplanet atmospheres, but if the sky brightens, we might not be able to detect those details anymore.”
The INNA project is a 3,021-hectare industrial area valued at $10 billion, which will include three solar farms, three wind farms, a battery energy storage system, and facilities for hydrogen production, as per Renewables Now.
ESO estimates that this complex will emit as much light pollution as a community with approximately 20,000 residents. Portions of the industrial site might come as close as 3 miles (5 kilometers) to ESO’s telescopes, and any potential future expansions would exacerbate the impact on the Paranal night sky.
Set to produce 217,023 metric tonnes of green hydrogen annually, this project poses a dilemma for ESO. The organization has pledged to minimize its carbon emissions and even constructed a 9-megawatt photovoltaic power station to provide green energy for the Paranal and Armazones observatories.
However, Barcons emphasizes that while a
project similar to INNA can effortlessly discover alternative appropriate sites, whereas for astronomers, there exists solely one Mount Paranal.
“These two elements cannot coexist in the same location. It’s just that straightforward,” remarked Barcons. “This clean hydrogen facility would be perfectly fine for us if it were located just 50 kilometers [31 miles] away. We don’t believe there’s any justification for why it couldn’t be relocated.”
AES Chile, the Chile-based branch of the AES Corporation, presented an environmental impact analysis to the Chilean Environmental Impact Agency in late December. The agency is set to carry out a public consultation prior to reaching a conclusion regarding the project. In a release issued on Dec. 30, 2024, AES Chile stated that the project is at a preliminary stage and that no investment decision has been made as of yet.
The firm also emphasized that forming a “partnership with local communities and stakeholders is a primary focus, ensuring we contribute to local economic growth while upholding the utmost environmental and safety practices.”
The corporation did not reply to Space.com’s inquiry for commentary.
ESO, in the interim, is advocating for more stringent legal safeguards for the Chilean night sky, particularly around the valuable observatories situated in the Atacama Desert. The Chilean government enacted regulations in 2023 to manage stray light emissions from external lighting to preserve the unspoiled night sky for astronomical studies. Barcons, nonetheless, asserts that additional actions are necessary.