Research in astronomy has a high carbon footprint due to several factors such as frequent air travel and high computing power needs, but the biggest carbon footprint might actually come from the construction and operation of telescopes on the ground and in space (Knödlseder et al. 2022). In this blog post, we want to highlight a major step that NSF’s NOIRLab is taking to reduce carbon emissions related to astronomical observing. NOIRLab is the national center for ground-based night-time astronomy in the USA, and is a major stakeholder in telescopes such as Gemini North and South which are operated together as the International Gemini Observatory with international partners. I want to discuss what we can learn from their example and apply to future projects.
The National Science Foundation (NSF) in the USA has recently awarded sizable new funding to NOIRLab to expand an existing PV array on Cerro Pachón (Gemini South, Vera C. Rubin Observatory) to almost 3 MW of capacity – the largest funding to date in the US astronomy community dedicated to sustainability that I know of. Coupled with an 11 MWh battery system, 100% of the electricity consumed on the mountain by Gemini South and 60% of the electricity consumed by Rubin observatory will be renewable by 2027. The full system is expected to cost $11 million dollars. Currently, Gemini South has a PV Array with about 250 kW capacity installed on the roof of the observatory building and some ground mounted PV panels right next to it (see picture). The expanded array will require significantly more space, and will be installed in a small valley just below the telescopes (see map). The Gemini and Rubin arrays will be installed and operated together in the same location; the hardware alone is expected to cost about 10 million dollars for standard glass-faced PV panels and Li-based batteries.
Chief Sustainability Officer for NOIRLab, Inger Jørgensen, points out that the expanded PV array does not only have environmental benefits, but also improves operations on the mountain as the electricity supply from the grid is not very reliable and frequent “brown-outs” require diesel backup generators. Furthermore, the new system will reduce the operating costs – an argument that convinced NSF and the international Gemini partners a few years ago to install the smaller system that’s currently in operation.
With the new battery backed array, NOIRLab/Gemini takes a different approach than ESO. ESO commissioned the Paranal-Armazones PV array with 11 MW capacity last year, which is dimensioned to power 100% of the day-time operations of the VLT and some construction need for the E-ELT. Since the VLT consists of four telescopes each comparable in size to Gemini South, the total power needed is higher. The consumption is largest during the day when the domes need to be cooled. Without batteries, ESO facilities are powered from non-renewable sources at night and do not gain the operational benefit of the more stable and quiet power supply from batteries at night. On the other hand, it saves the cost and environmental impact of battery production.
However, mountain operations are only one part of the climate impact. NOIRLab has set a goal to reduce their carbon footprint by 50% until 2027 compared to a 2019 baseline; a reduction of 43% can be achieved with measures that are already funded, which includes the PV array on Cerro Pachón described above and a number of other additional measures (see details). They also already installed PV systems that supply a fraction of the electricity needed for each facility on Gemini North, their headquarters, and their telescope base facilities; coupled with building renovations that reduce overall energy use like more efficient building heating and cooling, and a gradual switch of the fleet of cars to electric vehicles, NOIRLab is on a good track to achieve their goals.
A particular aspect that requires no investment in hardware is that NOIRLab has committed to fly less with an aim to reduce staff travel by 50%; the funds that are freed up in this way can be used to pay for further sustainability improvements. Taking all these measures will reduce NOIRLab’s annual emissions from about 12500 t CO2 equivalent / year to 6200 t CO2 equivalent / year by the end of 2027 (these estimates are for the operational carbons emissions and do not take into account embodied carbon from facility construction).
Both ESO and NOIRLab show that more sustainable operations of telescopes are possible, and importantly, it shows that these measures are cost-effective and have other positive impacts on telescope operations. While we have a long way to go to make astronomy fully sustainable, there is no reason why other telescopes should not adopt the same steps that NOIRLab is taking. In particular, PV arrays on the mountain and energy saving upgrades to offices should be uncontroversial and can actually save money in addition to being more sustainable – which might be an important argument to convince stakeholders. I hope that the positive example will help us to influence other organizations to step up and follow the lead of ESO and NOIRLab.
