The SKAO’s computing needs will be met by “green computers”.
Powering the telescopes is of course only a part of a bigger picture. In the age of Big Data Astronomy, how we do big data science without big power consumption is a big question.
Here again, the SKAO has worked hard to reduce its consumption. With a current estimated consumption of 2 MW, instead of the original estimate of 6 MW, the Observatory’s two supercomputing centres will be equivalent to the world’s fastest supercomputers in 2019, but will use three times less power than current industry-standard, significantly lowering their carbon footprint.
Such stringent requirements are also driving innovation in low-power electronics, which will not only benefit the SKAO but will very likely find their way into other uses in society, contributing to lowering our global carbon footprint.
The two computing facilities, located in Cape Town, South Africa, and Perth, Western Australia, will be connected to the grid, where the share of renewables was respectively 16% and 24% in 2020. In Perth, the Pawsey Supercomputing Centre which will host the SKA-Low Science Processing Centre (SPC) is already equipped with solar panels on its roof and façade that generate 140 kW of electricity, and uses a groundwater system to reduce its electricity requirements for cooling the supercomputers.
“To offset SKAO’s emissions there, we will likely enter into what is called a wheeling arrangement,” explains A. Schutte. “Essentially, we will pay renewable energy projects elsewhere, which inject energy into the grid and help increase the share of renewables throughout the state.” This is a common approach, available to both commercial and private customers in some countries like the UK to offset their consumption.
SKAO’s Science Processing Centre (SPC) for SKA-Mid is yet to be built. Its site has been identified on the outskirts of Cape Town, and is shared with iThemba LABS, the National Research Foundation’s particle accelerator facility.
Solar panels and batteries
The current concept design proposes solar panels on the SPC’s roof with a 2.5 MW photovoltaic plant and batteries on adjacent land, which would meet a significant fraction of the SPC’s load. “Our goal is to work with SARAO to source power from a combination of an onsite generation facility incorporating solar panels, a substantial battery system and an uninterruptible power supply (UPS), with the goals of reducing the environmental footprint and to minimise the effect of load shedding events that limit the availability from the grid,” explains A. Schutte.
This hybrid system will also enable the SKAO to reduce the SPC’s power bill, with the solar panels charging the batteries, whose energy is then used during peak periods when tariffs are much more expensive, or during load shedding (also known as rolling blackout) events.
Beyond the SKAO
The SKAO’s computing needs aren’t limited to the Observatory itself. Beyond its two SPCs, the Observatory will rely on a network of SKA Regional Centres (SRCs) funded by and distributed around its member countries to store its data and serve as the interface with the international scientific community, where science data products will be processed.
Overall, some 700 PB of data will be added to the science archive every year across the SRC network, which will have a collective computing capacity of some 500 PFLOPS, or five times the world’s fastest supercomputer in 2019.
Green-computing at the exa-scale
While these facilities are outside the SKAO’s scope, there are already discussions to secure sustainable sources of power. “The Observatory’s commitment to sustainability extends to our interactions with partners,” explains Lewis Ball. “We’ve already initiated discussions with some of the prototype facilities to identify how we can work together to realise a sustainable network.”
“The member countries of the SRC Network are certainly focused on achieving the processing and storage capacity needed for the SKA telescopes in a sustainable manner. We are already engaged with several international supercomputing centres and high-performance computing providers who are progressing towards green-computing at the exa-scale,” added Prof. Peter Quinn, Chair of the SRC Steering Committee.
While power for the telescopes and computing facilities will represent the vast majority of the Observatory’s emissions, work to minimise its environmental footprint overall is an everyday challenge.
The Observatory is for instance aiming to minimise travel, a trend that has grown with the pandemic. Earlier this year, the SKAO’s Science Meeting was held virtually for the first time, enabling some 950 participants from around the world to take part, as opposed to an anticipated 300 for an in-person meeting. In total, it is estimated the entire online meeting generated just seven tonnes of CO2, compared to a single return flight from the UK to South Africa (where the meeting would have been held) which would have emitted an average of two to three tonnes of CO2, representing a reduction in emissions by more than a factor of a hundred.
Monitoring the environmental impact
“This also made the meeting more inclusive and allowed junior colleagues such as PhD students and postdocs – and those from institutions with less funding – to participate fully in our global collaboration,” adds Dr Anna Bonaldi, SKAO Project Scientist, co-organiser of the Science Meeting. Looking ahead, the SKAO will continue to look at hybrid and other forms of collaboration to maximise inclusion and sustainability but also engagement and opportunities.
In line with its recently approved environmental policy, the SKAO is also committed to monitoring and reporting on measurable environmental impacts such as CO2 emissions, water usage and waste generation. “Monitoring and reporting our environmental impact makes our emissions visible, which helps drive further improvements,” explains Lewis Ball.
Estimate of CO2 emissions
Many other small activities add up to ensure the project takes its environmental impact seriously, from the work by our South African and Australian colleagues to restore ecosystems and manage precious water resources, to funding and planting local species of trees via our outreach activities and providing electric vehicle charging points free of charge at the headquarters, thus encouraging staff to make the move to electric or hybrid vehicles.
The Observatory is also considering undertaking a comprehensive estimate of CO2 emissions across the full range of SKAO activities.
As a newly-born intergovernmental organisation, the SKAO is working to ensure its policies and processes are in line with our commitment to sustainability, and the ground-breaking science promised by this unique facility does not come at the expense of our own planet.
This article has first been published by SKAO.