My area of research interest could be broadly called “sustainable computing”. I maintain this page as a set of resources about sustainable computing that I find useful.
Last updated: 2021-09-23.
What is sustainable computing?
Sustainable computing concerns the consumption of computing resources in a way that means such usage has a net zero impact on the environment, a broad concept that includes energy, ecosystems, pollution and natural resources.
I consider that individual impact on the environment rounds to zero because although some people will change their behaviour, most won’t. This means that systems need to change. Energy production, transportation, manufacturing, agriculture. The transition to sustainability needs to be done on behalf of the individual by the system and at a large scale, so individuals can benefit from that change by default.
In computing, this means the organisations responsible for manufacturing components, building equipment, writing software, operating data centres, and running networks have responsibility for achieving sustainability.
Sustainability strategies in computing tend to focus on energy and the transition to renewables – the use stage. This is important, but not the only factor.
Sustainable computing therefore involves not just renewable energy, but also minimising water stress, developing policies around the right to repair and recycling of materials through a circular economy, energy efficiency of hardware and software, promoting good governance of resources, transparency, and consistent reporting.
- Estimating AWS EC2 Instances Power Consumption
This writeup explains a pragmatic approach to figuring out the energy consumption of AWS EC2 images. It uses measurements and some reverse engineering to build profiles for some common instance types, and reveals issues with relying on the SPECpower dataset (mentioned below).
I subscribe to this weekly newsletter because it provides a good summary of interesting news, events and podcasts related to what the technology sector can do to help climate change. I’m not in the Slack group though because I try and avoid group chat where possible.
Interesting sources of data related to sustainable computing:
- Cambridge Bitcoin Electricity Consumption Index
The headline figure is 97 TWh of annualised energy consumption, but with a range of 35 TWh – 364 TWh. However the missing context is how that electricity is generated. Distinguishing between whether that came from fossil fuels or renewables is important (39% renewables, primarily hydro). Whether it is possible to move to a proof-of-stake implementation, like Ethereum, is also important.
- Carbon free energy for Google Cloud regions
Google is the leader in sustainable cloud computing. They have done the most work and made the most progress at reaching carbon neutrality, then 100% renewables matching, and have a goal to hit 24/7 renewables by 2030. They are less transparent on water consumption, but do publish data on their carbon free energy percentage for each GCP region.
- SPECPower database
The Standard Performance Evaluation Corporation (SPEC) provides quarterly test results of the power and performance of the latest single and multi-node servers. By simulating workloads, this data shows the average power consumption (in watts) at 100% and idle load. The difference between the two is known as power proportionality – does the server reduce its power consumption in proportion to the load – a ratio which has been improving over time. This data is used as part of the cloud carbon coefficients project to provide estimates for the power consumption of popular cloud computing CPUs for use in the Cloud Carbon Footprint project.
Interesting academic papers related to sustainable computing:
- The environmental footprint of data centers in the United States. Environmental Research Letters. (2021)
This paper discusses the wider impact of data centres but has some major water-related findings. They show that 1/5th of direct water footprint (for cooling) comes from moderate to high stress watersheds, and that nearly half of power generation is sourced from power plants in water stressed regions. This is an important analysis showing the impact of indirect water consumption through energy generation. See also: How much water do data centers use?
- Recalibrating global data center energy-use estimates. Science. (2020)
This paper represents the current best figures of global data centre energy consumption from the perspective that energy growth has plateaued. They estimate data centres consumed 196 TWh of energy in 2020. Their system boundaries exclude cryptocurrencies and make some major assumptions about the migration to hyperscale cloud (AWS, Google, Microsoft).
- Green Cloud? Advances in Computer Science Research (2016)
This paper represents the other end of the credible data centre energy estimates, placing data centre energy consumption at 287 TWh in 2015. Their system boundaries do include crypto. See also subsequent papers from the same authors: Energy consumption of data centers worldwide (2019) and Efficiency gains are not enough: Data center energy consumption continues to rise significantly (2020) with the last of these providing an estimate for 400 TWh for 2020.
- Electricity Intensity of Internet Data Transmission: Untangling the Estimates. Journal of Industrial Ecology (2018).
This is the latest calculation of fixed-line network energy intensity i.e. the energy consumption of data transmission. The figure for 2015 is 0.06 kWh/GB with a projection that this figure will fall by 50% every 2 years. The notable aspect of this system boundary is that it excludes mobile devices.
See also my own publications.
Interesting reports related to sustainable computing:
- Clicking Clean Virginia, Greenpeace (2019)
Greenpeace are often seen as extremists but they do a good job of raising awareness. In this report they attempt to estimate energy consumption of data centers in Virginia, US, particularly those used by cloud providers like Amazon, Google and Microsoft. They use FOI requests to obtain local permits for facility sizes and then estimate the total energy demand depending on the size of the data center. The energy supplier for Virginia is notorious for using fossil fuels and so Greenpeace does a good job of laying those alongside the “100% renewable energy” claims made by the big providers. See also: How can data centers use 100% renewable electricity?
Interesting tools related to sustainable computing:
- Cloud Carbon Footprint
This is an open-source software project led by Thoughtworks that connects to your cloud billing account and runs estimates on the kWh and associated CO2 from the resources you are using. I have made several code contributions to the core project, including implementing the cloud carbon coefficients methodology as a self-contained project that is regularly updated from server power consumption test data.
- Electric Insights
Not sustainable computing specific but I use this on a regular basis to provide data about how the grid mix changes. It’s built and maintained by one of my supervisors at Imperial College London.