Repository to hold scripts and tools for emissions estimates on ARCHER2, UK national supercomputing service.
| Tool | Documentation | Description |
|---|---|---|
bin/jobemissions |
jobemissions wiki page | Tool to calculate estimated Scope 2 and Scope 3 emissions for specified job on ARCHER2 |
Scope 3 emssions from the ARCHER2 hardware have been estimated from a subset of the components that are expected to make up the majority of the emissions. Note that there is a large amount of uncertainty for Scope 3 emissions due to lack of high quality Scope 3 emissions data from vendors. In particular, the number used for the compute node emissions is at the high end of estimated values and the actual value could be as much as 15% lower at around 900 kgCO2e/node.
| Component | Count | Estimated kgCO_2_e per unit | Estimated kgCO_2_e | % Total Scope 3 | References |
|---|---|---|---|---|---|
| Compute nodes | 5,860 nodes | 1,100 | 6,400,000 | 84% | (1) |
| Interconnect switches | 768 switches | 280 | 150,000 | 2% | (2) |
| Lustre HDD | 19,759,200 GB | 0.02 | 400,000 | 6% | (3) |
| Lustre SSD | 1,900,800 GB | 0.16 | 300,000 | 4% | (3) |
| NFS HDD | 3,240,000 GB | 0.02 | 70,000 | 1% | (3) |
| Total | 7,320,000 | 100% |
We then estimate the per-CU (nodeh) Scope 3 emissions by assuming a service lifetime of 6 years:
7,320,000 kgCO2e / (5,860 nodes * 6 years * 365 days * 24 hours) = 0.023 kgCO2e/CU
Tools use a value of 0.023 kgCO_2_e/CU for ARCHER2.
Scope 2 emissions from ARCHER2 are zero as the service is supplied by 100% certified renewable energy. For information purposes we can calculate what the Scope 2 emissions would have been if the energy was not 100% renewable energy using the methodology described below.
UK national grid based Scope 2 emissions are typically calculated using the compute node energy use for particular jobs along with the carbon intensity of the South Scotland region of the UK National Grid at the start time of the job. The carbon intensity is retrieved from the carbonintensity.org.uk web API.
If the energy use of a job is not available (e.g. due to counter failures) then the mean per node power draw from 1 Jan 2024 - 30 Jun 2024 on ARCHER2 is used to compute the energy consumption. This corresponds to a value of 0.41 kW per node.
Estimates of power draw of individual components of ARCHER2 suggest that the compute node power draw makes up around 85% of the system power draw.
| Component | Count | Loaded power draw per unit (kW) | Loaded power draw (kW) | % Total Scope 2 | Notes |
|---|---|---|---|---|---|
| Compute nodes | 5,860 nodes | 0.41 | 2,400 | 85% | Measured by on system counters |
| Interconnect switches | 768 switches | 0.24 | 240 | 9% | Measured by on system counters |
| Lustre storage | 5 file systems | 8 | 40 | 1% | Estimate from vendor |
| NFS storage | 4 file systems | 8 | 32 | 1% | Estimate from vendor |
| Coolant distribution units | 6 CDU | 16 | 96 | 3% | Estimate from vendor |
| Total | 2,808 | 99% |
Current Scope 2 grid based emission calculations estimates do not include overheads from the electical and cooling plant.
- IRISCAST Final Report: https://doi.org/10.5281/zenodo.7692451
- IBM z16™ multi frame 24-port Ethernet Switch Product Carbon Footprint
- Tannu and Nair, 2023: https://arxiv.org/abs/2207.10793