A less-obvious component of workload carbon efficiency is placement and scheduling – when and where workloads are run.
A characteristic of the electricity that powers datacenter workloads is carbon intensity — the weighted average of the carbon emitted during the generation of that electricity across all generators on the grid. Carbon emissions can vary anywhere from near-zero for wind, solar, hydro, and nuclear power plants to very carbon-intensive for coal and natural gas power plants (e.g., 500 kg CO2/MWh). The mix of generators contributing electrons and the quantity generated on the local grid varies at any given time. Therefore, a grid’s carbon intensity varies over time.
For workloads that are not latency-sensitive and/or geographically restricted, the management system may determine when and/or where to run these workloads based on when and/or where the electricity is cleanest. For example, the management system can delay running a workload or run the workload in an alternate datacenter. This idea isn’t far-fetched. The share of renewables and low-carbon electricity reached almost 55% in 2019 for global electricity generation. In aggregate, workload placement and scheduling could help reduce demand for carbon-intensive electricity. In the longer term, managing datacenter workload demand could also improve the economics and stability of the electricity grid by facilitating the balance of electricity demand and supply.
