Changes in Operational Carbon and Selected Infrastructure Embodied Carbon under Hourly Grid-Import Cap Stringency for a Fixed-Load Data Center

Abstract

Data centers require large and continuous electricity supply, but clean-electricity procurement is often evaluated through annual renewable matching. Annual matching is useful as a volume benchmark, yet it does not show whether clean electricity is available in the same hours as a fixed load. Existing 24/7 clean-electricity studies clarify this annual-to-hourly distinction, and data-center carbon studies emphasize the need to consider both operational and embodied carbon. However, less attention has been given to how higher hourly grid-import cap stringency shifts carbon burden between grid operation and selected clean-energy infrastructure in a fixed-load data-center pathway. This thesis evaluates that mechanism using a deterministic single-node linear optimization model based on CAISO 2022 hourly input data. The model represents a fixed 100 MW data-center load, PV and wind generation, renewable-charged 4-hour battery storage, grid imports, and model-internal curtailment. Hourly stringency is represented as a grid-import cap, and the objective minimizes modeled annual carbon within a defined accounting boundary. The carbon metric combines operational carbon from grid imports with selected PV, wind, and battery infrastructure embodied carbon. The annual benchmark shows that a 100% annual 50:50 PV/wind portfolio requires 410.641 MW of combined PV and wind capacity, or 4.106 times the fixed load. When this annual portfolio is checked hour by hour without storage or time shifting, the same-hour clean-served share is about 67.5%. This diagnostic shows that annual MWh adequacy alone does not ensure hourly feasibility for a continuous fixed load. The core alpha sweep, where alpha denotes hourly grid-import cap stringency, shows a carbon-burden shift. From alpha = 0.80 to alpha = 1.00, operational carbon decreases by 3,727.952 tCO2/year, while selected infrastructure embodied carbon increases by 13,980.540 tCO2/year. As a result, total modeled annual carbon increases by 10,252.587 tCO2/year in the base case. At alpha = 1.00, the model selects 348.415 MW of PV, 564.738 MW of wind, and 2,414.965 MWh of battery energy capacity. The resulting 913.153 MW PV/wind value is the renewable component selected jointly with battery energy capacity, not a no-battery hourly requirement. These findings show that annual MWh adequacy, same-hour feasibility, battery energy capacity, and selected infrastructure embodied carbon must be interpreted together. Within the modeled CAISO fixed-load PV/wind/4-hour-battery pathway, higher hourly grid-import cap stringency reduces grid operational carbon but can shift carbon burden to selected infrastructure.