The AI Power Chain series · Part 12 of 15

Glossary of terms used

CAISO: California Independent System Operator. The grid operator for most of California.
ERCOT: Electric Reliability Council of Texas. Grid operator for most of Texas, operating largely as an electrical island.
GW: Gigawatt. One thousand megawatts of electrical power.
ISO: Independent System Operator. Regional grid operator (e.g. ERCOT, MISO, PJM, CAISO). Manages transmission access and wholesale market operations.
MISO: Midcontinent Independent System Operator. Regional grid operator covering 15 US states and Manitoba.
MV: Medium Voltage. Typically 1 kV to 35 kV. The voltage class connecting data centre power distribution to the utility grid.
PJM: PJM Interconnection LLC. Regional grid operator covering 13 US states plus DC. Includes Ohio, where the NVIDIA/OpenAI campus lands.
TAM: Total Addressable Market. The maximum revenue opportunity available if a product served every potential customer segment.

For the full corpus glossary of acronyms used across all essays, see adikumar.co/glossary.

Technical Companion · Part VI

The Modular Datacenter Stack: engineering the site

Grid interconnection queues, MV substation design, factory-test protocols, structural floor loading for 3,000-pound racks, and the water and wastewater arithmetic that governs where a 500MW campus can actually be built.

Companion to the The Modular Datacenter Stack essay (Part VI of six). Use this piece for the interconnection, protection, structural and site-engineering arguments; use the main essay for the market map, vendor structure and TAM.

Section 1: Grid interconnection queues now set the pace of AI-DC delivery, ahead of construction schedules

The published construction schedule for a hyperscale AI campus, from ground-breaking to first-power, is 18-24 months. That schedule assumes the campus already has an approved grid interconnection agreement with the local transmission operator. If it does not, the effective timeline is 4-6 years, because the queue for large-load interconnection studies is that long in most US ISOs and most European transmission areas.

A grid interconnection request for a 500MW load triggers, at minimum, a feasibility study, a system impact study, and a facilities study. Each of these takes 6-12 months of transmission-planner time. The queue for those studies is now filled with wind, solar, battery storage, industrial electrification, and increasingly, datacenter load. In PJM (the largest US ISO by capacity), the interconnection queue has grown from ~200GW in 2020 to over 1,100GW in 2025. Approval timelines have stretched from 18 months in 2015 to 4-5 years in 2025. MISO, ERCOT, ISO-NE, CAISO all show similar patterns. Europe (ENTSO-E territory) has parallel queues at national TSOs; Ireland's EirGrid moratorium on new Dublin datacenter interconnection (2022 onward) is the sharpest visible example of the constraint.

US ISO interconnection queue growth

Active interconnection queue (GW of requested generation + load), major US ISOs, 2020-2025

FERC Form 715 and Lawrence Berkeley National Laboratory interconnection queue reports (2021-2025). PJM data from PJM Queue Points reports. Approval timelines from LBNL "Queued Up" annual reports.

The datacenter siting decision that everyone underestimates. The choice of where to build a hyperscale campus turns primarily on which utility service territory has grid capacity that can be interconnected within the schedule the operator can tolerate, more than on land, tax incentives, or labour cost. Sites in slow-queue territories (PJM, CAISO, Ireland) are being deferred or downsized. Sites in fast-queue territories (ERCOT, SPP, parts of the US Southeast, Malaysia, some Middle East locations) are being oversized. The "modular" advantage in this context is that a modular MV substation can be pre-built while the interconnection study runs, and can be energised within weeks of study approval, which is a form of schedule risk arbitrage.

In brief

Prefab enclosure economics turn on skid weight, transport constraints and on-site assembly tolerances. A 5MW power skid weighs 40-60 tonnes and requires specialised transport. Interface standards for water, power and control connections at the skid boundary determine how quickly multi-vendor systems can be commissioned. The engineering choice is at that boundary.