Glossary

Capacity & infrastructure

• MW (megawatt). A unit of power. 1 MW ≈ 750 average US homes' continuous demand. AI data centers are often described by their MW of "IT load" — the power consumed by computing equipment, not counting cooling overhead.
• GW (gigawatt). 1,000 MW. The output of a typical nuclear reactor. The biggest AI projects in construction now are 1–2 GW.
• PUE (Power Usage Effectiveness). Total facility power ÷ IT-equipment power. A perfect PUE is 1.0; modern hyperscale sites are 1.1–1.3. Lower is better; older sites are 1.7+.
• Hyperscale. Loosely: facilities with 100+ MW capacity. Sometimes used informally to mean "operated by a top-5 cloud company."
• Colocation (colo). A facility where the operator rents space, power, and cooling to multiple tenants. Common for traditional cloud, less common for AI training.
• Cooling tower. Open-loop evaporative cooling using water. High water consumption (1–5M gal/day per campus) but lower energy cost than chillers.
• Closed loop / liquid cooling. Water-glycol or dielectric fluid that circulates without evaporating. Less water use, more energy use. Required for the densest AI racks.
• Substation. The transformer yard where utility-scale voltage (138–500 kV) is stepped down to facility voltage. Often the largest single piece of new infrastructure visible at a site.

Money & finance

• Hyperscaler. Microsoft, Google, Amazon, Meta, Oracle. Companies that own and operate their own data center fleets at scale.
• REIT. Real Estate Investment Trust. The corporate form most data center landlords take. Examples: Digital Realty (DLR), Equinix (EQIX), QTS (taken private by Blackstone).
• Triple-net lease. Tenant pays rent + taxes + insurance + maintenance. The standard structure for hyperscaler ↔ landlord leases.
• IRB (Industrial Revenue Bond) / IDA (Industrial Development Agreement). The local instruments most often used to grant property-tax abatement. Read the actual document to see what was given up.
• PILOT (Payment in Lieu of Taxes). A negotiated annual payment that replaces normal property-tax assessment for the abated period.
• LDA (Lobbying Disclosure Act). The federal statute requiring quarterly lobbying reports. Senate and House LDA databases are public.

Regulation & process

• Public comment period. A formally noticed window during which any member of the public may submit written input. Common before zoning votes, environmental permits, and utility-commission decisions.
• CPCN (Certificate of Public Convenience and Necessity). What a utility needs from its state PSC/PUC to build new generation or transmission. The hearing record for a CPCN is often the most detailed public window into a project's actual energy demand.
• Categorical exclusion. A NEPA shortcut. If a federal action is judged to have no significant environmental impact, it can skip full environmental review. Some data center projects use this aggressively.
• Moratorium. A temporary suspension of permits, often used by local governments to study impacts before continuing to approve projects. Several jurisdictions have enacted 6–12-month moratoria on new data center applications.

Companies & places to know

• Project Stargate. OpenAI / SoftBank / Oracle / MGX consortium. Announced Jan 2025. Up-to-$500B over 4 years.
• Data Center Alley. Loudoun County, VA. The world's densest data-center geography; carries roughly 70% of US East Coast internet traffic.
• Colossus. xAI's Memphis supercluster. World's largest single AI training installation as of late 2024.
• Crusoe Energy. Developer that builds on-site natural-gas-powered campuses and leases them back to AI tenants. Lead developer of Stargate Abilene.