AI datacenter power

The $1.3 trillion power layer under the AI buildout decomposes into four real sub-markets. Each moves at a different speed, is gated by a different constraint, and is at a different stage of already being spoken for. Ranked from most open to least, with real numbers. 1. Behind-the-meter battery storage for datacenter power smoothing, most open. Size: $4.82 billion in 2026, growing to $10.23 billion by 2032 at a 13.4% CAGR (Precedence Research). GPU cluster load spikes whipsaw the grid in a way ordinary datacenter loads never did. That specific smoothing problem, distinct from grid-scale arbitrage storage, has no dominant player yet. FERC's co-location rules for behind-the-meter storage at datacenters were still being written as of 2026 (Davis Graham analysis), which is itself a signal the category is early, not mature. The gate is not capital, battery cells are a commodity, it is integration: fast-response power electronics tuned to the specific transient signature of a GPU cluster spike. A new entrant could plausibly land pilot deployments in 12-24 months. 2. On-site gas-to-power, the aeroderivative/used-turbine lane, open but narrower than it looks. Individual deals are already enormous: Chevron and Microsoft's West Texas "Project Kilby" is 2.67GW, roughly $7 billion, FID expected end of 2026, live by 2028. New heavy-frame gas turbine manufacturing (GE Vernova, Siemens Energy, Mitsubishi Power) is a captured oligopoly with backlogs stretching to 2029-2031, that reads as closed. ProEnergy's real model is the opening: buying or leasing repurposed jet-engine turbines and deploying them in 12-18 months, sidestepping the heavy-turbine backlog entirely because incumbents are turbine-supply-constrained, not EPC-constrained. The gate is securing turbine allocation, full stop. 3. SMR fleets for datacenters, looked open a year ago, reads as closed now. Over 9.8GW of committed nuclear capacity for datacenters across all signed deals (DCD / smrintel tracking). X-Energy (Amazon), Kairos Power (Google), Oklo (Equinix, Prometheus Hyperscale, Switch), plus Westinghouse's AP300 and GE Hitachi's BWRX-300, four to five named developers hold essentially every hyperscaler off-take deal that exists. First power for any current deal is 2030 at the earliest. Don't build here, this niche is effectively captured at the vendor level already. 4. Grid hardware and transformer manufacturing, the most quoted bottleneck, the least accessible. Siemens Energy's Grid Technologies backlog alone hit a record 51 billion euros (~$59B) in August 2026, up 28% year over year. The real constraint underneath the constraint: grain-oriented electrical steel, a five-company global oligopoly with structurally capped capacity. A new mill costs over $1 billion and takes four to six years to reach commercial production. Don't build here either, this is a capital-and-raw-material moat, not a market-openness one. The recommendation: behind-the-meter battery storage for datacenter power smoothing is the real opening. It is real systems engineering, not primarily capital deployment, the capital intensity is meaningfully lower than gas, nuclear, or transformers, which means it is actually startable rather than requiring a nine-figure check before day one. And it is still genuinely open, not spoken for the way SMRs already are. Second choice, if faster revenue and more capital risk is the tradeoff wanted: the gas-turbine aeroderivative EPC lane, ProEnergy has already proven the model works, the question is whether a new entrant can secure turbine allocation before the window narrows further. Confidence: the $1.3 trillion power-layer figure is McKinsey's own published split of a larger, real $7 trillion buildout estimate, medium confidence, it is a modeled projection through 2030, not a measured historical fact. The four sub-market sizes and deal figures are each independently sourced and higher confidence individually. The ranking of "how open" each sub-niche is reflects a snapshot as of August 2026, this is exactly the kind of fast-moving space where the SMR niche went from open to closed within roughly a year, so treat the ranking as time-sensitive, not permanent.