Japan's Eight Major Utilities to Build or Expand 30 Substations to Meet AI Demand
Taylor Wilson
Japan's eight major power companies plan to build or expand 30 substations nationwide, targeting roughly 15 GW of total transmission capacity by the early 2030s — a direct response to forecasts that data-center power demand will grow tenfold by 2035, with grid expansion already running at more than double the projected demand pace.
How much more power do data centers actually need?
OCCTO, Japan's cross-regional grid coordinator, projects data-center power demand will surge from 640 MW in fiscal 2026 to 6,610 MW in fiscal 2035 — roughly a tenfold increase in a decade.
This means → AI is not just compute-hungry; it is power-hungry. Data centers are becoming the single largest new load on Japan's grid.
The utilities' response: build capacity at more than twice the forecast demand growth rate — lay the infrastructure first, let tech companies move in after.
Where are the 30 substations going?
TEPCO Power Grid will expand nine substations by 2029, covering data-center clusters in Inzai (Chiba) and Saitama.
Kansai Transmission & Distribution is expanding substations in Kobe and Osaka; KDDI opened a new data center in Sakai, Osaka (a former Sharp factory site) in January, and SoftBank is building on the same site.
The plan spans 18 prefectures, well beyond Tokyo and Osaka — Hokkaido Electric will build three new substations by 2031; Kyushu Electric is expanding in Kumamoto to support the local semiconductor cluster.
In plain terms = the grid is no longer just following big cities. It is following data centers and chip fabs into "non-core" regions like Hokkaido and Kyushu.
Who pays for all of this?
The utilities have not disclosed project-level costs, but estimated annual investment for the nationwide transmission and distribution network — substations included — runs at roughly ¥4.8 trillion.
TEPCO Power Grid expects to invest about ¥1.6 trillion per year through fiscal 2027 on substation upgrades and related work; Kansai Transmission & Distribution estimates about ¥830 billion per year.
This means → these costs will ultimately be passed through to consumer electricity bills — upward pressure on rates for Japanese households and businesses.
Does this actually fix the bottleneck?
Connecting a data center to the transmission grid currently takes up to about ten years in some cases — the single biggest constraint on investment.
Whether this wave of substation construction can meaningfully shorten that lead time is the real test of its effectiveness.
In plain terms = building substations is not the same as solving the problem. If the wait from application to power-on still stretches close to a decade, data centers will remain stuck at the last mile.
Content is for reference only, not financial advice.