ZeroTerrain — a global opportunity screen for underground pumped storage

The brief

Conventional pumped hydro — the world's dominant grid storage — needs mountains. Zero Terrain's underground approach doesn't: it puts the lower reservoir in excavated caverns, so long-duration storage can be built on flat land, near demand, almost anywhere. A 2025 report by Mike McWilliams (McWilliams Energy) argues the world needs storage on a scale we are nowhere near — on the order of 100 TWh of long-duration storage by mid-century.

The question the dashboard answers is the screening one: of every country on Earth, which both need that storage and have the ground to build it in?

The dashboard

It is a single, self-contained HTML file — no servers, no external requests, works offline, light and dark themes. The layout follows how an analyst actually screens a market: scan the world on a choropleth map, shortlist on a scatter — the ‘money chart’, need against buildability, points sized by market — then drill into any country's profile: capacity time-series with projections, its storage-versus-need gap, the score broken down into its parts, and a plain-language geology narrative.

The model

Underneath is a composite opportunity score that makes a country earn its place on both axes: Need (the storage gap, renewables growth and share, market scale) and Buildability (crystalline-basement geology and flat-terrain suitability). The two combine by geometric mean, so extreme need can't paper over missing rock — nor rock over absent need. Seismic risk, grid size and existing flexible hydro apply penalties.

Every weight and penalty is a live control: move a slider and the map, scatter and table all recompute in the browser, so the assumptions are transparent and can be pressure-tested rather than taken on trust. The data joins renewables time-series with province-level geology for around 185 countries; where a figure is missing it is shown honestly as ‘partial data’, not quietly filled in.