Energy is the pillar most other smart city ideas quietly depend on: a traffic sensor, a charging point or a heat pump is only as "smart" as the grid feeding it. This category tracks how cities are rebuilding that grid — from meters and streetlights to solar rooftops, district heating networks and the first hydrogen pilots — and links every claim back to a real, sourced project.
Municipal energy used to mean one thing: a centralized utility pushing power one-way from a handful of large plants to passive customers. The first wave of "smart" energy, roughly from the mid-2000s, was mostly about visibility — replacing analogue meters with smart meters, and street lighting with dimmable LEDs that could be scheduled or triggered by motion. That wave alone touched enormous numbers of households, from Tokyo's TEPCO smart-meter rollout across roughly 28 million households and businesses to LED retrofits in cities as different in size as Darmstadt, Kingston and Hanoi.
The second wave, from the early 2010s onward, shifted from visibility to two-way flow: distributed rooftop and utility-scale solar, batteries, and grids that need to balance supply and demand in real time rather than just deliver it. Precisely because sun and wind don't arrive on a fixed schedule, this is also where "smart" stopped being optional — without software, a grid with lots of renewables simply doesn't balance.
Three trends define the current state of the art in this dataset. First, decentralization: instead of one utility deciding everything, cities increasingly let citizens and neighbourhoods generate and trade their own power, as in Vienna's citizen solar-trading platform, or run hybrid microgrids where the "grid" is a handful of buildings, as in the sub-Arctic microgrids of Anchorage and Yellowknife or the solar-diesel mini-grid in Kismayo. Second, sector coupling: heating, cooling and mobility are being wired into the same optimisation problem as electricity — Singapore's AI-driven district cooling and Harbin's automated district-heating network are both, underneath, energy-balancing projects wearing a different label. Third, solar at scale: from Dubai's Shams Dubai rooftop programme to Fujisawa's purpose-built solar town in Japan, utility-scale and rooftop solar have gone from pilot to default in many climates.
None of this is friction-free. Retrofit programmes compete for the same budgets as new build, ageing grids in some regions still run on manual dispatch, and the sub-Arctic and desert microgrid examples in this dataset exist precisely because a national grid connection isn't realistic there — smart energy is often a response to a hard physical constraint, not a lifestyle choice.
Batteries solve minutes-to-hours of imbalance; they don't solve the problem of storing summer sun for winter heating, or decarbonising ships, steel and heavy trucks that can't simply plug into a wall socket. That's the gap hydrogen is being tested against. This dataset currently tracks three early, very different hydrogen pilots — grouped under the Hydrogen filter — including a wind-powered e-fuel plant in Patagonia and a purpose-built hydrogen town outside Tokyo. See the dedicated Hydrogen topic guide for the full picture, including why cities specifically (rather than just industry) are where some of these pilots are landing.
Expect three things to keep moving: grids built for two-way, weather-dependent flow rather than one-way delivery; energy ownership moving closer to citizens and neighbourhoods rather than staying utility-only; and a slow, uneven build-out of hydrogen and other long-duration storage for the loads that batteries and solar alone can't cover. The project list below is a live, growing sample of where that's actually happening — not a forecast.