GRID · FIELD GUIDE
Why the Power Grid Is Being Rebuilt — The Great Transmission Build-Out
Look at the map of planned and under-construction power lines and you'll see a grid in the middle of being rebuilt. So why now? What is driving the biggest wave of transmission-building in a generation, why does it take so long, and what are you actually looking at when you trace those dashed green lines?
Most maps of the power grid show a finished thing — the lines that exist, humming away. But the grid is not finished. Right now, all over the world, new high-voltage lines are going up: towers rising across farmland, cables being strung between mountains, undersea links being laid to bring offshore wind ashore. This map shows that work in progress — the grid being rebuilt and extended, drawn in dashed green to set it apart from the lines that already carry power.
This guide is about why that build-out is happening, and how to read it.
Why now
For most of the last century the grid grew slowly and predictably. What's happening now is different — a surge driven by three forces arriving together.
Renewable energy is in the wrong place. A coal or gas plant could be built close to the city it served. But the best wind blows offshore and across open plains, and the strongest sun falls on deserts — often hundreds of miles from where the power is needed. Tapping them means building long new high-voltage lines to carry that energy to the cities, lines the old grid simply doesn't have.
Demand is climbing again. After decades of flat electricity use in many wealthy countries, demand is rising sharply as cars, heating and industry switch from fossil fuels to electricity — and as a wave of enormous, power-hungry data centres is built to run the AI boom. More demand in new places means more lines.
The old grid is wearing out. Much of the existing network was built decades ago and was never designed to move this much power across these distances. A great deal of the build-out is simply replacing and reinforcing what's already there.
Put together, these add up to the biggest wave of transmission-building in a generation — and the dashed lines on this map are its leading edge.
From proposed to powered
A new transmission line doesn't appear overnight. It moves through a long lifecycle, and the map distinguishes two stages of it.
A line begins as a proposal — a published plan with a rough route. From there it has to be studied, environmentally assessed, granted rights-of-way across every parcel of land it crosses, and permitted by every authority along the way. Only once all of that is settled does it become an under-construction line, with towers actually going up. Eventually it's energized and joins the solid, built grid.
That pipeline matters because it's slow — often a decade or more for a major line, with the approvals taking far longer than the building. So the map draws proposed and under-construction lines differently: the under-construction corridors, near-certain to switch on, are shown brighter; the proposed ones, which may still change or fall away, sit back. You're seeing not just where the grid may grow, but how sure that growth is.
Why Europe fills the map
One thing jumps out immediately: most of these lines are in Europe. That's partly real — Europe is in a genuine, intense grid-expansion boom, racing to connect offshore wind, link national grids together, and hit climate targets. But it's also a mapping effect: European volunteers track grid projects in OpenStreetMap far more thoroughly than mappers elsewhere. So the map leans European both because that's where a lot of the building is, and because that's where the building is best recorded. Much of Asia, where major lines are also under construction, is under-represented at this tier.
What the map shows — and what it doesn't
A few honest limits. This is the planned and under-construction high-voltage grid at 300 kV and above — the same voltage tier as the built backbone, so you can toggle both and watch the existing grid in solid blue alongside the future grid in dashed green. Every line is a real feature a mapper has explicitly tagged as proposed or being built — nothing here is guessed. But coverage follows OpenStreetMap, so it's the mapped build-out, densest in Europe, not a complete global register. And plans change: a proposed line may be delayed or dropped, which is exactly why proposed and under-construction are drawn apart.
What it shows, though, is something most maps can't — not the grid as it is, but the grid as it's becoming. Open the live map and turn on both layers to see the built network and the lines reaching out to extend it.
Frequently asked questions
Why is the power grid being expanded right now?
Three forces at once. First, renewable energy: the best wind and solar resources are often far from cities — offshore, in deserts, on open plains — so connecting them needs long new high-voltage lines that didn't exist before. Second, demand is climbing fast as transport, heating and industry electrify, and as energy-hungry data centres are built. Third, much of the existing grid is decades old and was never designed to move power across these distances. Together they add up to the largest wave of transmission-building in a generation.
What's the difference between a proposed and an under-construction line?
It's how far along — and how certain — the project is. An under-construction line has steel in the ground: towers going up, contracts signed, a near-certain path to switching on. A proposed line is a real plan that has been published but may still change route, be delayed, or be cancelled before anything is built. The map draws them differently for exactly this reason — under-construction corridors are shown brighter, proposed ones sit back — so you can see not just where the grid might grow, but how sure that growth is.
How long does it take to build a transmission line?
Much longer than people expect — often a decade or more for a major line, and frequently the building is the fast part. A high-voltage line has to be planned, routed, environmentally assessed, granted rights-of-way across every landowner and jurisdiction it crosses, and permitted, all before construction starts. The physical building might take two or three years; the approvals can take ten. That long pipeline is why a map of planned and under-construction lines is a genuine window into the grid of the 2030s.
Why are new power lines so hard to build?
Because a transmission line crosses a lot of other people's land and interests. Routing one means negotiating rights-of-way with every landowner along its path, satisfying environmental rules, and often facing local opposition from communities that don't want towers near them — the familiar 'not in my back yard' problem. Lines that cross state or national borders add another layer of agencies and approvals. The engineering is rarely the bottleneck; the permitting and the politics usually are.
Is this every planned power line in the world?
No — it's the planned and under-construction high-voltage lines that have been mapped in OpenStreetMap, at 300 kV and above. Coverage follows where mappers have done that work, which is heavily weighted toward Europe (where the grid-expansion boom is also genuinely concentrated). Many real projects elsewhere, especially across Asia, aren't yet mapped at this tier. So read it as an honest picture of the mapped build-out, not a complete global register of every project.
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