There’s a reason previous governments baulked at the net zero challenge – it’s absolutely colossal, something Labour’s new Clean Power 2030 plan lays bare.

Offshore wind generating capacity, which has taken 20 years to reach 14.8GW, must more than triple to about 50GW within just six years.

The plan calls for a tripling of solar generation too, and a doubling supply from onshore wind turbines.

And to get all that clean, locally produced power to where it is actually needed will require an overhaul of the National Grid not seen since the current system was planned in the 1950s.

The government projects that to deliver all that infrastructure will require investment of £40bn a year until 2030.

Nearly all of that will come from the private sector – it hopes – knowing the Treasury certainly will not have any spare money to pay for it.

And all that is backed up by a promise that the project will lower consumer bills.

It’s a massive challenge and given the UK’s recent history of delivering large infrastructure projects – high-speed rail line anyone? – a major political gamble.

But Labour has decided it is worth the risk.

Read more:
Paris Agreement never been ‘more fragile’, UK climate chief warns
Scientists already say 2025 will be top three warmest years

If they pull it off, most analysts agree that locally generated renewable power will reduce the wholesale price of electricity – currently dictated by the international gas market.

This, in turn, will protect customers from price shocks and lower bills. Definitely a vote winner.

The other main attraction is to “get Britain building,” creating new, skilled jobs with many of them in parts of the country where they are needed most.

Coupled with that, many countries are pursuing similar goals and UK companies and workers stand to benefit by exporting their knowledge and skills.

And not forgetting the fact this government, like its predecessors, is legally required to do all this under the terms of the Climate Change Act as well as fulfilling the commitment made when we signed the global carbon-cutting Paris Agreement.

But none of that makes it any less difficult.

Take the grid for example.

Right now, as new renewable projects like large offshore windfarms are connected to our old, fossil fuel orientated national grid, on really windy days, there is already more electricity than the system can handle.

Increasingly big wind farms out to sea and a long way from consumers are having to be paid not to generate electricity, and gas-fired power stations closer to customers have to be paid to come online instead.

The bill for these “grid constraints” is already about £2bn a year.

Re-wiring the grid will solve that problem – benefitting everyone.

But imagine there’s a delay – thanks to local opposition to new pylons, or a labour shortage, or poorly managed construction – and the grid doesn’t get upgraded in step with generating capacity.

The constraint costs are projected to hit £8bn a year – that’s £80 per household – by the late 2020s.

That would make very bad headlines for a government that promised to lower bills. And the grid is just one of the pieces of the zero-carbon electricity puzzle.

Read more from Sky News:
Starmer has a particularly toxic fight to come
PM defends ‘great British institution’ of sandwiches

Everything – from reforming the retail market for energy, to smart metering, EV charging, connecting heat pumps and new technologies that can store excess electricity for when the wind isn’t blowing – will all have to happen in parallel, at pace, to ensure the project delivers the benefits promised.

The Clean Power plan will be a genuine test of whether Britain can “get building again”, but also of Keir Starmer’s political stomach when it hits the inevitable bumps along the way.