The fallout from the war in Iran continues and with it the ongoing pressure on British energy prices. There are only a few weeks to go before the government faces a tough set of elections across England, Scotland and Wales, with the cost-of-living crisis consistently ranking the top issue among disgruntled voters. It makes sense, then, that today the Energy Secretary, Ed Miliband, and the Chancellor, Rachel Reeves, will set out a raft of measures intended to take some of the heat off consumers’ rising bills.

Miliband’s allies argue his clean power agenda has been vindicated by the war in Iran. As Britain moves further and further towards a renewable future, it will have less and less need for fossil fuels such as the oil that has been blockaded from passing through the Strait of Hormuz. At a speech in Westminster today, hosted by the Good Growth Foundation, Miliband plans to say exactly that, declaring the “era of fossil fuels over” and arguing that the government needs to double down and go faster on clean power.

To do this, the Energy Secretary will announce a number of techy policies, focused on cleaning up the demand side (eg how we heat our homes, or drive our cars). They include: expanding the capacity for renewables on public land, cutting delays to grid upgrades and making it easier to switch to electric vehicles (EVs) and heat pumps. One (perhaps over-excited) source familiar with the proposed policies described them as “really fucking good”.

But the most consequential move is a policy set to be announced by the Chancellor on Tuesday evening. Appearing in Washington at the IMF last Thursday, Reeves hinted at her intention to announce a policy to break the link between gas and electricity prices – a major reason for high energy costs. Reeves said she and Miliband were looking into it and added, “this is something that I’ve been attracted to for quite some time”.

Later today, the Chancellor is expected to outline how the government will de-link the price of electricity from the price of gas. According to sources familiar with the matter, the government plans to do this by putting a windfall tax on so-called “old-school” renewables (those built between 2002 and 2017) in order to push them onto the fixed-price Contracts for Difference system that renewables built after 2017 are currently sold on. Under the current system, electricity produced by old-school renewables and nuclear power are sold on the same market as gas power under a “marginal pricing system”.

Under this process the wholesale price is set by whichever source is the most expensive – which is frequently natural gas. This means that if the cost of gas goes up, then the UK’s electricity costs can skyrocket. Sam Alvis, Director of Energy and Environment at the Institute for Public Policy, told the New Statesman, “the best way to stop gas influencing our electricity prices is to build enough renewables that means we barely use gas at all”, as Miliband and DESNZ are doing.

But he explained that pushing all renewables onto the same fixed-price market will de-couple the cost of electricity and gas, bringing down prices in the short term. The politics behind this decision are perhaps threefold. First, faced with a rough set of elections, in which the cost-of-living crisis is voters’ main concern, the government will be able to point to this material change as action it has taken to lower energy costs.

Second, insiders also suggest it is a way of future proofing Britain’s move to clean power from potential plans to dismantle it by a potential Reform government after 2029. Contracts for Difference – as private law contracts – are more durable and give investors more confidence that the government plans to maintain its side of the bargain. And the third calculation is perhaps that this move will neutralise a key point of difference with the Greens.

In a speech at the New Economics Foundation in March, Zack Polanski said: “We need to stop the price of gas inflating the price of electricity”. To do so, the Green Party has said it would decouple gas and electricity prices by passing emergency legislation to instruct the National Energy System Operator to act as a single buyer of power. But once the government’s plans for de-coupling gas and electricity are enacted, Labour will have got there first.

The Greens worked with the think tank Common Wealth to develop their proposal on de-coupling. They urged the government to go further. Chris Hayes, chief economist at Common Wealth, said: “Success will require high uptake, low strike prices, and meanwhile good behaviour in the balancing mechanism and rump day-ahead wholesale market. The latter question does not appear to have been addressed, which raises the stakes for the first two.” Hayes argued that “to better protect households from the Iran war, there is still a strong case for a strategic gas reserve to contain the shock and keep a lid on spark spread.” Will this persuade voters in the short term of La