Imperial College London (ICL) researchers have urged caution to those basing future energy decisions on “over-optimistic models that predict that the entire system could be run on renewables by the middle of this century.”

While the proportion of renewable energy is increasing every year, (renewables’ share of electricity generation was 30 per cent in 2017 Q3, up 4.6 percentage points on the share in 2016 Q3) the amount it will increase by 2050 has been much debated.

The new paper published by ICL said many renewable energy models fail to consider the reliability of supply. Models that did not consider power transmission, energy storage and system operability requirements were particularly criticised.

Its authors, Clara Heuberger and Niall Mac Dowell, said that some studies and models used to predict how whole energy systems may run on near-100 per cent renewable energy by 2050 may not take into account what they described as “real-world challenges”.

One model the pair tested, which used a UK power generation system that is forecasted to be based entirely on hydro, wind and solar stations by 2050, failed enough to deem it “inoperable”, due to the lack of firm and dispatchable “back-up” energy systems.

The team found even if they added a small amount of backup nuclear and biomass energy, creating a 77 per cent wind, water and sunlight (WWS) system, around 9 per cent of the annual UK demand could remain unmet, leading to considerable power outages and economic damage.

The study concluded the focus should be on maximising the rate of decarbonisation, rather than on the exclusive use of renewable power.

“These system transitions must be socially viable, said Mac Dowell. “If a specific scenario relies on a combination of hypothetical and potentially socially challenging adaptation measures, in addition to disruptive technology breakthroughs, this begins to feel like wishful thinking.”

Most power sector decarbonisation models already take a whole systems approach. The government’s own model is famously enforced by the Climate Change Act, which sets emissions targets rather than renewable energy or technology-specific goals.

The Committee on Climate Change also does not model for any particular technologies and merely advocates on whole sector emission guidelines, technology deployment costs and the need for system flexibility.

Elsewhere last month, Ikea launched a collective energy switch that promises a 100 per cent renewable electricity tariff.

The Swedish furniture retailer has joined forces with the Big Clean Switch campaign to use a collective switch to secure cheaper green power for households. The two companies claim it will save a typical UK household £300 a year.