Scotland’s future electricity supplies are being put at risk due to failures by ministers to fully explore the consequences of relying on renewable energies.

The Energy Strategy Group of The Institution of Engineers in Scotland (IES) says there is a “lack of attention to engineering issues” by Westminster and Holyrood governments, and ambitious targets for achieving net zero electricity supplies to power the nation which have not been clearly thought through.

It warns that thermal power stations are being closed and confidence placed on wind and solar energy without proper safety analysis of their reliability and full consideration of what would happen to the electricity supply when the wind does not blow and the sun does not shine.

The group also says voices which dare to question the rapid switch to renewables or highlight potential risks are often shouted down by a vocal green contingent and branded ‘climate change deniers’.

The result is that a potentially constructive debate which could spotlight problem areas and suggest alternative routes to a lower carbon energy landscape, is being stifled, they say.

The IES Strategy Group insists it is not against renewable energy or the use of wind energy to feed into the National Grid. However, it warns of an urgent need to address the complex technical issues that come with inserting intermittent renewables into the nation’s power supply.

It has called for a national independent multi-disciplinary energy group including people with a range of skills and backgrounds – similar to the UK’s Covid-19 vaccine task force - to coordinate an effective plan for the nation’s future power supply.

A particular concern for the IES is the reliance on renewables to restore power in the event of a total or partial shutdown of the national electricity transmission system. Although rare, such a catastrophic situation affecting a large geographic area would require complex restoration procedures typically involving gas turbines which can operate quickly to restore power.

There are worries that a lack of suitable types of generator for such a difficult ‘black start’ situation could see towns and cities plunged into darkness for several days – raising the possibility of risks to health, and major economic and environment implications.

Iain MacLeod, of the IES, said the Westminster and Holyrood governments’ approaches are “deeply unsatisfactory” but are being replicated around the world as governments embrace renewable alternatives to fossil fuels.

Mr Macleod warned that governments are “allowing the electricity system to become increasingly unreliable”, with decisions based on what appears to be the right thing to do, rather than on reliable evidence.

“On one side we have people who believe that what needs to be done - ramp up renewables - is glaringly obvious and that carrying out studies to show that this is the way forward will hold back progress towards the goal,” he said.

“On the other side are people who believe that adding wind and solar to the system while closing down thermal stations is a very unsatisfactory strategy - that deep technical analysis of the situation is essential.

“It is like an optical illusion. Some interpret the image in one way and others see it quite differently, and it is very difficult to get your 'eye' to see the other interpretation.”

The IES, a multi-disciplinary engineering body founded in 1857, says closing reliable generation sources while increasing intermittent wind and solar generation is “pushing the system towards becoming intrinsically unreliable.”

It points to 1926, when the government decided to drive ahead with the concept of a national grid, requiring substantial investment and reorganisation of the country’s electricity systems.

The complexities of the challenge were examined by an independent group which oversaw construction and operation of the new system. The grid was created, and the cost of electricity decreased significantly.

All the UK’s 14 remaining coal-fired powered stations are due to close by 2024, while Scotland's two nuclear plants, Torness, in East Lothian, and Hunterston B, in Ayrshire, will only remain operational until 2023.

SSE Thermal and Equinor recently revealed plans to jointly develop Peterhead’s gas-fired power station as a low-carbon station, making it potentially one of the UK’s first to be equipped with carbon capture technology.

Options to support intermittent renewable energy such as carbon capture and storage, hydrogen and nuclear are being explored however, there are concerns that there is a lack of the coordination, collaboration and critical thinking that would come from an ‘engineered’ approach.

The IES suggests the introduction of renewables should be seen as a ‘safety-critical’ project similar to certain construction projects which involve several safety procedures aimed at protecting against the risk of economic, environmental and physical harm.

“There should be an independent multi-disciplinary group who would treat the electricity system as ‘safety-critical’ and use the full powers of modern technology to work out the best way forward,” Mr MacLeod added.

Energy policy is largely reserved to UK Government, however the Scottish Government works with Westminster counterparts and the National Grid, network companies and energy regulator Ofgem to promote outcomes that are consistent with its energy strategy.

The Scottish Energy Networks Strategic Leadership Group, which includes several representatives of energy businesses among its members, provides advice and recommendations concerning the move to Scotland’s net zero by 2045 target.

Cara Dalziel, Policy Manager at Scottish Renewables, said: “The Scottish Energy Networks Strategic Leadership Group, which is co-chaired by industry expert Professor Keith Bell, as well as a number of others, already oversee Scotland’s transition to the low-carbon energy system we need to replace ageing, dirty fossil fuel power stations and tackle the carbon emissions which cause climate change.

“Renewable energy projects bring economic and social benefits, and are the cheapest source of energy anywhere on the planet. Replacing old power stations with anything else simply does not make sense.

“At a UK level, renewables like wind, solar, hydro and more generate around 40% of our electricity – a tenfold increase since 2004 – and National Grid Electricity System Operator has said that by 2025 it will be able to use ‘innovative systems, products and services to ensure that the network is ready to handle 100% zero carbon’.”

A UK Government spokesperson said: “Even though we are completely committed to expanding our already world-leading renewable energy industry, we are definitely not over-reliant on these forms of energy.

"Indeed, ensuring that homes and businesses in Scotland have the certainty of secure energy supplies now and in the future is an absolute priority.

“There is broad consensus that we are seeking the right energy mix for the future and our range of energy sources – including renewables, nuclear and gas - means there is no risk of the lights going out even when the wind isn’t blowing and the sun isn’t shining."