Patrick Harvie has been branded “dogmatic and narrow-minded” after ruling out hydrogen boilers replacing traditional gas heating systems in his green home energy strategy.

The Scottish Government’s Carbon Zero Buildings Minister has tabled plans that would ban new homes in Scotland from having fossil fuel boilers installed from April next year.

But Mr Harvie has confirmed that hydrogen-ready boilers will be classed as “direct emissions heating systems”, and will not be an alternative to be installed.

Read more: Scottish ministers propose gas boilers ban in new buildings from 2024

Instead, the Scottish Government hopes that homeowners and developers will be encouraged to buy heat pumps or establish heating districts to replace gas boilers as part of an aim for 1 million homes to be decarbonised by 2030.

Mr Harvie, the co-leader of the Scottish Greens, has also proposed gas boilers being penalised in existing properties as part of an overhaul of energy efficiency standards.

Under the proposals, the heating system used in the property will be taken into account, with heat pumps and other systems that do not produce direct emissions set to be rewarded under the shake-up of EPC ratings.

The Scottish Government has proposed that homes meet certain standards of energy efficiency by 2033 at certain trigger points such as the sale of a home.

Read more: Gas boilers set to be penalised under energy efficiency overhaul

Concerns have been raised by Mr Harvie that hydrogen-ready boilers that do not produce a green variation of the ful, are set to emit fossil fuels for the "foressable future" as the costs for a green strand of the fuel are reduced and produced on a bigger scale.

The snub for hydrogen as a heating source comes two years after Scottish ministers called on the UK Government to “accelerate reserved decisions needed to support hydrogen blending and the wider role of hydrogen in the gas grid”.

But the UK Government has taken a similar stance to SNP and Greens ministers at Holyrood, with UK Energy Minister Grant Shapps acknowledging hydrogen is unlikely to play a role in cleaning up heating systems.

SNP ministers have committed £100m to support the green hydrogen sector.

The Scottish Government has also pointed to the fuel as a potential cash cow for a future independent Scotland, describing renewable hydrogen as potentially “Scotland’s greatest industrial opportunity since oil and gas” amid claims it could create up to 300,000 green jobs – almost double the number working in the NHS in Scotland.

But the Scottish Government’s just transition chief, Professor Jim Skea, who has taken over as chair of the United Nations’ IPCC expert panel, warned that there was no evidence the fuel could be exported overseas from Scotland.

Read more: SNP to demand UK Government accelerates hydrogen development

In response to a Holyrood question, Mr Harvie said that his new legislation “prohibits the installation of direct emissions heating systems that produce more than a negligible amount of direct greenhouse gas (GHG) emissions”.

He added: “This is to ensure that new buildings no longer contribute emissions to climate change, and do not require future retrofit to support net zero.

“Hydrocarbon gas produces more than a negligible amount of direct emissions, as demonstrated in research completed by ClimateXChange.

“Any hydrogen-ready technology is likely to operate on hydrocarbon gas for the foreseeable future.

“This means that these systems would not be permitted under the standard, as they continue to emit significant direct emissions.”

Scottish Conservative MSP, Liam Kerr, said: “This response to my question is absolutely typical of the dogmatic and narrow-minded approach of the Greens.

“Although the Scottish Government claimed that hydrogen could be a key solution in our journey to net-zero, Patrick Harvie is taking his usual inflexible position.

“It’s clear that the Scottish Greens have no interest in a realistic transition to net zero, and take no account of the costs and burdens they are heaping on ordinary people in the middle of a cost of living crisis.

"And it’s equally obvious that the SNP are doing nothing to rein in their extremist partners.”

Earlier this year, the Competitions and Marketing Authority (CMA), warned that “businesses marketing boilers as ‘hydrogen-blend’ or ‘hydrogen-ready’ risk greenwashing people into thinking these products are more environmentally friendly than they really are”.

The watchdog added that “this is despite these boilers being technically the same and emitting the same carbon emissions as standard gas boilers, because hydrogen fuel is not currently available for home heating”.

Read more: SNP's just transition chief blows hole in independence economic case

But a study by ClimateXChange, led by Scottish-based experts, found that “a 20% hydrogen blend can be safely used in domestic appliances without the need of upgrade or replacement”, potentially saving households thousands of pounds in having to rip out gas boilers for niitial use of hydrogen.

The report also says that “it is generally assumed that internal piping is also safe for use with a 20% hydrogen blend without the need for upgrade or change”.

The ClimateXChange evidence review concludes that “in many key areas, Scotland holds a leading position in the deployment of hydrogen at a large scale for heating and other uses”.

SGN is developing a “world-first hydrogen network” for 300 homes in Fife next, set to begin operating next year and use fully decarbonised green hydrogen.

In a letter to MSPs in June, Mr Harive said his proposed legislation “will prohibit the use of direct emissions heating systems (like gas boilers) in new buildings applying for a building warrant from 1 April 2024, and follow on from an initial commitment made within the Scottish Government’s 2019-20 Programme for Government”.

He added: “These regulations are a key precursor to those that will support Scotland’s existing building stock to reach net zero.

“Not only will this first step help to ensure new homes and buildings are future-proofed by removing the need for retrofit, but the regulations will ensure we avoid locking-in further harmful greenhouse gas emissions.

“The Scottish Government has undertaken extensive external engagement with a wide-range of stakeholders, including through two public consultations and an external working group, to ensure that the final regulations have the endorsement of a wide-range of stakeholders.”