A controversial plan to build a gas-fired power plant between Hitchin and Stevenage was tonight rejected for the second time.

London-based Statera Energy Ltd proposed a 49.99MW gas-peaking electricity-generating station on Green Belt land overlooking the A602, near Little Wymondley, to satisfy peak demand for a 20-year period described as temporary.

Representatives from Wymondley and neighbouring St Ippolyts told North Herts District Council’s planning control committee, meeting at Letchworth’s Spirella Ballroom, that the plant would cause unacceptable pollution.

And district council planning officer Kate Poyser agreed with them that it would be inappropriate for the Green Belt, writing in her report that Wymondley Power Ltd had failed to justify “very special circumstances” to set aside relevant policy.

She had expressed concern in her report about evidence about levels of air and groundwater pollution, but told the meeting that following further submissions neither Environmental Health nor the Environmental Agency had objections.

The site, next to the existing Wymondley Substation off Blackmore End Road, is a former landfill created during the A602’s construction, which is now used for the grazing of horses from eight stables.

The proposed plant would have comprised 11 gas engines, each with a chimney and an array of cooling fans, with a 2½-metre security fence around the site.

This application was identical to one rejected last year apart from the shortening of the proposed stack heights to 9.2m from 15m, a revised drainage design, and the limiting of operation to 1,500 hours, or 62½ days, per year, on a rolling five-year average – rather than 2,250 hours, or almost 94 days, per year.

Wymondley parish councillor Adrian Hawkins told the committee that Statera had admitted during a public meeting that they had never built a plant like this “anywhere in the Western world”.

He said the people of Wymondley parish were concerned about air quality and that nitrogen dioxide readings at the Three Moorhens roundabout in Hitchin, about a mile from the proposed plant site, were above the maximum level set by the European Union.

Liberal Democrat councillor Sam Collins, speaking on behalf of Councillor Terry Tyler as a member advocate, said he had specialist knowledge of the technology involved due to his background in Formula 1 motor racing.

Mr Collins, who lives in St Ippolyts, urged rejection – stressing that Environmental Health had reported they wanted to restrict operating times to 1,500 hours in a year to “protect human health”.

“That’s the quote,” he said. “That gives you an idea of what is going to be coming out of those chimneys.”

Andrew Troup, speaking on behalf of Statera, said the company had built an identical plant in Yorkshire that had been operating since November last year.

“There is simply no way I would be sitting here today if I had the smallest doubt there would be any air quality issue,” he said.

“These are efficient engines, clean-burn. It would be madness for us to progress with this if we had any doubt that we would get a permit.”

He said it was “extraordinarily hard” to find suitable sites for such stations, and added: “I know nobody wants these things in their backyard, but the need is absolutely essential.”

When Labour councillor Daniel Allen asked the name of the plant in Yorkshire, Mr Troup said it was called “Creyke Beck Power Ltd”.

Conserative councillor Cathryn Henry – in whose Chesfield ward the site falls – said she felt exactly the same as when the last application was made, and moved for refusal.

The committee refused the application by a majority, with abstentions from Labour councillors Ian Mantle and Mike Hughson.