Campaigners against the scheme say the public consultation used to pick the £300m design was flawed.
And last night council chief Richard Williams issued a new plea to developers to consider alternative sites for the scheme.
He said there are other locations where the giant facility, set to be built at Southampton docks, could be placed.
Three options were put to the public during the summer, and the company says that 52 per cent of respondents chose the “marine” look.
But campaigners have dismissed the statistic – saying that many people put “none of the above” on the design consultation and these results have not been included.
Helius has refused to comment on how many people took part in the survey.
Meanwhile Cllr Williams has asked the company to come to a meeting to discuss other places the plant could be built – but says he cannot reveal alternative locations at this stage.
He said: “This is an open invitation to Helius – let’s explore an alternative way forward.
“I couldn’t possibly comment on where those locations are – but let’s just say it’s not an idle promise.
“I have been looking at this at a strategic level for quite some time.
“We want them to pause just for a week or two before they do anything final, come and talk to me and at least listen to what I have to say.”
Helius say they are happy to meet with the council – but they are unaware of other suitable sites in the area.
Planning director Paul Brighton said: “The company has undertaken a nationwide search for suitable sites for Biomass energy projects.
“This has included a comprehensive assessment of potential sites in the Southampton area – the proposed location in the Western Docks was selected as it met the minimum critical requirements for the scheme.
“To date, the alternative sites suggested have been either unavailable or have characteristics which are unsuitable for a proposed biomass fuelled energy scheme.”
Protesters against the plant have also said they are not only against the location, but also the principle of the plans.
No to Southampton Biomass campaigner and Regents Park resident Steven Galton said: “The problem is with something this size, there’s never going to be a right place to put it.
“I’m against the industrial size biomass because it’s not green – you’re just putting more greenhouse gases into the atmosphere.”
A referendum on the plans was scrapped by civic chiefs after costs spiralled from an initial £5,000 to £75,000.
Helius say they will now work on adding more detail to the “marine”
design, ahead of submitting a planning application to the National Infrastructure Directorate of the Planning Inspectorate later this year.
They say that 450 jobs will be created building the project which will have 40 permanent staff.
Once the application is accepted, the public will be able to register as “interested parties” to make comments on the scheme, before a final decision is made by the Secretary of State for Energy and Climate Change – currently Liberal Democrat Ed Davey.