A report in The Times suggests government officials want to verify that other countries would be as interested in adopting the sophisticated technology as Tidal Lagoon executives argue.
Tidal Lagoon Power received planning consent from the government in June to construct the 320MW tidal lagoon project.
Chief executive Mark Shorrock told Utility Week the firm is “driving this process as if the has happened”.
But the Department of Energy and Climate Change (Decc) is concerned about the strength of the private investment case, given that the project’s price-tag is nearly double initial estimates.
Officials also want to check that it will produce the electricity its backers have claimed: 155,000 homes for 120 years.
A Decc spokesperson said: “Tidal Lagoon Power are seeking a significant amount of financial support from consumers for their proposed project in Swansea Bay and we need to carefully consider whether it is in the best interest of bill payers.
“At present there is no timeframe for how long the negotiation process for Swansea Bay tidal lagoon may take. It depends on a number of factors, many of which are outside the control of the government.”
The firm confirmed last month that work on building the Lagoon has been delayed to spring 2017 because the government is taking “longer than expected” to finalise a contract for difference (CfD) for the project.
The Welsh Liberal Democrats have warned there is a danger that the proposed £1 billion Swansea Bay Tidal Lagoon project will not be built following the delay on a decision.
Read Utility Week’s analysis of Swansea Bay here.