AUGUSTA, Maine (AP) A Maine official who is responsible for representing the interests of utility consumers has voiced concerns that an offshore wind electricity supply contract could add to residents’ power bills.

The developers of the offshore wind research array want Maine to approve a 20-year electricity supply contract. Backers of the proposal have described it as integral to Maine’s renewable energy goals.

Public Advocate William Harwood said this week that it’s possible the contract could increase bills if the proposed price is far above wholesale market rates, the Portland Press Herald reported on Wednesday.

Details of the contract are not publicly available yet. The developers of the project could potentially build it by 2028.

Pine Tree Offshore Wind filed papers about the project last month. That group is an affiliate of New England Aqua Ventus, which is in the process of building a demonstration turbine off Maine that would be able to power 5,000 Maine homes annually.