Port Hawkesbury Paper may have to jump through an extra hoop if it wants to buy renewable power from an independent producer under the province’s new retail electricity system.

The Point Tupper mill can’t be a customer in the retail market for the next four years without approval from the provincial regulator, Nova Scotia Power says. The Cape Breton operation needs the Utility and Review Board’s blessing because it has a separate power rate, the power company said in a recent regulatory filing.

“The terms of that tariff are that Port Hawkesbury Paper cannot take service under another tariff without approval of the (board),” Beverley Ware, a spokeswoman for Nova Scotia Power, said Thursday.

The so-called load-retention tariff was approved by the regulator in 2012 and is in place until Dec. 31, 2019. Under the discount power rate, the mill pays the cost of generating electricity to serve its operation. Port Hawkesbury Paper is also making a $2-million annual contribution to the fixed cost of operating the grid.

It’s not clear whether the mill, Nova Scotia’s largest power user, would ask the board for permission to purchase electricity from an alternative renewable supplier. A spokesman for Port Hawkesbury Paper couldn’t be reached Thursday for comment.

Mill officials haven’t responded to previous requests for comment on possible interest in renewable to retail.

The Liberal government passed legislation in 2012 to allow the creation of an electricity market, which fulfils a campaign promise. The system is expected to be in place next year.

The board is in the process of setting rules, procedures and tariffs for renewable producers and their customers. A hearing is slated for January.

Meanwhile, the load-retention tariff doesn’t just complicate any potential interest by the mill in the renewable market. The operation must also pay countervailing duties to the United States government, which sees the power discount as a subsidy.