A new report released this week by a Boston-based environmental group is critical of what the group calls “hidden costs” in regional electric transmission line projects.

The Acadia Center report calls on regional grid operator ISO-New England and the six states it serves to adopt four recommendations in terms of determining whether new transmission lines are needed. The recommendations are:

• Give equal consideration to local energy solutions when planning for grid reliability, and allow them to be eligible for cost recovery.

• States should adopt regulatory and market reforms to provide opportunities and financial incentives for local energy resources.

• ISO-NE should require that transmission bids be in guaranteed costs to improve the accuracy of transmission cost estimates.

• The regional grid operator should improve its energy forecasts so consumers do not pay for projects that are not needed.

William Dornbos, Acadia Center’s Connecticut director and a senior attorney with the organization, said “transmission planning and financing processes have not sufficiently evolved to enable the region to choose outcomes with the greatest consumer and environmental benefits.”

“Acadia Center is not asking to trade reliability for savings — the region is missing opportunities to ensure the lights stay on with innovative and potentially more affordable solutions,” Dornbos said.