Overview: Maine began the process of restructuring its natural gas industry in the late 1990s. The State legislature modified the Maine Public Utilities Commission's (PUC) authority in 1998. Legislation enacted in 1999 (P.L. 1999, ch. 143) requires gas marketers to register with the PUC and authorizes the PUC to implement rules on supplier licensing and "any other subject of natural gas unbundling that requires additional regulation." On June 4, 1999, the PUC initiated a proceeding, "Inquiry into Natural Gas Competition and Unbundling Issues, Docket No. 99-342." The inquiry was suspended in late 1999, although the PUC noted in a 2001 order (Docket 2000-587) that the inquiry will be reactivated "if market conditions warrant." Unbundled (transportation-only) service is available to all commercial and industrial customers from each of the three gas utilities under its terms of service. In December 2005, the PUC approved a stipulation (Docket 2005-087) establishing 50-percent capacity assignment, non-daily metered transportation service, and triennial integrated resource plan reviews for the State's largest gas utility, Northern Utilities, Inc. (now Unitil Corp.), which serves approximately 27,000 customers in Maine. New transportation customers that had not been previous sales customers may elect capacity-exempt status.

According to the PUC’s 2009 Annual Report, over half of all deliveries made by Maine’s three natural gas utilities in 2007, excluding deliveries to electric generators, were supplied by marketers. However, the PUC noted that mandatory capacity charges, which have been in place since 2006, have made it less economical for some customers to purchase gas from a competitive supplier. As of December 2009, Maine had 37 registered retail gas suppliers. However, only a few marketers were doing business in Maine in 2009.

According to the PUC's web site, "those commercial and industrial customers who wish to purchase their commodity gas service from a competitive suppler must purchase a special meter that tracks their daily usage. For some customers, especially small customers, the cost of this “telemeter” offsets much of the potential savings from buying their commodity gas service from a competitive supplier. This requirement is being reviewed and may be modified for customers in some utility service areas, making purchases from competitive suppliers more attractive for smaller customers."