N.H. Rev. Stat. Ann. § 125-J:4-a

The department may also establish and administer a process for the registration, revocation, and enforcement of discrete emissions reductions, NOx budget allowances, and all other emissions reduction mechanisms for any air pollutants in accordance with the Clean Air Act. The use of DERs, NOx budget allowances and other emissions reduction mechanisms shall be permitted as approved by EPA and in accordance with rules adopted by the commissioner pursuant to this chapter.