; and (C) registered aircraft recycling firms eligible to purchase currently used aircraft under this section. (2) Commitment requirement In carrying out the program established under subsection (a), the Secretary shall issue such regulations as are necessary to establish requirements for an air carrier to purchase or lease an eligible aircraft described in subsection (a), including a timing requirement for the purchase of such, and decommissioning and selling of applicable currently used aircraft of the air carrier for recycling of parts or disposal, except as provided in subsection (f)(2). (d) Value of vouchers The Secretary may determine the value of each voucher, not to exceed $10,000,000, based on the difference in emissions between the currently used aircraft being decommissioned and sold and the eligible aircraft being purchased or leased. In determining the value of each voucher, the Secretary shall also consider if such eligible aircraft also include noise reduction, including whether such aircraft meet Stage 5 standards. In addition, the Secretary shall consider seat capacity and typical stage length of both the currently used aircraft being decommissioned and sold and the eligible aircraft being purchased or leased in determining the value of the voucher. (e) Regulations Not later than 180 days after the date of enactment of this Act, the Secretary shall issue such regulations as are necessary to carry out this section, including a requirement that a voucher may be used only to pay a new aircraft order, not an order placed (even if not filled) before the date of enactment of this Act. (f) Registration (1) In general The Secretary shall register aircraft recycling firms eligible to purchase currently used aircraft under this section and establish requirements and procedures for the recycling of parts or disposal of such aircraft to ensure that such aircraft are taken out of service and not used to develop other aircraft with higher greenhouse gas emissions. (2) Exception Notwithstanding paragraph (1),