The mechanism: Section 45Z's clean fuel production credit — recently reshaped by Treasury and IRS guidance and narrowed by this year's tax legislation, which cut the maximum SAF credit from $1.75 to $1.00 per gallon and added a 2026 rule requiring North American feedstock — pays fuel producers, not airlines. To capture that subsidy, refiners need a buyer locked in for years. Airlines supply that buyer, signing offtake agreements running a decade or two, often at two-to-three-times the price of conventional jet fuel before the credit is netted in. The politics read as "Washington helps aviation go green." The cash-flow reality is that carriers are underwriting the credit risk and construction risk of unproven producers, prepaying for capacity that may never scale, at prices fixed years before delivery.