; or (B) used exclusively to transport people or materials to and from a commercial service airport. (31) microgrid means a localized grouping of electricity sources and loads that normally operates connected to and synchronous with the traditional centralized electrical grid, but can disconnect and function autonomously as physical or economic conditions dictate. (32) zero-emission vehicle means a zero-emission vehicle as defined in section 88.102–94 of title 40, Code of Federal Regulations, or a vehicle that produces zero exhaust emissions of any criteria pollutant (or precursor pollutant) under any possible operational modes and conditions. . (3) Special apportionment categories Section 47117(e)(1)(A) of title 49, United States Code, is amended by inserting for airport development described in section 47102(3)(P), after under section 47141, . (c) Zero-Emission program Chapter 471 of title 49, United States Code, is amended— (1) by striking section 47136; (2) by redesignating section 47136a as section 47136; and (3) in section 47136, as so redesignated, by striking subsections (a) and (b) and inserting the following: (a) In general The Secretary of Transportation may establish a pilot program under which the sponsors of not less than 10 public-use airports may use funds made available under this chapter or section 48103 for use at such airports to carry out— (1) activities associated with the acquisition, by purchase or lease, and operation of zero-emission vehicles, including removable power sources for such vehicles; and (2) the construction or modification of infrastructure to facilitate the delivery of fuel and services necessary for the use of such vehicles. (b) Eligibility A public-use airport is eligible for participation in the program if the vehicles or ground support equipment are— (1) used exclusively at the airport; or (2) used exclusively to transport people or materials to and from the airport.