Ammonia borane (AB) is a solid with high gravimetric and volumetric density of hydrogen that can be released at temperatures suitable for practical application as an on-board hydrogen storage material for fuel cell-powered vehicles. Hydrogen release is exothermic and exorgonic, such that it is impractical to regenerate AB from the dehydrogenated spent fuel by just an overpressure of H2. AB will need to be regenerated off board by other routes. Recent work at PNNL has shown that it is possible to digest the spent fuel with alcohol and ammonia in diglyme at room temperature to obtain a borate ester while recovering residual B-H contained in polyborazylene structures as AB. In addition to presenting these encouraging results, we will describe developments toward new routes for reducing borate esters to AB. (PNNL is operated by Battelle for the US DOE.).