def startup_fuel_burn_rule(mod, g, tmp):
    """
    Startup fuel burn is applied in each timepoint based on the amount of
    capacity (in MW) that is started up in that timepoint and the startup
    fuel parameter.
    """
    return mod.GenCommitCap_Startup_MW[g, tmp] \
        * mod.startup_fuel_mmbtu_per_mw[g]