def new_capacity_rule(mod, g, p):
    """
    New capacity built at project g in period p.
    Returns 0 if we can't build capacity at this project in period p.
    """
    return (
        mod.GenNewBin_Build[g, p] * mod.gen_new_bin_build_size_mw[g]
        if (g, p) in mod.GEN_NEW_BIN_VNTS
        else 0
    )