The reign of state Public Utilities Commission president Michael Peevey, scarred by scandals linked to a fatal explosion of natural gas in San Bruno, will soon conclude, an exit that combined with the Wednesday announcement that the PUC's executive director is also stepping down, will leave the struggling agency without its top two leaders. Peevey is due to preside over his final meeting of the five-member commission on Thursday, ending a tenure marked by his efforts to bolster green energy in California -- but tainted by evidence contained in emails that he created a culture at the regulatory agency that encouraged a cozy and accommodating relationship with utility behemoth PG&E.