 BOSTON, May 14, 2021 PRNewswire -- ArcLight Clean Transition Corp. NASDAQ: ACTC ArcLight today announced that the U.S. Securities and Exchange Commission SEC has declared effective the registration statement on Form S-4 of ArcLight File No. 333-252674 as amended, the Registration Statement, which includes a definitive proxy statementprospectus in connection with ArcLights extraordinary general meeting of shareholders the Extraordinary General Meeting to consider the previously announced proposed business combination the Business Combination with Proterra Inc Proterra. 