EXHIBIT 32.1

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO SECTION 906

OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report on Form 10-K/A of Spartan Acquisition Corp. II (the “Company”) for the period ended December 31, 2020, as filed with the U.S. Securities and Exchange Commission (the “Report”), I, Geoffrey Strong, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:

(1) the Report fully complies with the requirements of Sections 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

This certificate is being furnished solely for the purposes of 18 U.S.C. Section 1350 and is not being filed as part of the Report or as a separate disclosure document.

Date: May 11, 2021

/s/ Geoffrey Strong

Geoffrey Strong

Chief Executive Officer

(Principal Executive Officer)