Exhibit 99.1

Joint Filing Agreement

The undersigned hereby agree that the Statement on Schedule 13G dated April 28, 2021 with respect to the Units of First Reserve Sustainable Growth Corp., and any amendments thereto executed by each and any of the undersigned shall be filed on behalf of each of the undersigned pursuant to and in accordance with the provisions of Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended.

Dated: April 28, 2021

JCP Investment Partnership, LP
By:	JCP Investment Management, LLC Investment Manager
By:	/s/ James C. Pappas
	Name:	James C. Pappas
	Title:	Managing Member

JCP Investment Partners, LP
By:	JCP Investment Holdings, LLC General Partner
By:	/s/ James C. Pappas
	Name:	James C. Pappas
	Title:	Sole Member

JCP Investment Holdings, LLC
By:	/s/ James C. Pappas
	Name:	James C. Pappas
	Title:	Sole Member

JCP Investment Management, LLC
By:	/s/ James C. Pappas
	Name:	James C. Pappas
	Title:	Managing Member

/s/ James C. Pappas

James C. Pappas