POWER OF ATTORNEY

      Known all by these presents, that the undersigned hereby constitutes and
appoints Peter Haskopoulos and Erik J. Anderson of Decarbonization Plus
Acquisition Corporation IV (the "Company") or any of them signing singly, and
with full power of substitution, the undersigned's true and lawful attorney-in-
fact to:

      1.    prepare, execute in the undersigned's name and on the undersigned's
            behalf, and submit to the U.S. Securities and Exchange Commission
            (the "SEC") a Form ID, including amendments thereto, and any other
            documents necessary or appropriate to obtain codes and passwords
            enabling the undersigned to make electronic filings with the SEC of
            reports required by Section 16(a) of the Securities Exchange Act of
            1934 (the "Exchange Act") or any rule or regulation of the SEC;

      2.    execute for and on behalf of the undersigned with respect to the
            Company, Schedules 13D and 13G and Forms 3, 4, and 5 in accordance
            with Sections 13 and 16(a) of the Exchange Act and the rules
            thereunder;

      3.    do and perform any and all acts for and on behalf of the undersigned
            which may be necessary or desirable to complete and execute any such
            Schedules 13D or 13G or Form 3, 4, or 5, complete and execute any
            amendment or amendments thereto, and timely file such form with the
            SEC and any stock exchange or similar authority; and

      4.    take any other action of any type whatsoever in connection with the
            foregoing which, in the opinion of such attorney-in-fact, may be of
            benefit to, in the best interest of, or legally required by, the
            undersigned, it being understood that the documents executed by such
            attorney-in-fact on behalf of the undersigned pursuant to this Power
            of Attorney shall be in such form and shall contain such terms and
            conditions as such attorney-in-fact may approve in such attorney-in-
            fact's discretion.

      The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary, or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be
done by virtue of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming any of the undersigned's responsibilities to comply
with Sections 13 and 16 of the Exchange Act.

      This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

      IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this tenth day of August, 2021.


                                        ERIK ANDERSON

                                        /s/ Erik Anderson
                                        ----------------------------------------
                                        Name: Erik Anderson


                                        PETER HASKOPOULOS

                                        /s/ Peter Haskopoulos
                                       ----------------------------------------
                                        Name: Peter Haskopoulos


                                        PIERRE F. LAPEYRE, JR.

                                        /s/ Pierre F. Lapeyre, Jr.
                                        ----------------------------------------
                                        Name: Pierre F. Lapeyre, Jr.


                                        DAVID M. LEUSCHEN

                                        /s/ David M. Leuschen
                                        ----------------------------------------
                                        Name: David M. Leuschen


                                        ROBERT TICHIO

                                        /s/ Robert Tichio
                                        ----------------------------------------
                                        Name: Robert Tichio


                                        JAMES AC MCDERMOTT

                                        /s/ James AC McDermott
                                        ----------------------------------------
                                        Name: James AC McDermott


                                        JEFFREY H. TEPPER

                                        /s/ Jeffrey H. Tepper
                                        ----------------------------------------
                                        Name: Jeffrey H. Tepper


                                        JENNIFER AAKER

                                        /s/ Jennifer Aaker
                                        ----------------------------------------
                                        Name: Jennifer Aaker


                                        JANE KEARNS

                                        /s/ Jane Kearns
                                        ----------------------------------------
                                        Name: Jane Kearns