<Page>

                                                                Exhibit 5.1


     [LETTERHEAD OF MORRIS, LAING, EVANS, BROCK & KENNEDY, CHARTERED]


December 12, 2001


Western Plains Energy, L.L.C.
c/o Jeff Torluemke
414 Main Street
PO Box 340
Quinter, KS 67752

Re:   Western Plains Energy, L.L.C.

Gentlemen:

We have acted as special counsel for Western Plains Energy, L.L.C., a Kansas
limited liability company (the "Company"), in connection with a Registration
Statement on Form SB-2 covering the public offering and sale of up to 3,967
Class A and Class B Capital Units of the Company (the "Capital Units"). We
are rendering this opinion in accordance with Item 601 (b) (5) of
Regulation S-B.

For purposes of this opinion, we have reviewed such questions of law and
examined such corporate records, certificates, and other documents as we have
considered necessary or appropriate for purposes of this opinion, and we have
particularly reviewed:

1.    The Amended and Restated Articles of Organization filed December 10,
2001, and Operating Agreement dated December 11, 2001.

2.    All resolutions adopted by the Board of Managers of the Company deemed
necessary and minutes or draft minutes of the meetings of the Board of
Managers deemed necessary relating to this offering.

3.    The Prospectus and the Registration Statement of which it forms a part,
to be filed with the Securities and Exchange Commission (the "Commission")
covering the offer and sale of the Capital Units; the Registration Statement
and the Prospectus as they become effective being hereinafter called the
"Registration Statement" and the "Prospectus," respectively.

In connection with our examination, we have assumed that the signatures on
all executed documents are genuine, all certified copies conform to the
originals, and all certificates containing relevant facts are correct. In
rendering our opinion we have relied upon, with their consent: (i) the
representation of the Company and its members set forth in the aforementioned

<Page>

documents as to factual matters; and (ii) certificates and assurances from
public officials as we have deemed necessary for purposes of expressing
opinions expressed herein. We have not undertaken any independent
investigation to determine or verify any information and representations made
by the Company and its members in the foregoing documents and we rely upon
such information and representations in expressing our opinion.

The opinion expressed herein shall be effective only as of the date of this
opinion letter. The opinion set forth herein is based upon existing law and
regulations, all of which are subject to change prospectively and
retroactively. Our opinion is based on the facts and the above documents as
they exist on the date of this letter, and we assume no obligation to revise
or supplement such opinion as to future changes of law or fact. This opinion
letter is limited to the matters stated herein and no opinion is to be
implied or inferred beyond the matters expressly stated herein.

Based on the foregoing, it is our opinion that:

1.   The Company has been duly organized and is validly existing as a limited
liability company in good standing under the laws of the State of Kansas. The
Company has full power and authority to own its properties and conduct its
business as currently being carried on and as described in the Registration
Statement and Prospectus.

2.   The Capital Units to be issued and sold by the Company under the
Registration Statement have been duly authorized and, when issued, delivered
and paid for in accordance with the terms of the Registration Statement, will
have been validly issued and will be fully paid and non-assessable.

We are admitted to practice law in the State of Kansas, and we express no
opinion as to the laws of any jurisdiction other than the State of Kansas and
the federal laws of the United States of America.

We hereby consent to the filing of this opinion with the Commission of as an
exhibit to the Registration Statement in accordance with the requirements of
Item 601 (b) (23) of the Regulation S-B under the Securities Act of 1933, as
amended, and to the reference to our firm therein.

Very truly yours,

/s/ Morris, Laing, Evans, Brock & Kennedy, Chartered

Morris, Laing, Evans, Brock & Kennedy, Chartered