POWER OF ATTORNEY


Know all by these present that the undersigned hereby constitutes
and appoints Paul J. Kaleta, Michael Eason and Miceala J. Decker,
and each of them collectively or individually, as his or her true
and lawful attorney-in-fact to:

(1) execute for and on behalf of the undersigned, Forms 3, 4, and
5 in accordance with Section 16(a) of the Securities Exchange Act
of 1934 and the rules thereunder;

(2) do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to complete the
execution of any such Forms 3, 4 or 5 and timely filings of such
forms with the United States Securities and Exchange Commission
and any other authority; and

(3) 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 his
discretion.

The undersigned hereby grants to such attorney-in-fact full power
and authority to do and perform all and every act and thing whatsoever
requisite, necessary and proper to be done in the exercise of any of
the rights and powers herein granted, as fully to all intents and
purposes as such attorney-in-fact 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 his
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 attorney-in-fact, in
serving in such capacity at the request of the undersigned, is not
assuming any of the undersigned's responsibilities to comply with
Section 16 of the Securities Exchange Act of 1934.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of the 2nd day of January, 2012.

/s/Paul J. Kaleta