POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

Michael L. Bennett

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ Michael L. Bennett

Michael L. Bennett

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

Singleton B. McAllister

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ Singleton B. McAllister

Singleton B. McAllister

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

Ann K. Newhall

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ Ann K. Newhall

Ann K. Newhall

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

Dean C. Oestreich

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ Dean C. Oestreich

Dean C. Oestreich

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

David A. Perdue

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ David A. Perdue

David A. Perdue

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

Judith D. Pyle

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ Judith D. Pyle

Judith D. Pyle

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

Carol P. Sanders

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ Carol P. Sanders

Carol P. Sanders

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, That I

Anthony R. Weiler

hereby constitute and appoint William D. Harvey, Eliot G. Protsch and F. J. Buri, and each of them individually, my true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for me and in my name, place and stead, in any and all capacities, to sign my name as a director of Alliant Energy Corporation (the “Company”) to the Registration Statement on Form S-8 and any amendments (including post-effective amendments) or supplements thereto relating to the securities to be offered and sold pursuant to the Alliant Energy Corporation Amended and Restated 2002 Equity Incentive Plan, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission in connection with the registration of the above-referenced Securities under the Securities Act of 1933, as amended.

        I hereby ratify and confirm all that said attorneys-in-fact and agents, or each of them, have done or shall lawfully do by virtue of this Power of Attorney.

                 WITNESS my hand this 27th day of June, 2006.

/s/ Anthony R. Weiler

Anthony R. Weiler