Exhibit 10(b):

Service Agreement No. FSNG1

FIRM TRANSPORTATION SERVICE AGREEMENT

UNDER RATE SCHEDULE FT AND/OR RATE SCHEDULE FT-NN

THIS AGREEMENT, made and entered into as of this 1st day of September, 2005, by and between Southern Natural Gas Company, a Delaware corporation, hereinafter referred to as “Company”, and Alabama Gas Corporation, an Alabama corporation, hereinafter referred to as “Shipper”.

WITNESSETH

WHEREAS, Company is an interstate pipeline, as defined in Section 2(15) of the Natural Gas Policy Act of 1978 (NGPA); and

WHEREAS, Shipper has requested firm transportation pursuant to Rate Schedule FT and/or FT-NN of various supplies of gas for redelivery for Shipper’s account and has submitted to Company a request for such transportation service in compliance with Section 2 of the General Terms and Conditions applicable to such Rate Schedules; and/or

WHEREAS, Shipper may acquire, from time to time, released firm transportation capacity under Section 22 of the General Terms and Conditions of Company’s FERC Gas Tariff; and

WHEREAS, Company has agreed to provide Shipper with transportation service of such gas supplies or through such acquired capacity release in accordance with the terms and conditions of this Agreement.

NOW, THEREFORE, the parties hereto agree as follows:

ARTICLE I

TRANSPORTATION QUANTITY

1.1 Subject to the terms and provisions of this Agreement, Rate Schedule FT and/or FT-NN, as applicable, and the General Terms and Conditions thereto, Shipper agrees to deliver or cause to be delivered to Company at the Receipt Point(s) described in Exhibit A and Exhibit A-1 to this Agreement, and Company agrees to accept at such point(s) for transportation under this Agreement, an aggregate quantity of natural gas per day up to the total Transportation Demand set forth on Exhibit B hereto. Company’s obligation to accept gas on a firm basis at any Receipt Point is limited to the Receipt Points set out on Exhibit A and to the Maximum Daily Receipt Quantity (MDRQ) stated for each such Receipt Point. The sum of the MDRQ’s for the Receipt Points on Exhibit A shall not exceed the Transportation Demand.

Transportation Demand Service Agreement No. FSNG1

1.2 Subject to the terms and provisions of this Agreement, Rate Schedule FT and/or FT-NN, as a applicable, and the General Terms and Conditions thereto, Company shall deliver a thermally equivalent quantity of gas, less the applicable fuel charge as set forth in the applicable FT or FT-NN Rate Schedule, to Shipper at the Delivery Point(s) described in Exhibit B and Exhibit B-1 hereto. Company’s obligation to redeliver gas at any Delivery Point on a firm basis is limited to the Delivery Points specified on Exhibit B and to the Maximum Daily Delivery Quantity (MDDQ) stated for each such Delivery Point and in no event shall Shipper be entitled to deliveries in excess of the MDDQ such that if Shipper elects to take gas at an Exhibit B-1 Delivery Point then the MDDQ at its Exhibit B Delivery Points will be reduced proportionately. The sum of the MDDQ’s for the Delivery Points on Exhibit B shall equal the Transportation Demand.

1.3 In the event Shipper is the successful bidder on released firm transportation capacity under Section 22 of the Company’s General Terms and Conditions, Company will promptly email to Shipper the terms of the Capacity Release Transaction. Upon the issuance of the email, subject to the terms, conditions and limitations hereof and of Company’s Rate Schedules FT and FT-NN, Company agrees to provide the released firm transportation service to Shipper under Rate Schedule FT or FT-NN, the General Terms and Conditions thereto, and this Agreement.

ARTICLE II

CONDITIONS OF SERVICE

2.1 It is recognized that the transportation service hereunder is provided on a firm basis pursuant to, in accordance with and subject to the provisions of Company’s Rate Schedule FT and/or FT-NN, and the General Terms and Conditions thereto, which are contained in Company’s FERC Gas Tariff, as in effect from time to time, and which are hereby incorporated by reference. In the event of any conflict between this Agreement and the terms of the applicable Rate Schedule, the terms of the Rate Schedule shall govern as to the point of conflict. Any limitation of transportation service hereunder shall be in accordance with the priorities set out in Rate Schedule FT and/or FT-NN, as applicable, and the General Terms and Conditions thereto.

2.2 This Agreement shall be subject to all provisions of the General Terms and Conditions applicable to Company’s Rate Schedule FT and/or FT-NN as such conditions may be revised from time to time. Unless Shipper requests otherwise, Company shall provide to Shipper the filings Company makes at the Federal Energy Regulatory Commission (“Commission”) of such provisions of the General Terms and Conditions or other matters relating to Rate Schedule FT or FT-NN.

2.3 Company shall have the right to discontinue service under this Agreement in accordance with Section 15.3 of the General Terms and Conditions hereto.

2.4 The parties hereto agree that neither party shall be liab