SEVERANCE AND RELEASE AGREEMENT

Exhibit 10(bb)

Execution Copy

SEVERANCE AND RELEASE AGREEMENT

This Severance and Release Agreement (the “Agreement”) is entered into between Energy Future Holdings Corp., a Texas corporation (the “Company”), and David P. Poole, an individual, (“Executive”). Executive and the Company are referred to in this Agreement as the “Parties.”

RECITALS

WHEREAS, Executive previously notified the Company of Executive’s intention to terminate his employment with the Company for Good Reason, as defined in the employment agreement between Executive and the Company dated May 1, 2004, as amended on September 28, 2007, October 4, 2007, and January 2, 2008 (“Employment Agreement”);

WHEREAS, the Company has accepted Executive’s resignation for Good Reason, and has agreed to permit Executive’s resignation for Good Reason to be effective as of March 31, 2008; and

WHEREAS, the Company and Executive desire to enter into this Agreement setting forth the terms of Executive’s separation from the Company.

NOW, THEREFORE, in consideration of the promises and mutual agreements in this Agreement, and for other good and valuable consideration, the receipt and legal sufficiency which are acknowledged, the Company and Executive agree as follows:

ARTICLE 1

RESIGNATION AND TERMINATION OF EMPLOYMENT

Effective at 12:01 a.m. on March 31, 2008 (the “Separation Date”), Executive’s employment with the Company ended, and he resigned from all positions he held as an officer of the Company and any entity that controls, is controlled by, or is under common control with the Company (an “Affiliate”).

On or before the Separation Date, Executive returned all property of the Company and its Affiliates, including all written, printed or electronic Confidential Information (as defined below), in his possession. If Executive discovers, or comes into possession of, any other Confidential Information after the Separation Date, he shall promptly return it to the Company’s General Counsel.

ARTICLE 2

SEVERANCE PAYMENT AND BENEFITS

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ARTICLE 3

WAIVER AND RELEASE

Executive represents that he has not filed any complaints of any kind whatsoever with any local, state, federal, or governmental agency or court against the Company based upon, or in any way related to, Executive’s employment with the Company. Executive further represents that he understands that payment of the severance payments and benefits as provided for in Article 2 constitute a full and complete satisfaction of any claims, asserted or unasserted, known or unknown, that Executive has or may have against the Company or an Affiliate except as provided below. In exchange for the payments to be made by the Company and benefits to be received by Executive under this Agreement, Executive individually and on behalf of Executive’s spouse, heirs, successors, and assigns hereby agrees not to sue or instigate any grievance, charge, claim, action, or suit, at law or in equity, and unconditionally releases, dismisses, and forever discharges the Company, including its predecessors, successors, parents, subsidiaries, affiliated corporations, limited liability companies and partnerships, including (but not limited to) Energy Future Holdings Corp., Energy Future Competitive Holdings Company,

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Luminant Energy Services Company, Luminant Mining Services Company, Luminant Power Services Company, EFH Corporate Services Company, TXU Retail Services Company, Texas Competitive Electric Holdings Company LLC, TXU Energy Retail Company LLC, Luminant Energy Company LLC, TXU Energy Solutions Company LLC, Oncor Electric Delivery Holdings Company LLC, Oncor Electric Delivery Company LLC, Luminant Generation Company LLC, Generation MT Company LLC, Generation SVC Company, Luminant Mining Company LLC, and all of their employee benefit plans, officers, directors, fiduciaries, employees, assigns, representatives, agents, and counsel (collectively the “Released Parties”) from any and all claims, demands, liabilities, obligations, agreements, damages, debts, and causes of action arising out of, or in any way connected with, Executive’s employment with or separation from the Company or any of the Released Parties. This waiver and release includes, but is not limited to, all claims and causes of action arising under or related to Title VII of the Civil Rights Act of 1964, as amended; the Civil Rights Act of 1991; the Civil Rights Act of 1866; Section 1981 of Title 42 of the United States Code, as amended; the Age Discrimination in Employment Act of 1967, as amended; the Americans with Disabilities Act; the Employee Retirement Income Security Act of 1974, as amended; Section 211 of the Energy Reorganization Act; the Sarbanes-Oxley Act of 2002; the Older Workers Benefit Protection Act of 1990; the Worker Adjustment and Retraining Notification Act; the Occupational Safety and Health Act, as amended; the Family and Medical Leave Act; the Texas Labor Code, including (but not limited to) Chapter 451; the Texas Commission on Human Rights Act; all state and federal statutes and regulations; all oral or written contract rights, including any rights under any Company incentive plan, program, or labor agreement; and all claims arising under common law including breach of contract, tort, or for personal injury of any sort; SAVE and EXCEPT Executive does not release Company from any liability for: (i) any claim for which Executive is entitled to indemnification under the terms of any contractual indemnity or the charter, articles, bylaws, or any other organizational documents of the Company or any of its Affiliates; (ii) any vested rights under any of the Company’s employee benefit plans; (iii) Executive’s rights under this Agreement, under the Additional Payment Agreement and under Sections 4.6, 4.7, and 5.1 of the Employment Agreement that survive Executive’s separation from employment; and (iv) Executive’s rights under any directors and officers liability insurance policies that provide coverage to Executive in his capacity as a former officer of the Company or any of its Affiliates, and nothing in this agreement is intended to or shall constitute a waiver of any such insurance coverage available to Executive.

Executive understands that this Waiver and Release precludes him from recovering any relief as a result of any lawsuit, grievance, or claim brought on his behalf and arising out of his employment or separation from employment with the Company. However, nothing in this Waiver and Release restricts Executive in any way from truthful communications with, filing a charge or complaint with, or full cooperation in the investigations of, any governmental body, entity, or agency on matters within their jurisdictions or from cooperating with the Company in any internal investigation.

The Company, on behalf of itself and its Affiliates, hereby releases, discharges and agrees to indemnify and hold harmless Executive from any and all claims and causes of action that it or they may have against Executive arising out of his employment with, or separation

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from, the Company or any Affiliate. Such release, discharge and indemnification does not include claims for violation of any law, including any securities law or willful misconduct (the Company acknowledges that it is not aware of any such conduct as of the execution of this Agreement). Company further acknowledges and agrees that, except as provided below, Executive’s sole obligations to Company from and after the Separation Date are set forth in this Agreement and that all prior agreements, whether written or oral, are terminated and of no further force and effect as of the Separation Date. Executive shall retain, and nothing in this Agreement shall affect, Executive’s rights to all indemnification and rights, including any to advancement or payment of defense and/or related legal costs, provided by a) the Company’s directors and officers liability insurance to the maximum extent provided for or permitted by the directors and officers liability insurance policy, and/or b) the Company’s or any Affiliate’s by-laws, charter, articles, organizational documents, or policies that may be applicable to Executive as a former officer of the Company or any such Affiliate.

ARTICLE 4

CONSULTATION AND REVOCATION PERIODS

Executive understands that signing this Agreement, including the Waiver and Release described in Article 3, is an important legal act. Executive acknowledges that he has consulted with legal counsel of his own choosing in connection with the matters addressed in this Agreement. Executive further acknowledges that he had twenty-one (21) days from the day he received this offer to consider this Agreement. Executive understands further that, for a period of seven (7) days following his signing of this Agreement (“Revocation Period”), he may revoke his acceptance of the offer represented by this Agreement by either delivering or mailing a written statement revoking his acceptance to the General Counsel of Energy Future Holdings Corp. at 1601 Bryan Street, 6th Floor, Dallas, Texas, 75201. In the event of such a revocation, this Agreement will not become effective, and the Company shall have no obligation to provide any rights or benefits under this Agreement (other than the Accrued Obligations described under Section 2.1.a.(i) and any other payments the Company is otherwise legally obligated to make to Executive).

ARTICLE 5

NON-DISCLOSURE, NON-DISPARAGEMENT, AND NON-SOLICITATION

“Confidential Information” means information: (i) disclosed to or known by Executive as a consequence of or through his employment with the Company or an Affiliate; (ii) not publicly available or not generally known outside the Company or its Affiliates; and (iii) that relates to the business and development of the Company or its Affiliates. Any information that does not meet each of the criteria listed in subsections (i) – (iii) above shall not constitute Confidential Information.

By way of example, Confidential Information shall include but not be limited to the following: all non-public information or trade secrets of the Company or its Affiliates that gives the Company or its Affiliates a competitive business advantage, the opportunity of obtaining such advantage, or disclosure of which might be detrimental to the interests of the Company or

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its Affiliates; information regarding the Company’s or an Affiliate’s business operations, such as financial and sales data (including budgets, forecasts, and historical financial data), operational information, plans, and strategies; business and marketing strategies and plans for various products and services; rate and regulatory strategy and plans; information regarding suppliers, consultants, employees, and contractors; technical information concerning products, equipment, services, and processes; procurement procedures; pricing and pricing techniques; information concerning past, current and prospective customers, investors, and business affiliates; plans or strategies for expansion or acquisitions; budgets; research; trading methodologies and terms; communications information; evaluations, opinions, and interpretations of information and data; marketing and merchandising techniques; electronic databases; models; specifications; computer programs; contracts; bids or proposals; technologies and methods; training methods and processes; organizational structure; personnel information; payments or rates paid to consultants or other service providers; Company files, physical or electronic documents, equipment, and proprietary data or material in whatever form including all copies of all such materials; and matters that Executive conceived or developed during his employment with the Company, as well as matters Executive learned from other employees or contractors of the Company.

Executive understands and confirms that, as a result of his employment with the Company and its Affiliates, he has obtained Confidential Information. Executive hereby reconfirms his agreement to comply with the obligations set forth in Section 4.9 of the Employment Agreement and Section II of the Company’s Code of Conduct, and hereby agrees to maintain all Confidential Information in strictest confidence. Accordingly, Executive will not: (a) use Confidential Information in any way (including, without limitation, in any future business relationship of Executive); (b) publish or disclose any Confidential Information; or (c) authorize anyone else to use, publish, or disclose any Confidential Information. Executive also agrees and acknowledges that all terms and conditions contained in this Agreement are to remain strictly confidential, and he agrees not to communicate or otherwise disclose the existence, terms, conditions, contents, or negotiations relating to this Agreement to any person or entity other than his spouse, financial advisor, tax advisor, attorney, accountant or any governmental entity that requests such information in any manner, whether directly or indirectly, without prior written consent from the Company authorizing the particular disclosure requested; such consent by the Company shall not be unreasonably withheld. Any authorized disclosure to Executive’s spouse, financial advisor, tax advisor, attorney or accountant shall be accompanied by an instruction that the Agreement and related information remain confidential. Executive agrees to provide the Company written notice of any request by a governmental entity for information relating to this Agreement in advance of providing such information to a governmental entity.

The Parties shall not make, repeat, or publish to any third party any false, disparaging, defamatory, accusatory, or derogatory remarks or references about one another, whether oral or in writing, concerning the other Party or any of the Released Parties, or otherwise take any such action that might reasonably be expected to cause damage or harm to the other Party or any of the Released Parties, provided however that this Section 5.2 shall not apply to statements made by or about any affiliates (other than the Company, its direct parent company, and its subsidiaries) of Kohlberg Kravis Roberts & Co. LP, TPG Capital LP, Goldman Sachs & Co. or any future owner of the Company. The Company’s obligations under this Paragraph are limited

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to only those individuals who are Executive Officers (as defined in Rule 16a-1(f) of the Securities Exchange Act of 1934, as amended) at the time of the Separation Date and who are acting in their capacity as Executive Officers of the Company at the time they make a remark or reference that allegedly violates this Paragraph. This Paragraph does not prohibit either Party from making truthful statements regarding the other Party or any of the Released Parties while cooperating with a governmental investigation or testifying under oath. Executive acknowledges that he is making, after the opportunity to confer with counsel, a knowing, voluntary, and intelligent waiver of rights Executive may have to make disparaging comments regarding the Company, including rights under the First Amendment to the United States Constitution and any other applicable federal and state constitutional rights. For the avoidance of doubt, nothing contained in this Section 5.2 shall be deemed to restrict Executive from competing against the Company or representing competitors of the Company in a legal or other fiduciary capacity.

Executive hereby reconfirms his agreement in Section 4.10 of the Employment Agreement that he shall not, for the one (1) year period following the Separation Date, directly or knowingly indirectly, either as an employee, employer, independent contractor, consultant, agent, principal, partner, stockholder, officer, director, or in any other individual or representative capacity, either for his own benefit or the benefit of any other person or entity: (a) solicit, induce, encourage, or in any way cause any of the Company’s or an Affiliate’s customers or prospective customers, or any person, firm, corporation, company, partnership, association, or entity which was contacted or whose business was solicited, serviced, or maintained by the Company or an Affiliate during the term of Executive’s employment with the Company, to reduce or terminate its business relationship with the Company or such Affiliate; or (b) solicit, recruit, induce, encourage, or in any way cause any employee of the Company or an Affiliate to terminate his or her employment with the Company or such Affiliate; provided that the prohibition described in this clause (b) shall not apply to Executive’s professional assistant, C. Wood, and the paralegal primarily assigned to Executive at the time of Executive’s cessation of employment with the Company, C. Duran.

Executive agree that a breach of this Article 5 would cause immediate and irreparable loss, damage, and injury to the Company; that damages for such a breach would be exceedingly difficult, if not impossible, to estimate; and that the Company would have no adequate remedy at law. Accordingly, Executive acknowledges and agrees that injunctive relief would be appropriate relief for such breach and to prevent further breaches of this Article.

ARTICLE 6

MISCELLANEOUS

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If any term, provision, covenant, or restriction of this Agreement is held by a court of competent jurisdiction to be invalid, void, or unenforceable, the remainder of this Agreement and the other terms, provisions, covenants, and restrictions hereof shall remain in full force and effect; they shall in no way be affected, impaired, or invalidated. It is hereby stipulated and declared to be the intention of the Parties that they would have executed this Agreement had the terms, provisions, covenants, and restrictions that may be hereafter declared invalid, void, or unenforceable not been initially included.

The Parties agree that the covenants and agreements set forth in Articles 2, 3 and 5, and Sections 6.1.a., 6.3, and 6.6 of this Agreement are of a continuing nature, and they shall survive the expiration, termination, or cancellation of this Agreement, unless such Articles are specifically extinguished, terminated, or cancelled in a writing signed by both Parties and identified as an amendment to this Agreement. The Additional Payment Agreement shall also survive the expiration, termination, or cancellation of this Agreement unless it is specifically extinguished, terminated, or cancelled in a writing signed by both Parties.

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This Agreement is personal between the Company and Executive. Executive may not sell, assign, or transfer any rights or interests created under this Agreement, or delegate any of his duties, without the prior written consent of the Company. The Company may, without Executive’s consent, assign this Agreement and its rights, benefits, and obligations hereunder to any of its Affiliates or a successor entity. In the event of an assignment by the Company to an Affiliate, the Company will fully and unconditionally guarantee any obligations to Executive arising from this Agreement.

The Parties agree to perform any further acts and to execute and deliver any further documents which may be necessary or appropriate to carry out the purposes of this Agreement.

This Agreement shall be governed by, and construed and enforced in accordance with, the laws of the State of Texas, regardless of choice-of-law principles. Each party submits to the jurisdiction of the courts in Dallas County, Texas, and the Parties agree that the proper venue and jurisdiction for any cause of action relating to this Agreement (whether sounding in tort or contract) shall be in Dallas County, Texas. In the event any issue arising out of this Agreement is litigated by the Parties, the prevailing party shall be entitled to recover from the other party its reasonable attorneys’ fees and costs.

All notices from one party to the other shall be deemed to have been duly delivered when hand delivered or sent by United States certified mail, return receipt requested, postage prepaid, as follows:

The failure of either Party to enforce or require timely compliance with any term or provision of this Agreement shall not be deemed to be a waiver or relinquishment of rights or obligations arising hereunder, nor shall any such failure preclude the enforcement of any term or provision or avoid the liability for any breach of this Agreement.

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This Agreement constitutes the entire agreement between the Parties hereto with respect to the subject matter of this Agreement. Except where specifically referenced otherwise in this Agreement, it supersedes and replaces any and all prior or contemporaneous negotiations, undertakings, understandings, or agreements (whether written or oral) of any kind between Executive and the Company with respect to the terms of Executive’s separation from the Company and its Affiliates.

I HAVE READ THIS AGREEMENT AND FULLY UNDERSTAND ALL ITS TERMS AND WHAT THEY MEAN. NO OTHER PROMISE, INDUCEMENT, THREAT, AGREEMENT, OR UNDERSTANDING OF ANY KIND OR DESCRIPTION WHATSOEVER HAS BEEN MADE WITH OR TO ME TO CAUSE ME TO SIGN THIS AGREEMENT. I ENTER INTO AND SIGN THIS AGREEMENT KNOWINGLY AND VOLUNTARILY, WITHOUT DURESS OR COERCION OF ANY KIND WHATSOEVER, AND WITH THE INTENT OF BEING LEGALLY BOUND BY THIS AGREEMENT.

IN WITNESS WHEREOF, the Parties execute this Agreement as follows:

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