Exhibit 31.1

CERTIFICATION

|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
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|I, Robert E.
 Swanson, certify that:
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     | 1. | I have reviewed this Annual Report on Form 10-K of the Ridgewood
 Energy S Fund, LLC;                                                                                                                                                                                                                                                          
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     | 2. | Based on my knowledge, this report does not contain any untrue
 statement of a material fact or omit to state a material fact necessary to
 make the statements made, in light of the circumstances under which such
 statements were made, not misleading with respect to the period covered by
 this report;                                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     | 3. | Based on my knowledge, the financial statements, and other financial
 information included in this report, fairly present in all material respects
 the financial condition, results of operations and cash flows of the
 registrant as of, and for, the periods presented in this report;                                                     
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     | 4. | The registrants other certifying officer(s) and I are responsible
 for establishing and maintaining disclosure controls and procedures (as
 defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control
 over financial reporting (as defined in Exchange Act Rules 13a  15(f) and
 15d  15(f)) for the registrant and have:
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 | (a) Designed such disclosure controls and procedures, or caused such
 disclosure controls and procedures to be designed under our supervision, to
 ensure that material information relating to the registrant, including its
 consolidated subsidiaries, is made known to us by others within those
 entities, particularly during the period in which this report is being
 prepared;         
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 | (b) Designed such internal control over financial reporting, or
 caused such internal control over financial reporting to be designed under
 our supervision, to provide reasonable assurance regarding the reliability of
 financial reporting and the preparation of financial statements for external
 purposes in accordance with generally accepted accounting principles;                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 | (c) Evaluated the effectiveness of the registrants disclosure
 controls and procedures and presented in this report our conclusions about the
 effectiveness of the disclosure controls and procedures, as of the end of the
 period covered by this report based on such evaluation; and                                                                                                      
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 | (d) Disclosed in this report any change in the registrants internal
 control over financial reporting that occurred during the registrants most
 recent fiscal quarter (the registrants fourth fiscal quarter in the case of
 an annual report) that has materially affected, or is reasonably likely to
 materially affect, the registrants internal control over financial
 reporting; and
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     | 5. | The registrants other certifying officer(s) and I have disclosed,
 based on our most recent evaluation of internal control over financial
 reporting, to the registrants auditors and the audit committee of the
 registrants board of directors (or persons performing the equivalent
 functions):                                         
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 | (a) All significant deficiencies and material weaknesses in the
 design or operation of internal control over financial reporting which are
 reasonably likely to adversely affect the registrants ability to record,
 process, summarize and report financial information; and                                                                                                                
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                 
|                                     |    |                                                                                                                                                                                                                                                                                                                                                 | (b) Any fraud, whether or not material, that involves management or
 other employees who have a significant role in the registrants internal
 control over financial reporting.                                                                                                                                                                                                                

| |        |  |                                        | 
| | ------ |  | -------------------------------------- | 
| | Dated: |  | March 26,
 2009                        | 
| |        |  |                                        | 
| | /s/    |  | ROBERT E.
 SWANSON                     | 
| |        |  |                                        | 
| | Name:  |  | Robert E.
 Swanson                     | 
| |        |  |                                        | 
| | Title: |  | President
 and Chief Executive Officer | 
| |        |  | (Principal
 Executive Officer)         | 

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