PG&E is exploring the potential development of a Compressed Air Energy Storage (CAES) project and is issuing this Request for Offers (RFO) per the Department of Energy's (DOE) Smart Grid DemonstrationProgram. In addition to the DOE, the CAES project has received funding from the California Energy Commission and the California Public Utilities Commission.

PG&E is issuing this RFO to (1) potentially procure products and services related to the CAES project, and (2) determine the technical and economic feasibility of energy storage using compressed air in a depleted natural gas reservoir.

The proposed CAES project would use energy to compress air and inject it into a depleted natural gas reservoir in a porous rock formation, approximately one half to one mile underground. When electricity is needed, the compressed air would be released, heated using natural gas, and expanded in an expansion turbine that powers a generator.

A nearly depleted natural gas field in San Joaquin County, California has been selected for the project site and subjected to an air injection/withdrawal test. Specific findings on geology, preliminary engineering, environmental analysis, and other information that PG&E has gathered through testing and analyses for the site will be available for all qualified RFO participants in a virtual data room. If constructed, PG&E anticipates the project would be between 100 and 350 MW, and would be required to have a minimum duration of 4 hours.

PG&E is seeking to purchase, based on agreement type, energy, capacity, ancillary services, and, as applicable, renewable and environmental attributes, and any other benefits ("Products") from a new Energy Conversion Facility to be designed, constructed, operated, and maintained by Participant that utilizes the San Joaquin site, or another site obtained by the Participant. The Agreement options are located in the "2015 CAES RFO Protocol and Appendices" section below and identified by Appendices E1, E2 and E3.

All deadlines close at 5:00 P.M. Pacific Prevailing Time ("PPT"), unless otherwise noted.

Get additional information on this project and learn about the PG&E commitment to expanding renewable energy sources and storage technologies. Visit Compressed Air Energy Storage.

PG&E's schedule for CAES


PG&E issues the CAES RFO

October 9, 2015

Signed Confidentiality Agreements (Appendix 1) and Experience and Qualifications responses (Appendix 2) accepted from Participants. All requests for access to the electronic Data Room must be received no later than 1:00 P.M. PPT on April 13, 2016.

October 9, 2015 - April 13, 2016

Data Room available to Participants who have submitted Appendix 1 and 2, and who have been approved by PG&E

October 16, 2015

Deadline to submit registration for General Participants' Webinar

October 26, 2015

General Participants' Webinar

October 29, 2015

Individual visits to the reservoir site and to view the reservoir cores may begin (optional for Participants who have executed Appendix 1 and submitted Appendix 2)

November 15, 2015 and ongoing

Participants' Offer Form Webinar for Participants approved for Data Room access

April 2016 (date and time TBD)

Deadline for PG&E to receive Offers

June 1, 2016 by 1:00 P.M. PPT

PG&E notifies all Participants of their Offer eligibility for Shortlist Negotiations

August 3, 2016

Participants accept Shortlist position, and post any Shortlist Offer Deposit, as applicable

August 17, 2016

PG&E negotiates with Shortlisted Participants

August 2016 - February 2017 (approximately)

2015 CAES RFO protocol and appendices

Participants' webinar

PG&E hosted the Participants' Webinar for the CAES RFO on October 29, 2015 from 1:30 P.M. to 3:30 P.M. (PPT). The presentation of this event, along with the audio file are available below.

If the audio portion of the Bidder's Webinar does not open in your browser, you will need to open the Windows Media Player and copy the URL into your media file application.

Offer form webinar

PG&E will hold an Offer Form Webinar for Participants that have been approved and granted access to the Data Room once the Offer Form has been finalized in March 2016.

Power Advocate instructions and registration information

Important Information

All Participants who are interested in submitting an offer package into PG&E’s 2015 CAES RFO will need to register with Power Advocate before submitting an offer into the RFO. To register at Power Advocate, click on the following link:

Only those Participants that have been accepted through the Power Advocate platform will be permitted to bid into this RFO.

We encourage you to register now.

Power Advocate Instructions

All offer package materials must be submitted on the Power Advocate site by the schedule and time indicated above.

Download: Power Advocate Instructions (PDF, 214 KB)

Data Room

PG&E will post all Project-related documents associated with this RFO in an electronic data room ("Data Room"). The Data Room contains PG&E's findings on geology, preliminary engineering, environmental analysis, and other information that PG&E has gathered through testing and analyses of the site. An overview of the contents of the Data Room is provided in Appendix 3, Data Room Contents.

Participants will need to refer to these documents to prepare their Offers.  The amount of information available in the Data Room is very sizeable and complex; therefore, Participants are encouraged to take the steps necessary to obtain access to the Data Room as soon as possible.

In order to access the Data Room, Participants will need to submit to PG&E's Power Advocate site the documents noted below, and available in the preceding section.  Participants who fail to execute the Confidentiality Agreement or lack sufficient experience and qualifications will not be provided access to the Data Room. PG&E requests that Participants submit required materials to gain access to the electronic Data Room no later than 1:00 P.M. PPT on April 13, 2016.

  • Appendix 1 - Confidentiality Agreement
  • Appendix 2 - Experience, Qualifications, and Organization

Other resources

Contact Information

For information or questions about PG&E's CAES RFO please email, and the Independent Evaluator, Frank Mossburg, at