Eos Energy Storage — Hazardous Materials Safety Interpretation

Page 11200 New Jersey Avenue, SE Washington, DC 20590 U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration February 24, 2022 Heidi Countermine Project Logistics Manager Eos Energy Storage 3920 Park Ave. Edison, NJ 08820 Reference No. 21-0103 Dear Ms. Countermine: This letter is in response to your November 11, 2021, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to electric storage batteries. Specifically, you seek confirmation that the shipment of your company’s electric storage batteries is eligible for the exception from the requirements of the HMR as currently specified in § 173.159(e). In your letter, you state that your company manufactures an electric storage battery and loads the product into a fully enclosed energy storage system—i.e., a custom-built ISO container—under certain conditions including the following: • The batteries are classified and described as “UN2794, Batteries, wet, filled with acid, electric storage, 8”. • Each individual battery is enclosed in plastic housing with no exposed terminals. • The batteries are loaded and braced into individual slots in the steel racks of the custom- built container, and provide a photograph illustrating this manner of loading and bracing. • No other hazardous materials are shipped in or with this fully enclosed container. • The motor vehicle or rail car will not contain any other commodities.#

Page 2Based on the information and photographs provided, it is the opinion of this Office that the details provided of shipments of these batteries meet the requirements provided in § 173.159(e) for exception from the requirements of the HMR. I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, Dirk Der Kinderen Chief, Standards Development Branch Standards and Rulemaking Division#

Page 3Casey 21-0103 From: INFOCNTR (PHMSA) To: Hazmat Interps Subject: FW: Interpretation Request - Eos Energy Storage Batteries, UN 2794 Date: Friday, November 12, 2021 2:19:57 PM Attachments: image004.png image006.png Hello, Below is a request for letter of interpretation. Thanks, Jonathon, HMIC From: Heidi Countermine <hcountermine@eose.com> Sent: Friday, November 12, 2021 2:14 PM To: INFOCNTR (PHMSA) <INFOCNTR.INFOCNTR@dot.gov> Subject: RE: Interpretation Request - Eos Energy Storage Batteries, UN 2794 CAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or open attachments unless you recognize the sender and know the content is safe. Per request, our mailing address for letter of interpretation is: Eos Energy Storage 3920 Park Ave. Edison, NJ 08820 Heidi Countermine | Project Logistics Manager | C: 518 488 4114 eose.com + LinkedIn + Twitter From: Heidi Countermine Sent: Thursday, November 11, 2021 9:32 AM To: 'infocntr@dot.gov' <infocntr@dot.gov> Subject: Interpretation Request - Eos Energy Storage Batteries, UN 2794 Hello, I am writing to request a formal interpretation on the requirements for shipping a Battery Energy System over the road under the 173.159(e) exemption in the 49 CFR. If exemption applies, I understand I would not need placards on the truck or hazmat data on the bill of lading. I believe we have met all requirements for shipping under this exemption, but would like clarification if I am understanding the exemption correctly for our product.#

Page 4My company, Eos Energy Systems, manufactures an electric storage battery and loads this product into a fully enclosed energy storage system unit with the following conditions: Batteries are classified as UN 2794, Batteries, wet, filled with acid, Class 8 The battery contains a proprietary non-flammable aqueous electrolyte solution containing zinc bromide The batteries are shipped fully discharged, at a voltage less than 5 volts Each individual battery is enclosed in plastic housing with no exposed terminals, as demonstrated in Image #1 below The energy storage system is a custom built 20’ ISO container with steel racks affixed inside. The batteries are loaded and braced into individual slots in the steel racks as demonstrated in Image #2 below No other hazardous materials are shipped in or with this fully enclosed unit The transport vehicle will not contain any other commodities IMAGE # 1 IMAGE # 2#

Page 5Best Regards, Heidi Countermine Project Logistics Manager 518 488 4114 Mobile eose.com + LinkedIn + Twitter Eos Electronic Communication Disclaimer: This message and any attachments are solely for the use of intended recipients. The information contained herein may include trade secrets, protected health or personal information, privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you are not an intended recipient, you are hereby notified that you received this email in error, and that any review, dissemination, distribution or copying of this email and any attachment is strictly prohibited. If you have received this email in error, please contact the sender and delete the message and any attachment from your system.#

Page 6Thank you for your cooperation.#