Millis adds battery‑storage and data‑center definitions to zoning, amends to bar data centers town‑wide

The Zoning Bylaw Review Committee and planning board proposed adding definitions for Battery Energy Storage Systems (BESS) and data storage centers and adding BESS tiers to the Table of Use Regulations. Nicole Riley, planning board member and Zoning Bylaw Review Committee chair, said the three tiers mirror recent state definitions in the 2024 Climate Act — tier 1 under 250 kilowatt‑hours, tier 2 between 250 kWh and 10 megawatt‑hours, and tier 3 between 10 and 100 megawatt‑hours — and noted the state’s streamlined permitting for systems up to 100 MWh would take effect July 1.

Riley and planning officials told Town Meeting they could not obtain a moratorium from the Attorney General on these uses and that, without local zoning, applicants could use the state’s streamlined process and site BESS or related facilities without local restrictions. To provide local control, the article adds definitions and places most larger BESS and data storage centers in industrial districts. During debate a motion to amend the proposed Table of Use Regulations changed the entry for "data storage center" so that such uses would not be allowed in any district; that amendment was adopted. Proponents said the change gives the town time to study data‑center issues (energy and water use) and to consider more detailed bylaws.

Residents asked practical questions — for example, what tier‑1 units look like — and Riley described tier‑1 systems as residential wall‑mounted battery packs similar to commercial powerwall products (several feet tall and under one foot deep) and said larger systems would be handled under special permitting in industrial areas. Planning and energy committee members said the article puts basic zoning definitions on the books while preserving the ability to revisit and refine policy through further study and public outreach. Town Meeting approved the article as amended; proponents said the change prevents data storage centers from being sited anywhere in Millis while allowing smaller battery storage systems under defined tiers.