Beckerman PR continued its rapid growth this week with the acquisition of the Atenna Group, a 15-person San Francisco firm focused on clean technology clients.

The Atenna Group will retain its brand and staff under the leadership of founder Melody Haller. The combined firm has approximately 75 employees and a considerable stable of alternative energy clients including 3M’s Renewable Energy Group, Atlantic Green Power, BioSolar, BlueFire Ethanol, Akeena Solar, eSolar, EV Connect and a number of others. The release states that it’s the largest clean tech practice in U.S. PR.

Michael Beckerman began expanding beyond a base of regional real estate and professional services clients a year ago with the acquisition of Keith Zakheim‘s Avalanche agency, consolidating most of the staff to a space in Hackensack, NJ.

A few months later, Beckerman picked up Manhattan boutique Wise PR.