Pierce Atwood’s roots in Maine stretch back more than 120 years. But as it moves through the 21st century, the Portland, Maine-based firm is looking beyond the Pine Tree State and expanding its reach in New England and Washington.

And it doesn’t plan to stop there.

Firm leaders see potential to leverage the expertise of its energy practice into national and global growth. Pierce Atwood’s energy expertise dates to around 1919, when Central Maine Power Co., the state’s primary utility, became a client.

Today, attorneys in the 140-lawyer firm have represented the state of California in energy matters and worked with the Saudis on an energy project.

One of the ways the energy group has tapped into energy business is through the creation of the Financial Marketers Coalition, designed to give electric energy ­clients a say on regulatory controversies and a voice in the regulatory process.

Clients can access information via extranet and participate in conference calls with partner Carol Smoots on pressing issues and strategic matters, saving money by sharing resources.

Wes Allen, chief executive officer of Red Wolf Energy Trading LLC in Raleigh, N.C., said the coalition gives small energy-trading businesses like his a fighting chance against powerful utilities that can afford to hire lobbyists. "Carol has kept our company and companies like us in business for years," Allen said. "If we hadn’t been working with Carol in the past 10 years, we wouldn’t be around. The utilities would have squeezed us out."

But the firm sees a broader future for itself. Managing partner Gloria Pinza has been hunting for office space in Boston for the burgeoning practices in intellectual property and technology; litigation; and midmarket mergers and acquisitions work. The office opened about six years ago, and the space it leased two years ago is already insufficient to accommodate its 40 employees, 26 of them lawyers.

One way Pierce Atwood holds down its costs is through a closed compensation system, which Pinza said encourages teamwork and collaboration.

"If I know it’s just as valuable to the firm to be putting a team together to serve the client as it is for me to claim I individually got that client, the client is best served," she said. "The client wants the right answer from the right person. They don’t want 18 layers of people. We think our system enhances that."