Power shifts

Just over a week ago, executives from several local alternative energy firms traveled to Washington to meet other industry leaders and discuss challenges to the sector, including competition for financing. Among the concerns: the future of ARPA-E, a federal agency that has doled out hundreds of millions of dollars to advanced energy projects across the country since 2009, and tens of millions in Massachusetts.

“One of the big challenges with the federal budget is whether ARPA-E is going to be funded,’’ said Peter Rothstein, president of New England Clean Energy Council, a trade group in Boston.

Ultimately, both government and venture capitalists may need to abandon scattershot approaches that seed an array of firms and begin to target investments - analyzing which companies, industries, and activities may have competitive advantages to succeed. As a result, all may not survive.

Here’s a look at key components of the Massachusetts alternative energy sector, and how they stack up:

Advance batteries and storage As the nation moves toward wind, solar, and other sources that produce electricity intermittently, the importance of advanced batteries and technologies to store this power is only expected to grow.

Massachusetts is already a leader in this area, with at least four of the industry’s best known firms, including A123 Systems. Headquartered in Waltham, A123 has more than 3,000 employees worldwide, including 300 in Massachusetts. Its high-powered, quick-charging batteries have been used in New York City buses, specially-adapted Priuses, and - most recently - regional energy grids.

Last year, the company opened two manufacturing plants in Michigan - which it built, in part, with nearly $250 million in federal stimulus funds. It hopes to become a major supplier for the automotive industry, which is launching electric vehicles. That expansion, in turn, has fueled growth in Massachusetts, where A123 does research and development, and designs large-scale energy storage systems.