SAN FRANCISCO — In the wasteland that is the real estate sector, some land use lawyers are finding a tiny but growing oasis of activity in renewable energy.

For Cox, Castle & Nicholson partner R. Clark Morrison, for example, work for homebuilders used to account for about 65 percent of the traditional-development portion of his billings in 2005. Now, it’s about 10 percent. “It’s gone down pretty significantly,” he said. “I’ve never seen anything like this.”