The justification for clean energy in recent years has been the promise of green jobs, especially since the recession hit three years ago. Getting a handle on how many, beyond simple counts like solar installers and wind turbine assemblers, is a bit trickier.

The Brookings Institution tried to bring some order out of this apparent chaos with a recent report, “Sizing the Clean Economy.” 

“Not only do “green” or “clean” activities and jobs related to environmental aims pervade all sectors of the U.S. economy; they also remain tricky to define and isolate—and count,” the report says.

The lack of standard definitions and available data is only a start. So the Metropolitan Policy Program at Brookings worked with Battelle’s Technology Partnership Practice to develop a detailed database of establishment-level employment statistics pertaining to a sensibly defined assemblage of clean economy industries in the United States and its metropolitan areas.

As has been reported here previously, many clean energy jobs have been created when industrial companies in the Midwest were forced to find new markets when their footholds in the auto markets eroded.  Think boltmakers for wind turbines, glass makers for solar farms. Most clean economy jobs reside in mature segments.

A smaller portion of the clean economy encompasses newer segments  like solar photovoltaic (PV), wind, fuel cell, smart grid, biofuel, and battery industries.

Other highlights include:

The clean economy is manufacturing and export intensive. Roughly 26 percent of all clean economy jobs lie in manufacturing establishments, compared to just 9 percent in the broader economy.

The clean economy offers more opportunities and better pay for low- and middle-skilled workers than the national economy as a whole. Median wages in the clean economy—meaning those in the middle of the distribution—are 13 percent higher than median U.S. wages. Yet a disproportionate percentage of jobs in the clean economy are staffed by workers with relatively little formal education in moderately well-paying “green collar” occupations.

Most of the country’s clean economy jobs and recent growth concentrate within the largest metropolitan areas. Some 64 percent of all current clean economy jobs and 75 percent of its newer jobs created from 2003 to 2010 congregate in the nation’s 100 largest metro areas.

Strong industry clusters boost metros’ growth performance in the clean economy. Clustering entails proximity to businesses in similar or related industries. Establishments located in counties containing a significant number of jobs from other establishments in the same segment grew much faster than more isolated establishments from 2003 to 2010. Examples include professional environmental services in Houston, solar photovoltaic in Los Angeles, fuel cells in Boston, and wind in Chicago.

One caveat is that policy uncertainty is taking its toll. Market demand for clean economy goods and services is uncertain, impacting the financial markets. In the meantime, global investment has been moving to foreign shores, which is an old story in itself.