If you thought going green was a fad, think again. Environmental consulting is a robust and growing industry, valued at $17.8 billion, according to data from IBISWorld. Growth of 9 percent a year over the next five years is expected.

This industry is well suited to independent contractors with the skills to install environmentally friendly gear such as wind turbines, solar panels, and green roofs. Every area, from government to the individual household level, is expected to thrive.

Looking to specialize? Expertise will be in demand in the fields of air-, soil-, and water-quality management, as well as sustainability studies as they pertain to development projects.

By the numbers:

Expected annual revenue growth through 2015, according to IBISWorld: 9 percent

Percentage growth in recent employment in environmental consulting, according to IBISWorld: 5.8

Average company profit margin in environmental consulting, according to IBISWorld: 5.6 percent

Estimated size of entire environmental consulting industry, in billions of dollars: $17.8