Some of the most challenging and well-paid jobs are emerging from the "green" economy, as alternatives to fossil fuels, environmentally sound building concepts, and solar and wind power projects gain traction as desirable -- and profitable -- endeavors.

Green jobs are attractive for several reasons, not the least of which is that there is incredible growth potential. In addition, most of these jobs pay very high salaries, and there are positions available for those with two-year, four-year, and graduate degrees.

Here are three states that are leading the way in the creation of a variety of green jobs as they embrace energy efficiency, alternative fuel production, and other sustainable projects.

Massachusetts
Early this year, Massachusetts embarked on an energy-efficiency extravaganza. The state plans to retrofit 700 state buildings during the next three years with an eye toward energy savings, spending about $400 million, and creating up to 4,000 new jobs.

Massachusetts is not new to sustainable building practices. Last year, the state announced over 100 Leadership in Energy and Environmental Design certified building projects, which earned it a No. 4 ranking in the U.S. Green Building Council's top 10 LEED states last year.

Jobs in the sustainable building industry are many and diverse, much like traditional building trades. Most often, those who work in the green construction industry have certifications such as LEED. Examples of available jobs, with 2010 median annual salaries, courtesy of the Bureau of Labor Statistics, would be: urban and regional planners, $63,000; architects, $77,000; electrical engineers, $84,000; and construction managers, $85,000 -- just to name a few.

Hawaii
An abundance of sun likely explains Hawaii's love affair with solar, and the state is No. 11 out of the 50 U.S. states as far as solar capacity is concerned. Also, like Massachusetts, Hawaii has embarked upon a building rehabilitation project, spending $300 million to renovate government buildings to make them more efficient, thereby moving the state closer toward its goal of reducing energy consumption by 30% by 2030.

In addition to green construction jobs, the state will be creating jobs necessary to carry out its solar initiative, such as engineers and installers, as well as building operators.

Some examples of these types of jobs, according to BLS, would be materials engineers, with a median salary of $86,000, and industrial engineers, who make around $84,000 per year. Power plant operators earn more than $64,000 yearly, and plumbers and steamfitters, who can be involved in many facets of the solar economy, earn over $66,000 annually.

California
Not surprisingly, California has one of the most active green economies, encompassing solar, wind, transportation, and biofuel production. In the second quarter of this year, the Golden State was slated to create more than 9,000 of the nationwide 38,000 green jobs announced during that span of time, according to Environmental Entrepreneurs.

California offers a plethora of jobs in the sustainability industry, one portion of which is biofuels. The state has close to 30 biofuel companies, and jobs are plentiful in this part of the green economy. As usual, engineering jobs are abundant, with chemical engineers, at a median 2011 annual pay rate of over $96,000, being one of the top positions in the biofuel industry. Chemistry is huge here, with chemists making well over $75,000 per year, and chemical technicians, with an annual salary of nearly $50,000, also in demand.

This is just a smattering of jobs available in the green economy. While many jobs -- like architect, chemist, and most engineers -- require a bachelor's degree, chemical technicians need only an associate's degree. Others, like plumbers and power plant operators, require an apprenticeship and/or on-the-job training.

It is worth noting that credentials such as LEED are becoming more popular -- and desirable. A recent poll by the Poplar Network, an education network of professionals in the green building industry, noted that 84% of members polled agreed that knowledge of green concepts has helped drive their careers. As more states take on environmentally sound projects, the green economy will continue to be a source of high-paying, satisfying jobs.