Two studies released this week reinforce the belief that the expansion of clean energy and energy efficiency is an effective engine for job creation.

Looking back, the Pew Charitable Trusts released a reportdetailing job creation in clean energy between 1998 and 2007, finding that jobs in clean energy have grown at more than double the rate of overall jobs. Looking forward, University of California, Berkeley professor David Roland-Holst evaluated California's expected future demand for energy and outlined the potential for job creation in clean energy.

The Pew study's finding that clean energy jobs have grown by 9.1 percent while jobs elsewhere grew by 3.7 percent should be no surprise. During the 21st century, concerns about climate change, energy independence and peak oil have escaped the attic of anonymity to jointly galvanize popular opinion in support of clean energy development and a retreat from fossil fuel dependence.

Surprisingly, jobs related to clean energy and energy efficiency are quickly catching up to the centuries' old fossil fuel sector. Pew found that fossil fuel jobs numbered 1.27 million workers in 2007 while clean energy jobs totaled 770,000.

The U.C. Berkeleystudy found that if California can move to 50 percent renewable energy by 2050, the state would create half a million jobs.

Not surprisingly clean energy is also more job intensive than fossil fuels. "Clean energy is more job intensive than our current energy mix, creates and retains more wealth inside our state, and reduces our vulnerability to volatile fossil fuel markets," reported study author Roland-Holst. The growth in jobs would be significant even if a quarter of the equipment manufacturing is done outside the state.

Job intensity of energy production is an interesting area that warrants further study. The Berkeley study did compare the job intensity per megawatt hour of clean energy production, and found that solar requires the most relative jobs. In many cases solar power is also the most expensive to generate, so there's an obvious tradeoff.

Those clean energy jobs in many cases add the indirect costs of health, vacation, and retirement benefits for workers, which is great for the workforce but a financial burden on the company. Therefore, in a perfect world the cost per kWh would be balanced against the number of jobs created. From an economy-wide standpoint, it's better to have people working than not, but hiring companies can overburden themselves with a workforce that carries a high long term cost (the folks in the auto industry know all about that.)

Keeping things local -- the jobs and money - is what makes clean energy vital to the economy. Paying solar installers, contractors and farmers who harvest biofuel feedstock the same dollars that otherwise would go to foreign oil companies will ripple across the entire economy as the money is re-spent again and again.

According to the study, money saved by consumers on energy efficiency is the most potent local economy stimulus. A dollar taken off the energy bill will be spent on other things that will equal from 10 to 100 dollars in wages for new workers.

The American Recovery and Reinvestment Act is seeking to strike that balance by providing incentives that can make renewable power competitive with fossil fuels, which still receive considerable tax breaks in their own right.

John Gartner is Editor in Chief of Matter Network and an Industry Analyst for Pike Research