Nearly two-thirds of tax professionals are unaware of the various tax incentives that are available to private investors in clean energy projects, according to a new poll by Bloomberg BNA.

The online survey, conducted in consultation with Bloomberg New Energy Finance, polled subscribers to Bloomberg BNA's Tax and Accounting Center, found that 35 percent of the respondents have made tax equity investment either directly or on behalf of clients in areas other than clean energy, such as low-income housing. Nevertheless, 65 percent said they were mostly or completely unfamiliar with the incentives available to backers of US wind projects known as the Production Tax Credit.

Only 7 percent of the survey respondents described themselves as extremely familiar with the PTC, which was used to finance approximately 4,000 megawatts of wind capacity in 2011, or around 70 percent of total U.S. wind installations, according to Bloomberg New Energy Finance estimates.

The survey comes as the U.S. clean energy sector seeks to grow by attracting new private investment from corporations in the form of tax equity. Bloomberg New Energy Finance presented the results of the survey Tuesday at a White House meeting hosted by the U.S. Department of Energy.  The event included CFOs and others from Fortune 500 companies as the administration highlights opportunities available to large corporations in clean energy tax equity investing.

When asked why they or their clients had not made a clean energy tax equity investment, a majority of the survey respondents answered that it was either not a strategic fit with the company's business or they believed there were better returns available elsewhere.  Twenty-one percent of those answering the question responded that they did not make the investment because they were unaware of a tax equity option. Nearly all of the survey respondents indicated that a clean energy investment would be for the purpose of supplying the client's own energy needs.

Separately, an attempt in the Senate on Tuesday to extend expiring tax breaks for wind energy, biofuels and energy-efficient homes failed to pass on Tuesday. The lawmaker who sponsored the measure, Sen. Michael Bennet, D-Colo., plans to try again later this year before the tax breaks expire, according to the Huffington Post.