A new report analyzing the potential of Florida's forests to provide renewable energy sources could raise further doubts about proposed state goals to increase renewable energy.

The Legislature in 2008 adopted a comprehensive energy bill that directed state agencies to study the economic effects of providing financial incentives for biomass energy production from trees or waste wood.

The report, which was sent Thursday to the governor and Legislature, says that Florida's forests could support a 7 percent renewable energy goal for the state.

But a 20-percent goal by 2020, which has been recommended by Gov. Charlie Crist and the Florida Public Service Commission, could create "dramatic" price increases for wood products and cause forests to be harvested at unsustainable levels, the report said.

In letters to Crist and House and Senate leaders, Agriculture Commissioner Charles H. Bronson said the report shows that a "significant amount of renewable energy" can be produced from woody biomass. But he also said more forest replanting is needed along with the increased use of wood waste and other measures.

Florida now produces only 1.9 percent of its energy from renewable resources, and woody biomass contributes about one-third of the total existing renewable energy produced in the state, according to the study.

The study concluded that only a 7-percent renewable energy goal, with 1 percent to 3 percent from woody biomass, would have little impact on the existing forest products industry. Increased timber harvesting would bring about a relatively small increase in the economy, jobs and state revenue, the report said.

Timber harvesting with more aggressive reforestation would be needed to maintain sustainable forests. Higher renewable energy goals would at least require the planting of faster-growing "energy crops" that could include non-native tree species, such as eucalyptus.

The 20-percent goal, with 15 percent from woody biomass, would cause a significant redirection of wood from pulp and paper, lumber and other forest products industries to electricity generation, causing a "quite dramatic" increase of up to 500 percent for some forest products.

Sen. Nancy Detert, R-Venice, has filed legislation for the 2010 session that would establish a 15-percent renewable energy goal. A similar bill last year passed the Senate but was not heard in the House.

Jeff Doran, executive vice president of the Florida Forestry Association, said the study shows the importance of supporting strong markets for trees by building facilities appropriately so that forests are not over-harvested or underused.

John Bonitz, farm outreach coordinator of the Southern Alliance for Clean Energy, said he realizes the proposed 20-percent goal could be a "stretch" but he still thinks it can be reached with improved forest management.

"We think they (energy goals) are a great deal for the local economy in every state where they are being proposed," he said.