Nov. 21--Michigan's 21st Century Energy Plan is to be released by the end of the year, and utilities and environmentalists are weighing in on what the program should contain.

State regulators are considering whether a certain percentage of Michigan's electricity must come from renewable fuel sources such as solar, wind and hydroelectric.

Twenty-three states and the District of Columbia have targets, with dates, for renewable energy sources, ranging from 1% to 25% of total power. For example, Illinois recently adopted a voluntary standard of 25% of energy from renewables by 2017.

Michigan utilities currently generate less than 8% of their electricity from renewable sources.

In April, Gov. Jennifer Granholm issued an executive directive challenging Michigan Public Service Commission Chairman Peter Lark to come up with a comprehensive plan to meet Michigan's electric needs in the future.

The final report is due Dec. 31, but it is still unclear what implementation targets it will set.

Environmentalists are pushing for Michigan to keep up with neighboring states.

"We need to look at matching what other states in the Midwest are doing, at least," said Mike Shriberg, executive director of Environment Michigan.

"Anything under 10% by 2015 is the absolute floor for any responsible renewable portfolio standard. If Michigan wants to be a leader on this, you have to grow your renewables by 1% a year," Shriberg said.

Public service commissioner Monica Martinez responded: "I think we do have to venture into this. I'm for promoting renewables in Michigan. But we've got to figure out the economics."

One point of debate is whether a Michigan standard should be mandatory or a goal.

Consumers Energy has said a mandatory program might be too ambitious and could end up costing customers more money.

"From our perspective, we're doing our part, and more renewable energy is being produced in Michigan because of the Green Generation Program, but 20% doesn't seem reasonable," said Dan Bishop, a Consumers spokesman. "We just think whatever approach is adopted ought to be fair."

Consumers Energy, a unit of Jackson-based CMS Energy, began its Green Generation renewable energy program voluntarily in September 2005. The utility, which has about 1.8 million electric customers, will get between 6% and 7% of all its energy generation from renewable sources, such as windmills and landfill gases.

DTE Energy, the state's biggest utility with 2.2 million electric customers, has expressed reservations in the past, but recently has sounded much more supportive of a renewables standard.

The standard "should be a part of the state energy strategy that addresses the state's long-term needs for generating capacity at stable competitive prices," said Len Singer, a spokesman for DTE. "We would hope that any standard ultimately adopted in Michigan applies to all market participants, is well defined and economically viable."