ALBANY — When Governor Spitzer today unveils the details of his clean-energy initiative, he will announce multimillion-dollar state investments in wind and solar power, plans for a new fleet of power plants that emit less carbon dioxide, and a variety of conservation goals.

Absent from the first major energy speech of his administration will be any discussion of ethanol, a notable policy departure from his predecessor, Governor Pataki, who touted the alternative fuel as the wave of a greener future and aggressively tried to encourage its production and use.

“He’s not talking about ethanol at all tomorrow,” Mr. Spitzer’s top environmental adviser, Judith Enck, said in an interview yesterday. “So that should speak volumes.”

New York’s shift in energy policy is the latest in a series of setbacks for ethanol, which some have hailed as a cleaner alternative to gasoline that could help free America from its dependence on foreign oil.

The Spitzer administration is turning away from corn ethanol at a time when evidence is building that calls into question the wisdom of state policies and subsidies in support of ethanol.

“The governor is not closing the door on corn ethanol,” Ms. Enck said. “We’re just not enthusiastically boosting it as the previous administration has. We have concerns that corn ethanol is not as energy efficient as other sources, and there are also air quality concerns.”

New studies and reports have come out in the past month challenging the public perception of ethanol. One study found that ethanol-burning cars produce smog-causing pollutants that pose a greater danger to people and the environment than traditional gas-guzzling cars. Another report argues that rising ethanol production could spell greater world hunger.

The studies come on top of older reports showing that the production of corn ethanol requires more fossil energy than the ethanol fuel produced.

Instead of ethanol, the centerpiece of Mr. Spitzer’s energy agenda will be using state investments to build renewable energy projects, such as solar and wind generation, with a long-term goal of bringing the state closer to getting 25% of its electricity from renewable sources.

Mr. Spitzer is also looking to reauthorize Article X of the public service law to expedite the plant-siting process of electricity plants. An expansion of mass transit and investments in hybrid cars are also key pieces of his energy agenda.

During Mr. Pataki’s last year in office, he came out with an energy independence plan in which ethanol had a starring role.

His last budget provided tax credits to ethanol refineries, changed state regulations to make it easier for gas station owners to sell ethanol, put in place a plan to install ethanol pumps at all 27 New York State Thruway service plazas, and eliminated state taxes on ethanol and other fuels. Not all of the ethanol incentives benefited corn growers.

By the end of his term, Mr. Pataki was expressing most enthusiasm for cellulosic ethanol, which is made from wood chips and paper wastes and is seen as a more efficient form of the fuel.

While some praised Mr. Pataki for trying to reduce the state’s consumption of foreign oil, the former governor’s focus on ethanol struck some in Albany as a product of his presidential ambitions, allowing him to curry favor with Iowan corn farmers and the national agricultural industry.

Mr. Pataki, who hinted last year that he was gearing up for a presidential run, appears to have postponed indefinitely plans to enter the 2008 race.

Since he announced his energy plan last year, a backlash against ethanol has steadily picked up the pace.

An essay published in the most recent issue of the influential journal, Foreign Affairs, argues that the global surge in ethanol production is exhausting corn inventories and increasing corn prices, trends that could hurt poor developing countries by making food staples more expensive.

“If oil prices remain high — which is likely — the people most vulnerable to the price hikes brought on by the biofuel boom will be those in countries that both suffer food deficits and import petroleum. The risk extends to a large part of the developing world,” the authors, C. Ford Runge and Benjamin Senauer, wrote in an essay titled, “How Biofuels Could Starve the Poor.”

Skepticism about the fuel increased even further this week with the release of a Stanford University study taking aim at one of the core arguments made in favor of ethanol — that it’s a cleaner, safer energy source.

The author of the study, Mark Jacobson, used a computer air pollution model to determine that the trend toward E85 blended ethanol fuel in vehicles could have deadly consequences. Widespread use of E85-burning cars would lead to 4% more ozone-related deaths in nation, with the most harmful effects centering in greater Los Angeles, according to his study.

The danger posed by pollutants produced by the fuel — such as acetaldehyde and formaldehyde — outweigh the benefits of the decrease in other pollutants, the study said.