In the old Aesop fable, wind and sun battle over which is the stronger. The wind blows hard, but the sun shines hot. They both do their best to get a traveler to remove his jacket.

In the fable, sun wins. But in real-life policy questions over solar power and wind energy -- over which provides the more cost-effective source of clean energy -- it appears that wind has sun on the ropes. At least for the moment.

Both provide an environmentally friendly alternative to coal- and gas-fired electricity, and both emit none of the greenhouse gases associated with global warming. But solar power -- despite several advantages over wind -- is much more expensive, say experts.

"You get more bang for your buck from wind energy than from solar energy," said Ryan Wiser, who leads renewable-energy research at the Lawrence Berkeley National Laboratory in California.As the public expresses growing concern over both global warming and rising utility bills, consumer advocates say it's more important than ever to balance the costs and benefits of wind power, solar power and other forms of renewable energy.

It's not a question of whether the state should pursue clean-air strategies -- but rather which ones, and at what cost. Who stands to save money and who stands to pay more? Is nuclear power part of the solution?

No major state agency -- not the Texas Public Utility Commission, not the Texas Commission on Environmental Quality -- has been tasked with coming up with a comprehensive renewable-energy policy that balances the state's clean-air needs with consumer interests within the context of the state's deregulated electricity market. However, House Speaker Tom Craddick has created a special committee to study the state's long-term energy needs, as well as the effect of new power generation on global warming.

The Texas Public Utility Commission will take on some of the issues piecemeal in the coming months.

Sun vs. wind: Round 1

The solar-power industry already lags far behind wind in Texas, which recently leapfrogged over California to become the largest wind-power-generating state in the nation. And many more wind turbines are expected soon thanks to an aggressive and expensive plan at the PUC to build more transmission lines.

But California leads the nation in solar power and is pursuing even more through its Million Solar Roof Plan, which was signed into law by Republican Gov. Arnold Schwarzenegger in 2006.

A look at those two programs in both states provides useful points for comparison.

In California, the plan is to provide new publicly funded rebates for those who install solar panels at their homes and businesses. California is charging ratepayers about $3.3 billion -- or about $86 per Californian -- to finance the program. That amounts to about $1 per month on a typical bill over a period of years, according to a representative of the California Public Utilities Commission.

Policymakers say the rebates will increase California solar power output by 3,000 megawatts by 2018 -- or enough new power for about 1.5 million homes, under normal conditions.

By comparison, the Competitive Renewable Energy Zone program in Texas will lead to the construction of $3 billion to $6.4 billion in transmission lines -- all for wind power, and all constructed at ratepayer expense. That equates to anywhere from $150 to $320 for every Texan served by the state's power grid, although the exact impact on home bills won't be known until action later this year by the Texas Public Utility Commission. The cost will likely be spread over a number of years.

Under the Texas plan, the state hopes to encourage electric companies to build an additional 5,150 megawatts to 17,950 megawatts of wind turbines -- or enough for 2.6 million to 9 million homes.

Bottom line: Under the California plan, the development of an additional megawatt of solar power would cost ratepayers $1.1 million. Under the Texas plan, an additional megawatt would cost $356,000 to $573,000.

Sun vs. wind: Round 2

Experts also say solar power enjoys several advantages over wind -- advantages that increases the value of sun power for those paying the bills.

For instance, because the wind typically stops blowing during the middle of hot summer days, Texas won't get much use from those expensive new transmission lines when it needs the power the most. Obviously, that's not a problem with solar.

Wind also presents tough -- and sometimes expensive -- technical challenges. Because wind turbines will stop spinning without a moment's notice, engineers at the power grid must sometimes have more expensive standby power ready and waiting.

And finally there's the question of power lines themselves. With wind power, ratepayers get stuck with the enormous price tag. This cost is avoided with rooftop solar power and can be minimized with other sorts of solar energy.

Wind-power advocates argue that concerns over the transmission costs are overblown. They say that savings from wind power -- which has zero fuel costs -- quickly offset the extra expense.

But some skeptics say that under the deregulated electricity system in Texas, there's not a guarantee that ratepayers will see much of those savings. Instead, much of it may end up padding the bottom line of electric companies.

In California, by contrast, those who invest in solar panels can see savings reflected directly on their bills. Those savings -- when combined with federal tax breaks and the new California rebates -- can allow homeowners to recoup the cost of their investment in panels in a decade or so, said Marcel Hawiger, staff attorney for the Utility Reform Network, a California-based consumer advocacy group.

After that, the solar investment can lead to real reductions in home bills, he said.

Sun vs. wind: Round 3

Despite the advantages, Hawiger still questions whether that state's solar initiative is a good deal for Californians. He calls the $3.3 billion addition to home rates one of "the most regressive forms of taxation" and notes that most of those installing the panels are businesses, not residences.

"Our residential customers are subsidizing commercial customers who are already getting a much better tax break for solar installation," he said.

Like the effects of gravity, you just can't escape math. Even given the potentially high transmission costs and other disadvantages, wind power still remains much cheaper to produce than solar, said Severin Borenstein, director of the University of California Energy Institute.

He estimated solar power's long-run average production cost at 25 to 30 cents per kilowatt hour -- not including government subsidies and tax credits -- as compared to 5 to 9 cents for wind power. "Solar is four times as expensive than wind -- or at least three times as expensive -- even when you count transmission," he said.

Looking ahead

Hawiger, of The Utility Reform Network, said the most cost-effective way of reducing greenhouse gases remains energy-conservation efforts, and the adoption and enforcement of strict building codes that ensure that new homes are energy-efficient.

Cyrus Reed, advocacy director of the Lone Star chapter of the Sierra Club, calls for an aggressive ramp up of both solar and wind power, saying, "We need to incorporate solar power because it's an energy source whose cost is coming down."

Public Utility Commission Chairman Barry Smitherman said that the state must continue to rely on fossil fuels like coal but that fossil fuels "should be supplemented by wind, water, solar, biomass and nuclear energy." In a presentation in February, Smitherman said the state will need to increase its electric generation by 50 percent by 2030 because of population growth.

Geoffrey Gay, an attorney representing Fort Worth and other North Texas municipalities before the PUC, questioned whether new nuclear power makes sense. Although nukes create no air pollution, they nonetheless cost billions to build and require government subsidies.

Those questions and more may be taken up in the coming months by the Select Com- mittee on Electric Generation Capacity and Environmen- tal Effects, which was created late last year by Craddick and charged with studying the state's long-term electrici- ty needs, as well as the ex- tra capacity's effects on glo- bal warming and climate change.

The committee conducted hearings last week and plans more for the future.

Wind power - Pros:

• Zero pollution
• Requires fewer steps and less technology to convert to electrical power.

Wind power - Cons:

• Can be a hazard to migratory birds.
• Is expensive to install.
• Available only in areas of predictable and consistent wind.

Sun power - Pros:

• Solar power is constant and consistant in daytime in certain places.
• Zero pollution

Sun power - Cons:

• Commercial solar-power farms, which use ray-collecting panels, take more land out of productive use than wind farms.
• Requires more expensive equipment than wind power.
• Is available only in areas of sufficient and consistent sunshine.