Energy conservation can't do it all when it comes to meeting Texans' growing demand for electricity. Nor can wind power. And it could take more than a decade to get a new nuclear plant built.

Rising electricity demand could leave Texas facing a power shortage by 2010. No one wants a future of brownouts and blackouts.

Reality dictates that Texas is going to need new coal-fired power plants such as the 11 units that Dallas-based TXU is proposing to build. And the state will need them sooner rather than later to ensure a reliable electricity supply that isn't vulnerable to frequent interruptions.

That's the conclusion reached by the Star-Telegram Editorial Board after research and conversations with those both for and against the plants, including TXU executives, elected officials, and environmental and public-interest organizations.

The reason that Texas and the Dallas-Fort Worth area will need more power generation in both the near and long term can be summed up in two words: population growth.

Texas' population is projected to jump nearly 50 percent during the next 30 years, from 23.5 million to nearly 34.6 million, according to a mid-level growth scenario by the Texas State Data Center. The population of 10 D-FW area counties is expected to swell slightly more than 50 percent by 2030, rising from 6 million to 9.1 million.

This dramatic growth is expected to escalate demand for electricity. Even with significantly increased energy conservation, more juice will be needed to heat and cool homes and offices, power computers, do the laundry and keep the lights on.

The bottom line? Freezing in the dark is not an option. Nor is frying in the brutal heat of a Texas summer. An unreliable electric power supply also could cause good-paying businesses such as computer chip plants to shy away from locating here.

TXU is proposing to build 11 pulverized-coal plants that would be much cleaner and more efficient than those constructed in the past. The plants would have far lower emissions of three major federally regulated pollutants -- sulfur dioxide, nitrogen oxides and mercury -- than older facilities.

In addition, TXU has pledged to spend $500 million retrofitting four older coal plants. The net result, after the 11 new plants are completed and the older plants retrofitted, would be a 20 percent overall reduction in emissions of the regulated pollutants, company officials said.

There is concern that TXU's plan would result in greater amounts of polluting emissions blowing into the D-FW area on hot summer days and contributing to the region's continued failure to meet federal air quality standards for harmful ground-level ozone.

We can't say whether that would happen, but the Metroplex should put a greater emphasis on reducing emissions from a much larger contributor to ozone pollution: mobile on-road sources ranging from cars to 18-wheelers and mobile off-road sources such as construction equipment.

TXU is seeking permits from the Texas Commission on Environmental Quality to build the proposed plants. Critics complain that coal is a dirty fossil fuel and that TXU isn't planning to use new integrated gasification combined cycle (IGCC) technology that would greatly reduce emissions of carbon dioxide, the major greenhouse gas believed to contribute to global warming. TXU's 11 plants, as proposed, would discharge 78 million tons a year of carbon dioxide.

At present, CO{-2} emissions are unregulated, but Congress is considering putting mandatory controls on them.

TXU officials say that they don't want to use the IGCC technology because it is largely unproven and not well-suited to the Wyoming coal and Texas lignite that would burn in the company's new plants. In addition, the IGCC plants probably would cost substantially more and could take longer to build.

We previously have urged that Congress consider adopting legislation to begin regulating CO{-2} emissions. But technology to reduce carbon emissions isn't fully developed. TXU officials have said they would build their coal-fired plants so that they later could be retrofitted to accommodate new technologies to capture and store carbon.

We have expressed concern with Gov. Rick Perry's call for "fast-tracking" the permitting process for the TXU plants. This work should be neither rushed nor needlessly drawn out. The process should be conducted at a pace that will allow all interested parties to have their views fully heard.

Additional coal-fired plants are needed, but we can't say with certainty whether all of TXU's 11 proposed plants will be necessary. Changing, currently unforeseen circumstances might dictate a smaller number.

TXU plans to spend $10 billion constructing the 11 plants, which would benefit from a standardized design and economies of scale realized from building such a substantial number. But building a coal plant takes roughly four years, and costs could rise as a result of heavy nationwide demand for new coal plants, with approximately 150 already on the drawing boards.

As a result of Texas' adopting electric deregulation, TXU and its shareholders would assume the risk for unexpectedly high construction costs for the plants, company officials have said. That's a stark contrast to the regulated era, when TXU ratepayers took a hit for billions of dollars in construction cost overruns on the company's Comanche Peak nuclear power plant.

One of the advantages of building the cleaner coal-fired plants is that they would reduce Texas' exceptionally heavy reliance on natural gas-fired power plants. Electricity prices have risen sharply in recent years, primarily as a result of increased natural gas prices. Although gas prices have dropped considerably in the past year, they still are substantially higher than in earlier years.

To further diversify its power generation capabilities, Texas should consider building more nuclear power plants, which basically have no polluting emissions. But Texas must increase its generating capacity in much less time than it would take to build nuclear plants. They therefore are only a longer-term option.

We should make this clear: New coal-fired plants are by no means the only solution to meeting Texas' mounting electric power demand in the near term.

Alternative energy sources such as wind and solar power should continue to be developed and expanded. Texas is No. 1 in wind power generation capacity, but it still meets only a tiny fraction of the state's electricity needs. On summer afternoons when Texas' power demand peaks, wind turbines might generate little electricity because the air often is still.

Energy conservation also should play an increasingly large role in curbing power demand, and the Legislature should take steps to mandate that. For example, the state and electric utilities could develop stronger programs to give rebates to consumers for buying more energy-efficient heating and cooling systems and appliances.

Individuals also can help through voluntary actions such as raising their thermostats another degree or two in the summer or putting new insulation in their attics.

Such measures are important, but can't accomplish all that is needed. That's why cleaner coal-fired plants must be part of the solution.