The utility TXU Corp. said Monday it will offer high-speed Internet service over power lines to several million Texans as part of a $150 million project aimed at improving its ability to monitor the power grid.

The "smart grid" buildout will enable what would be the nation's largest broadband-over-power line Internet rollout.

The 10-year partnership with Current Communications Group Inc., a privately held company in Germantown, Md., is not, however, expected to yield residental Internet service until the second half of 2006.

Once completed, the grid will let TXU check meter consumption remotely and pinpoint problems before they become major blackouts.

TXU spokesman Chris Schein said Internet access was secondary to the smart grid capabilities.

"We really believe that what end users are going to appreciate is when the spring storms hit and they don't have an outage," he said. "Or if they do have an outage, it's not as long as it was."

Construction on the smart grid system will begin early next year along TXU's 14,000 miles of transmission lines and 100,000 miles of distribution lines.

The deal gives Current access to more than 2 million business and residential customers, mostly in the Dallas-Fort Worth area.

Proponents say broadband-over-power line technology, or BPL, could be especially significant for rural areas, where high-speed Internet access has lagged due to the higher costs to telecommunications and cable companies of serving sparsely populated areas.

Though pricing and download speeds haven't been finalized, Current vice president Jay Birnbaum expects to compete directly with cable and DSL providers. BPL moves data at roughly the same speeds as cable or DSL lines.

Current's only existing widespread availability is through Cinergy Corp. in Cincinnati, where it charges between $20 to $45 monthly for Internet speeds of up to 3 megabits per second. Birnbaum wouldn't provide subscriber numbers but said the service was available to about 50,000 customers in Ohio.

Current, which counts Google Inc. and The Hearst Corp. among major investors, has smaller pilot projects in Hawaii, Maryland and Southern California.

Most BPL offerings remain in the test phase, said Alan R. Shark, executive director of the Washington-based Broadband Over Power Lines Industry Association.

One of the current largest rollouts is in Manassas, Va., where 850 subscribers have signed up since the municipal utility began offering BPL in October.

Shares of Dallas-based TXU Corp. were down $1.49 to close at $52.09 in trading on the New York Stock Exchange. Shares have ranged from $30.22 to $58.29 in the past year.