Texas easily led the nation in wind power expansion last year.

The state added 3,615 megawatts of wind power in 2015, out of 8,598 new megawatts nationally, according to an annual report by the American Wind Energy Association.

And the Texas trend shows no sign of ending. A majority of the wind power capacity now under construction is in the Lone Star State, the report said. More than 5,000 megawatts are being built or are nearing construction in Texas, compared with less than 4,400 in the rest of the country.

“Texas continues to lead, continues to have a stronghold in the industry,” said Hannah Hunt, AWEA senior research analyst and report co-author.

But, she added, “it is fair to wonder how long this can continue.”

At the end of the past year, Texas accounted for nearly a quarter of the country’s wind power, with 17,713 megawatts in operation, compared with 74,472 megawatts nationwide.

One megawatt is typically enough to power about 500 Texas residences during mild weather or 200 homes during peak demand.

The Electric Reliability Council of Texas, which regulates about 90 percent of the state’s power grid, oversees about 16,000 megawatts of Texas’ wind power. It expects the grid to have about 21,000 megawatts of wind capacity by the end of this year, based solely on projects that have financing lined up.

After $7 billion in new power lines in much of the Texas Panhandle came online in 2014 to tie wind farms to the state’s more populous regions, Texas’ wind industry has surged. A recent extension of a federal production tax credit for wind projects is expected to add more.

Wind power is so bountiful in Texas that ERCOT has seen negative power prices recently during periods of strong wind overnight, when there is little demand for power. ERCOT recently counted a record 13,883-megawatt peak for wind power load Dec. 20. Wind power made up nearly 45 percent of the grid’s entire power load at one point that day.

While growth is continuing, power prices eventually may shrink to a point that new wind projects no longer make sense, said Dan Woodfin, ERCOT director of system operations. “At some point, it becomes uneconomical for the developers to keep adding more wind.”

jordan.blum@chron.com