ERCOT already operates a power system as large as those in several European countries, but demand growth is expected to bring it up to the level of PJM and MISO, which has the industry considering building a new system of 765-kV lines to transmit power around Texas.
“When you think about PJM’s high-voltage overlay, they have this huge 765- and 500-kV system to move power back and forth and back and forth,” Grid United President Kris Zadlo said on a webinar March 13 hosted by Americans for a Clean Energy Grid. “And I think that’s kind of what we need to start thinking about if we’re going to be going to such a large system.”
In the next decade, peak demand could double on ERCOT’s grid while overall consumption of power triples, said Michael Webber, professor of mechanical engineering at the University of Texas at Austin.
The new demand is being driven by different factors. Data centers are part of the picture, but other sources include the need to electrify more of the oil and gas production in the booming Permian Basin and keep up with the general population and economic growth in Texas. ERCOT has grown 1 to 2% per year recently, when much of the rest of the country grew little to none, but now growth rates are up to 3 to 4% annually, Webber said.
CenterPoint Energy is forecasting that demand in and around Houston will grow by 10 GW, which is the equivalent of adding Belgium’s total power demand to the system.
“So, we have to add a Belgium to Houston, but we also have to add a Belgium to West Texas, and maybe half of Belgium to Abilene for data centers, or whatever,” Webber said. “If you start to add it up, and maybe a 10th of a Belgium here and there for LNG export terminals, which all say they’ll be electrified … it’s a lot of demand.”
If all the demand were in one part of Texas, it could be met by building one power plant, but given how spread out it is across the state, transmission needs to be part of the picture, Webber said.
“All of this adds up to this new estimate of 150 GW of load coming down the pipe,” said Conservative Texans for Energy Innovation’s Michael Jewell. “When the legislature heard about that, I think it really kind of freaked them out and got them to say, ‘You know, maybe there really is something that needs to happen.’ And I think it really has changed the dynamic to, ‘We do need to think about, how are we going to address this?’”
Building transmission is part of the answer, but policymakers could decide to stick to 345-kV lines, as they did when Texas last did a major buildout of transmission more than 15 years ago with the Competitive Renewable Energy Zone lines to bring wind to customers.
“One of the early questions was, should we be looking at 500-kV lines?” Jewell said. “And that kind of fell to the wayside as the advantages of 765 and the greater ability to move power there kind of outweighed almost what one could think of as an interim step in that regard.”
The idea of building out 765-kV lines was first broached in the legislature with the aim of helping Permian Basin drillers continue to electrify, but once the focus was widened to the entire state, 765 kV only made more sense, he added.
While 765 kV is the largest voltage used in the U.S., China has built an overlay system with 1,100-kV lines, Webber said. Voltages that high start to come up against manufacturing issues, Zadlo said.
“Once you go above 345, whether it’s 500 or 765, it’s the same thing,” Zadlo said. “My understanding is the 765 breakers come out of the same factories that are making 345 breakers. So really, there’s no difference there. I think the only big difference is when it comes to transformer production.”
Building a series of 765-kV lines also takes about the same amount of time as building 345, he added.
Forecasting demand growth always comes with uncertainty, but given that some of the new loads can come online in a year while power plants take three or four, and transmission in Texas takes at least six, it makes sense to start planning for it now, Zadlo said.
“You can’t accelerate a transmission line, right? You just can’t,” Zadlo said. “It’ll be disastrous if we’re wrong; if we don’t build that line on time. … But you can always slow it down if the load doesn’t materialize. You can always pull back the plans.”
Another reason to move with big infrastructure buildouts is that they are almost always used to their capacity, Webber said. Railroads, broadband, the highways and other historical examples all involved some overbuilding, with only massive technological changes like the advent of automobiles and highways making the railroads less useful a century later.
“If you’re going to go to the trouble [of building] capacity, you might as well build more capacity, and the higher voltage gives you more capacity,” Webber said. “So, I’d argue that this is actually the American way of doing things, and it would just give us more ability to move things around.”
