After nearly two decades of permitting battles, federal interventions, and legal challenges, a 550-mile transmission line across the southwestern U.S. will finally begin commercial operation at the end of this month.
The $11-billion SunZia project is one of the first major regional transmission lines built in a generation. Paired with the 3.5-gigawatt SunZia wind farm — which has faced its own share of problems — the new high-voltage direct current line was designed to transport up to 3 GW of clean energy from central New Mexico to millions of homes in southern Arizona and California.
Getting the line built was a slog. The project ran into nearly every kind of challenge that makes large transmission builds so slow: federal land reviews, military airspace conflicts, environmental opposition, and multi-state permitting coordination. It was built in part by Pattern Energy, a large independent renewable power developer that also built the SunZia wind project. But its success is largely thanks to a little-known quasi-public entity that the New Mexico legislature created in the early 2000’s: the state transmission authority.
The pitch for state transmission authorities is relatively straightforward. They’re designed to bridge the gap between government and the private sector to get transmission projects built more quickly. In the West, without regional transmission organizations to plan and socialize the costs of big lines, transmission often gets built piecemeal, and cost-allocation fights can stall projects for years.
To combat this, bodies like New Mexico’s Renewable Energy Transitional Authority partner with private developers to plan, finance, and build lines, smoothing the way with a unique toolkit that includes tax advantages, eminent domain authority, and a reduced regulatory burden.
Now, as the region works to weather the collision of surging electricity demand from data centers and ambitious state-level clean energy mandates, other states are looking to replicate it in the hopes of giving a boost to their own ambitions of building large grid infrastructure. Exactly how far the transmission authority template could spread, however, remains an open question. While the lack of an RTO intensifies the need for a transmission authority, the existence of one doesn’t necessarily diminish an authority’s impact; New Mexico’s RETA, for example, has already developed one transmission line inside the SPP footprint, a project awarded as part of the RTO’s standard process.
New Mexico’s new map
Transmission authorities like New Mexico’s aren’t state agencies, but they aren’t private sector entities either. They’re somewhere in between, designed to look like a governmental entity and with key abilities to reduce the financial and developmental risk of big transmission projects, but with more flexibility to enter into contracts with private partners.
New Mexico created RETA to unlock the export potential of the state’s wind and solar resources, explained executive director Lynn Mostoller, potential that has been long restrained by an aging grid that wasn’t built to provide access to the best renewables sites. The authority leverages a structure that involves signing a memorandum of understanding with a developer, acquiring the line and co-developing it alongside the private company, and then ultimately leasing or selling the line back to either the developer or a utility. It is funded through state appropriations and fees from its project partnerships, rather than ratepayer charges.
In the years since it was established, RETA has helped shepherd two major projects in addition to SunZia — including one line upgrade and one new build line — from concept to construction by partnering with merchant developers, offering tax advantages, assembling land using permissions, and guiding projects through state regulatory hurdles.
Western Spirit, a 155-mile, 455-kilovolt line that went into service in 2021, was RETA’s first major success. The authority co-developed the line with Pattern and then sold it to New Mexico’s largest investor-owned utility, Public Service of New Mexico. The cost of the sale was borne by the wind farms slated to use the line to send electricity, keeping it out of PSNM’s rate base and off consumer bills.
Today, RETA has signed at least six MOUs with transmission developers for projects across the state. Among them is a 137-mile line in SPP territory with NextEra designed to connect substations in the eastern part of the state for greater resiliency, and North Path, a 400-mile project with Invenergy expected to come online in 2032.
If all of its currently planned projects are built, RETA’s portfolio would add more than 16 GW of transmission capacity to the state’s grid — nearly four times New Mexico’s current peak load.
SunZia is RETA’s crown jewel: a marquee regional line and part of the largest renewable energy development project in the western hemisphere. But it’s also a cautionary tale about how long it still takes to build big transmission lines, transmission authorities or no.
That’s partly due to changing political winds. RETA was established in 2007 under New Mexico’s then-governor Bill Richardson, a former energy secretary and one-time presidential candidate who pushed an aggressive vision for the state’s clean energy resources. But Richardson’s successor, Republican Gov. Susana Martinez, who served from 2011 to 2019, was significantly less enthusiastic. Under her tenure, state funding for the authority was gutted, and dropped to zero for several years running. RETA was left essentially dormant, running on project fees to continue ongoing permitting processes.
Even now, though RETA is now funded and back on firmer footing, the shifting federal attitude toward renewables projects, particularly wind projects, has made it harder for the authority’s private partners to get the new generation that would use those lines permitted.
“If the obvious customers [for a line] were wind generation customers, that’s probably not going to happen until there’s a new administration in place,” Mostoller explained. “That’s definitely slowing us down a little bit on some projects, but we also have projects at earlier stages that weren’t planning on being completed until well after 2028 anyway. So they’re just doing their thing, and we’re keeping on.”
A model for the West
The history of transmission authorities in the U.S. actually spans more than two decades, since several years before New Mexico established RETA in 2007. Wyoming established the country’s first transmission authority in 2004, dubbed the Wyoming Infrastructure Authority. It was modeled after the state’s Pipeline Authority, designed to facilitate fossil gas pipeline projects.
A handful of other states, including the Dakotas, Idaho, and Kansas quickly followed suit, all creating their own state-level authorities that could plan corridors, secure financing, and even own and operate high-voltage lines. Each had a slightly different mandate. Some were restricted to transmission only; others could support generation too; and New Mexico’s authority can only get involved with projects that source at least 30% of the energy from renewables.
At least legislatively, the transmission authority experiment seemed well underway. But then there was a lull when they were void of action for several years, driven by the 2008 financial crisis, a prolonged stretch of flat electricity demand, and the simple fact that most of the early authorities had yet to produce visible results. Wyoming’s infrastructure and pipeline authorities merged, creating the Wyoming Energy Authority, which supports projects ranging from oil, fossil gas, and coal to solar, geothermal, wind, and critical minerals. In Kansas, the authority’s work was transferred to the state Corporation Commission.
In the late 2010s and early 2020s, though, tighter clean energy mandates and clear federal signals caused a renewed uptick of interest. Colorado was the first state to return to the work, creating its Electric Transmission Authority in 2021.
CETA is modeled heavily on New Mexico’s authority, explained executive director Maury Galbraith, though there are a few key differences. For one, CETA is generation-agnostic and can support fossil generation-related transmission if that’s what’s needed for reliability. Also, Colorado isn’t likely to build out an export machine on the scale of New Mexico’s; instead, most of the new transmission CETA helps build will be aimed at serving in-state load.
And Colorado’s authority is just starting to get off the ground. “We’re still a startup,” Galbraith said. Among CETA’s first tasks was to conduct a statewide transmission study, which identified 45 projects needed across the state. From there, CETA ran a six-month stakeholder process to narrow that list down to six regional lines where regulatory or market barriers are preventing utilities from acting on their own.
All six projects, which were approved by CETA’s board in mid-2024, are in the very early, conceptual stages. Among them is a new line from Fort Collins north to Cheyenne to relieve a historically congested path and tap Wyoming wind power, and an east-west line to move power from the state’s less-populated Western Slope across the Rockies to the Front Range.
The next key hurdle, Galbraith explained, is figuring out how best to finance and advance those plans into buildable projects. Part of that involves deciding how to leverage CETA’s revenue bonding authority, meaning bonds that would be repaid from project revenues rather than the state’s general fund.
Transmission authorities for the AI era
In the early days, transmission authorities were originally created to help resource-rich states export wind, coal, and fossil gas to distant load centers. But the rapid data center buildout driving up national energy demand is making transmission investments ever more important, and the authority structure is finding new relevance.
According to Ava Gallo, climate and energy program manager at the National Caucus of Environmental Legislators, a central transmission planning authority can help states outside RTOs respond to that growing demand more quickly, while also ensuring public input and environmental review aren’t totally sidelined in the rush to build.
That’s the framing of the Washington bill establishing that state’s electric transmission authority, enacted in March. Pressure from data centers and rising load combined with clean energy goals are a central topic in conversations with legislators across the West, explained the bill’s sponsor, freshman state Sen. Victoria Hunt (D). While Washington was the only state to get legislation over the finish line this session, Montana, Nevada, and Oregon are all exploring the idea as well. NCEL is expecting a new round of proposals when legislators return for full term next year, and Hunt said she’s in active conversations with transmission authority-curious lawmakers from neighboring states.
Washington’s legislation draws on lessons from laws that predate it around the country, and involved a bipartisan negotiation process, Hunt added. Eminent domain authority was one of the more sensitive sticking points. “That was definitely one of those issues that raised concerns, and then we took some of that feedback and made adjustments,” Hunt explained. The final legislation was written to make clear eminent domain would be a tool of last resort.
Hunt is clear-eyed about the limits of transmission authorities, which should be viewed as a tool for the buildout demanded by load growth, rather than a silver bullet, she said. Legislators must consider how much of their state’s problems an authority would address, versus how much will ultimately come down to permitting reform, for example.
For now, Hunt’s focus is on Washington’s own deadlines. The state’s Clean Energy Transformation Act requires greenhouse gas neutrality in electricity supply by 2030, and 100% emissions-free electricity by 2045.
“Already we’re seeing, in trying to meet increased demand, this move towards fossil fuels, and that’s not going to be possible under our current law,” she said. “That’s another reason why we need to make sure we have transmission — make sure we have a way to actually meet that goal by connecting our renewable projects.”
