A North American grid for a Spanish-American republic
By a regulated optimist who grades in pencil, votes with both hands, and still believes maps should tell the truth.
I. Prologue: a border made of copper and light
ost borders are written in ink, but the U.S.–Mexico line is increasingly drawn in wire. It is a thin set of bridges—high-voltage interties, converter halls, relay cabinets—that allow two different electrical civilizations to borrow from each other when heat climbs, when hurricanes prowl, when a gas plant blinks at the wrong second. Stand near the Sharyland "Railroad" DC tie outside McAllen and you can hear the hum of cooperation, 300 megawatts wide. It is the sound of neighbors pretending they are not.
What follows is not a daydream about continental super-grids. It is a practical brief for expanding the handful of interconnections we already have; planning for cross-border power like adults; and using the 2026 USMCA review to bake neighborliness into the operating code of North America's energy system. The payoffs are reliability, decarbonization, and courtesy—the three pillars of a modern republic.
II. The map, honestly: tiny bridges, outsized stakes
Despite the romance of scale, U.S.–Mexico electricity trade is tiny: in 2024, imports from Mexico supplied roughly 0.1% of U.S. consumption (about 6.0 TWh), while exports to Mexico totaled 1.7 TWh. Yet that decimal can be decisive at the margin—during heat waves, freezes, or local outages. Think of it as a pressure valve on a sealed pot.
The present electrical border has three anatomies:
1. ERCOT↔CENACE DC ties (Texas):
- Sharyland "Railroad" tie, Mission, TX—300 MW after a 2014 expansion (two 150-MW back-to-back HVDC units).
- Laredo VFT—100 MW, a variable-frequency transformer link.
- Eagle Pass HVDC Light—36 MW (often used for emergencies; outaged for stretches after 2020).
Together, these let Texas send or receive a few hundred megawatts with Mexico's northeast grid—small in percentage terms but powerful when minutes matter.
2. CAISO↔CENACE (Baja California Norte):
Baja Norte is an electrical island not connected to Mexico's main grid; it is tied into California at Otay Mesa and Imperial Valley (the WECC Path 45 interfaces). CAISO and Mexico's grid operator CENACE have explored market integration for Baja Norte (EIM), precisely because these ties exist and geography begs for coordination.
3. WECC↔Sonora (proposed):
The Nogales Interconnection—a bi-directional back-to-back HVDC link at a proposed Gateway Substation west of Nogales—won federal reviews and a Presidential Permit envisioning up to 300 MW in two 150-MW phases. As of 2025, parts of the project are on hold, a parable about how hard it is to build the obvious.
Across these bridges travel not just electrons, but options: emergency support, renewable balancing, fuel-diversity hedges. And yet we treat them as curiosities. That is a governance failure, not an engineering limit.
III. Why this matters now (load growth, law, and opportunity)
Three clocks are chiming at once:
Load is surging. Data centers, electrification, and weather volatility push U.S. demand to record highs in 2025–26. We will need every lever of flexibility we can lawfully grab.
-
The transmission rulebook changed. In 2024, FERC's Order 1920 required 20-year regional planning and clearer cost-allocation; Order 1977 revived limited federal siting in National Interest Electric Transmission Corridors (NIETCs); DOE updated 216(h) to coordinate federal authorizations. Translation: the U.S. finally has a scaffold to plan big wires—and that scaffold can and should consider cross-border options.
-
USMCA's review lands in 2026. Article 34.7 forces a six-year joint review. Mexico and Canada launched public consultations in 2025; the docket is opening. If we want a North American Energy Annex that treats interties as shared infrastructure, this is the window.
The punchline: policy is finally aligned to plan, permit, and finance the unglamorous nerve tissue of a continental grid. Time to use it.
IV. Case studies in miniature (what the ties already proved)
1) The border as a safety belt (Texas)
ERCOT's DC ties to Mexico are small but surgical—300 MW at Sharyland, 100 MW at Laredo, 36 MW at Eagle Pass—originally justified as emergency valves. In winter storms and extreme heat, they've supported voltage and capacity when local reserves were tight. They also create optionality: bilateral assistance without synchronizing the entire grid. (Think pressure-equalization between two rooms.)
2) Desert wind with a passport (California/Baja)
Cross-border lines like Energía Sierra Juárez move wind from Baja's mountains into San Diego County under DOE Presidential Permits, riding the Imperial Valley–Miguel corridor. That project's EIS reads like a dry epic: lattice towers, monopoles, import limits, and the patient translation of terrain into policy. This is what neighborly decarbonization looks like: mundane, permitted, effective.
3) Nogales, the nearly-there classroom (Arizona/Sonora)
The Nogales back-to-back HVDC plan—150 MW now, expandable to 300 MW—would give southern Arizona and northern Sonora a two-way safety valve and economic bridge. It cleared environmental review and permitting; the utility's own site now says portions are on hold. Lesson: coordination is infrastructure. Projects die not for lack of steel, but for lack of clock management across agencies, landowners, and politics.
V. A solar-punk grid, but make it municipal (design rules that don't lurch)
We do not need a visionary poem; we need a workbook. Here are seven rules jurisdictions can execute in the next 24 months.
1) Put cross-border options into the required plans
Order 1920 forces 20-year planning in each region; tell your RTO/ISO to model interties as resources with quantified reliability and production-cost benefits. Use DOE's NIETC process to align corridors with real congestion, then pair with 1977 backstop siting as the last resort—not the first headline.
2) Write an Energy Annex into the USMCA 2026 review
A narrow chapter can do three boring, transformative things: (a) expressly coordinate transmission planning assumptions across CAISO/WECC, ERCOT, and CENACE; (b) standardize data sharing (outages, interchange limits, seasonal assessments) at the operator level; (c) fast-track Presidential Permits with reciprocal timelines and public dashboards. Mexico and Canada already opened consultations; send this in, with maps.
3) Double the Texas–Mexico transfer by 2028
Add 100–200 MW at Laredo (VFT expansion), harden Eagle Pass, and study a second HVDC site in the Lower Rio Grande Valley. This is not a moonshot; it is a three-project program piggybacking existing sites and rights-of-way. (Sharyland already showed how to go from 150 → 300 MW.)
4) Make Path 45 do more than whisper
At the California–Baja interfaces (Otay Mesa, Imperial Valley), finish the homework for Baja Norte to participate in Western real-time coordination on a regular basis. CAISO and CENACE scoped this years ago; dust off the MOU, modernize telemetry and scheduling, and treat Baja wind as capacity you can count, not just curtail.
5) Resurrect Nogales with a transparent clock
Take the Gateway back-to-back from "on hold" to "in service" by committing to a public Gantt: land, funding, procurement, commissioning. If a bi-national project dies, let it be for reasons named in both languages. (DOE's 216(h) coordination rule exists for exactly this kind of knot.)
6) Bilingual trust as an engineering control
Run cross-border transmission engagement like an airplane checklist: Spanish/English notice templates, staffed hotlines on both sides, right-of-way benefits published parcel-by-parcel. The fastest path through litigation is comprehension. (And no: an English-only posting at a Spanish-speaking right-of-way is not compliance; it's an invitation to delay.)
7) Buy flexibility in small, repeatable pieces
While the lawyers debate megaprojects, fund utility-scale battery nodes at the interties themselves and standard curtailment-sharing agreements. A 50–100 MW/200 MWh battery at an HVDC site turns a bridge into a reservoir.
VI. Economics without poetry (why the math pencils)
Reliability insurance. A few hundred MW of firm import capability during scarcity has an outsize value—far above average day-ahead prices. The ERCOT–Mexico ties already operate this way; intentionally right-sizing them is cheaper than building peaker fleets that sit idle 350 days a year.
Renewable integration. Baja Norte wind and solar don't peak exactly when Southern California does. Interties convert geography into diversity—the oldest portfolio trick in the book. CAISO's own planning artifacts treat Path 45 as real; it's time the policy caught up.
Trade reality. U.S.–Mexico energy trade value whipsaws with prices; the physical electricity flows are small but rising. Treat the 0.1% as a floor, not a design constraint. When EIA reports that imports and exports ticked up in 2024, it's a nudge: the channel exists; deepen it carefully.
VII. Law as a tool belt (how to actually get steel in the ground)
-
Use 1920's state-engagement window. States now have a six-month seat inside regional planning cycles; bring cross-border upgrades as candidate projects with quantified multi-benefits (reliability, resource adequacy, production cost). RMI, NASEO, and NYISO primers explain the choreography if your staff is new to this dance.
-
Queue NIETCs where the physics hurts. DOE's NIETC page and FERC's 1977 materials lay out the path; align cross-border stubs with domestic congestion relief so federal finance and backstop siting are possible, even if never used.
-
Modernize the Presidential-permit playbook. DOE keeps the permit roster; legal analysts in 2025 flagged proposals to streamline cross-border permits and export authorizations. Bake timelines and public trackers into your application strategy; don't let process ambiguity be the project killer.
VIII. The hemisphere inside the wires (culture is a grid, too)
This is Sol Meridian, so let's say the quiet part in two languages: a Spanish-American nation that refuses to wire itself to its neighbors is committing a category error. Our demography speaks Spanish at home; our economy already trades massively in fuels and parts with Mexico; our politics insists on reliability. Interties are not an exotic flourish; they are the infrastructure of courtesy—the habit of planning together so that neither party must beg in a crisis.
There is also a literary pleasure here. If Borges taught us to love mirrors, an HVDC back-to-back is a mirror that adds. Two asynchronous systems face each other across a converter hall and decide, every second, to be generous. That's what a republic ought to feel like.
IX. Three small scenes (because policy is a place)
Mission, Texas, 4:03 p.m., a heat advisory
The dispatcher watches the Sharyland dashboard step up from 180 to 260 MW import. A nurse across town never knows; her clinic's AC does not blink. The border hums; a blackout somewhere else does not happen.
Otay Mesa, 10:11 a.m., marine layer lifting
A gust crosses the Sierra de Juárez; a wind farm's output nudges into the Imperial–Miguel corridor. A planner in Sacramento sees five-minute prices relax and writes a note: "Path 45 earned its keep."
Nogales, twilight
A utility lawyer reads the Gateway file and circles a word: "on hold." She opens a new document titled Relight and writes two columns—"what we control," "what we don't"—in English and Spanish. The first list is longer than anyone expected.
X. Epilogue: make the border boring
In the next edition of our national story, the interties will be so normal we won't bother to name them in speeches. That's the victory: a border that stays dramatic for poets and boring for engineers—planned in 20-year cycles, reviewed under USMCA, financed with NIETCs and state compacts, explained in two languages, operated by people who think electrons should not need passports, only standards.
If we do that, the sun we share will set a little less wastefully, and the line on the map will feel less like a wall than a wire—thin, audible, generous.
Sources (validated)
- U.S.–Mexico electricity trade share (2024) and volumes: EIA Today in Energy (imports ≈ 6.0 TWh, exports 1.7 TWh; ≈ 0.1% of U.S. consumption)
- ERCOT↔Mexico DC ties (capacities & function): ERCOT DC-tie ops docs; Hitachi Energy/Sharyland project notes; AEP/ABB announcements; analysis of tie roles post-Uri
- Baja Norte isolation & CAISO interfaces (Path 45); EIM exploration: CAISO/CENACE briefing (Baja Norte connected at Otay Mesa & Imperial Valley; not linked to Mexico's main grid)
- Energía Sierra Juárez & DOE permits/EIS: DOE EIS and supplemental documents describing cross-border line to Imperial–Miguel segment
- Nogales Interconnection (permit & status): DOE/FR notices (bi-directional HVDC, 2×150 MW phases) and UniSource updates indicating on hold
- Load growth outlook: Reuters summary of EIA record demand projections for 2025–26
- Transmission law & process changes: FERC Order 1920 explainer and 1920-A; Reuters coverage; DOE NIETC designations; FERC staff presentation and Order 1977 analysis; DOE 216(h) coordination rule
- USMCA Article 34.7 review (2026) and 2025 consultations: Wilson Center guide; CSIS brief; Reuters on Mexico & Canada consultations
This is the sixteenth in the Sol Meridian series exploring the hidden continuities that shape American public life. A technical and policy analysis of U.S.-Mexico electrical grid cooperation as a foundation for North American energy integration.