Why Don’t We Just Bury Every Electrical Line Underground?

As Atlantic hurricane season nears its end, those unfortunate enough to live in the path of extreme weather may wonder why their power lines aren’t buried underground, given how ly they are to sustain storm damage.

Indeed, undergrounding high-voltage lines can yield some compelling benefits for electric utilities. Trees and vegetation, responsible for the majority of overhead line disruption, are completely taken out of the equation. Underground lines are protected from severe weather, including high winds, lightning, and ice. And in regions that experience wildfires, undergrounding lines is a reliable way to prevent wildfires caused by sagging or broken lines. Utility customers mostly care about service reliability, so undergrounding lines can also improve customer satisfaction.

So why don’t we just put every power line underground? Mainly because someone has to pay for it, and that someone is typically the customer. This puts utilities in a tricky spot: they must decide where undergrounding is most beneficial while balancing the cost of system upgrades that ratepayers would have to pay for. A utility could underground every line in its service territory, but the resulting rate increases could be a public relations catastrophe, since most customers won’t care how reliable their electricity is if they can’t afford to pay for it.

recent examples

PG&E’s 10-year electrical undergrounding plan

Earlier this month, Pacific Gas and Electric Company (PG&E) filed a proposed 10-Year Electrical Undergrounding Plan (EUP) with the California Office of Energy Infrastructure Safety (Energy Safety), outlining a long-term, risk-based strategy intended to improve safety and reliability in high wildfire-risk areas across Northern and Central California. PG&E argues the plan would deliver long-term benefits valued at $117 billion.

The proposed plan would bury about 5,000 miles of electric distribution lines from 2028 to 2037 in areas where undergrounding is expected to reduce wildfire risk most. In these areas, it can reduce ignition risk by nearly 98% and improve reliability with 90% fewer outages, PG&E said. The utility estimates the $11.4 billion plan will customers $6 billion in vegetation management, operations, and maintenance costs over the life of these assets. The plan includes work in more than 30 Northern and Central California counties.

“Placing powerlines underground provides the most effective way to reduce wildfire risk and enhance reliability for customers within High Fire-Threat Districts,” said Peter Kenny, PG&E chief delivery officer and electric transmission and distribution senior vice president. “A 10-year plan allows us to develop and execute projects with increased efficiency, which translates into cost savings for customers, all while delivering enhanced safety and reliability to the hometowns we are privileged to serve.”

Over the last few years, PG&E has reduced its undergrounding cost per mile by approximately 25%. A key feature of the plan is PG&E’s use of advanced data analytics and risk modeling to forecast where undergrounding will provide the greatest benefits for customers and communities. The company’s risk-based approach considers wildfire lihood and consequence, system reliability, customer impacts, project costs and benefits, and how undergrounding compares with other wildfire mitigations.

CenterPoint Energy’s Greater Houston Resiliency Initiative (GHRI)

Over the summer, CenterPoint Energy announced it reached a key milestone as part of its Greater Houston Resiliency Initiative (GHRI), with more than 500 miles of power lines strategically hardened across Greater Houston and is on track to reach its goal of hardening 750 miles of power lines by the end of 2026.

Hardening power lines involves strengthening and upgrading key equipment, including poles, wires, and transformers, to better withstand extreme weather and improve reliability. To date, CenterPoint has hardened more miles of power lines than the distance from Houston to Midland. As part of its overall commitment to build the most resilient coastal grid in the nation and improve day-to-day reliability, CenterPoint’s GHRI efforts have included installing 75,000+ stronger poles and 750+ automation devices. and undergrounding 850+ miles of power lines.

How much does Undergrounding Really cost?

The cost of undergrounding a line varies widely, depending on the type of line (distribution vs. transmission) and its physical location. For example, undergrounding a distribution line in a new development is much cheaper than undergrounding a line in a dense urban environment.

According to a U.S. Department of Energy (DOE) report, undergrounding transmission lines typically costs more than distribution lines, with new construction roughly 3 to 10 times more expensive and conversions 1.5 to 5 times more costly.

Costs vary by utility, too. PG&E’s distribution undergrounding costs, including work in both urban and rural areas, are around $2.97 million per mile. CenterPoint Energy estimates its Greater Houston Resiliency Initiative has a price-per-mile of $7 million. By comparison, Wisconsin Public Service Corporation paid $0.16 million per mile to bury some of its rural distribution lines.

California utilities PG&E, Southern California Edison (SCE) and San Diego Gas & Electric (SDG&E) say the costs for undergrounding existing overhead distribution infrastructure can range from $1.85 million to $6.072 million per mile. For transmission, those utilities say the cost for constructing new overhead lines ranges from $1 million to $11 million per mile, compared to $6 million to $100 million per mile to convert existing overhead transmission to underground.

The California Public Utilities Commission (CPUC) also broke down what it would potentially cost to put every line in the state underground. California has approximately 25,526 miles of transmission lines, and approximately 239,557 miles of distribution lines, of which approximately 147,000 miles of distribution lines are overhead. With an average cost of $3.8 million per mile to bury distribution infrastructure across all three utilities, ratepayers would need to pay $559 billion to convert all 147,000 miles of overhead distribution in the state. The cost of burying all 34,000 miles of overhead transmission lines in the state would be $204 billion, assuming an average cost of $6 million per mile.

The Edison Electric Institute found that undergrounding costs, on average, $600,000 to $13 million (2019 US dollars) for distribution and $1.5 million to $33 million (2019 US dollars) for transmission.

Underground Arizona, a non-profit advocacy group, argues that for every $10 million in underground expenses a utility undertakes, ratepayers see a 0.003% increase in rates. The group also argues that under the best-case scenario, undergrounding lines actually s ratepayers money by reducing upfront land costs and long-term maintenance and repair costs. Additionally, Underground Arizona asserts that underground assets can be three to seven times cheaper to maintain than overhead lines, while lasting two to three times longer.

ing a huge winter storm in the early 2000s, a study by the North Carolina Utilities Commission and the state’s Natural Disaster Preparedness Task Force found that burying every distribution line in the state would increase bills by over 125%.

When are ratepayers willing to pay for undergrounding?

A ratepayer’s recent experiences can greatly affect their willingness to pay for undergrounding costs. A research article published in 2024 indicated that willingness to incur private costs for climate adaptation burying power lines increased in correlation with the frequency of outages in the last 12 months and property damage from extreme weather events within 200 miles. Interestingly, the report also found that framing undergrounding as an essential good for decarbonization through electrification actually reduces support for undergrounding.

The Edison Electric Institute (EEI) conducted a poll in 2012 which found that 60% of electric customers were willing to pay up to 10% more on their electric bills for undergrounding, and another 11% were willing to pay up to 20% more. Fewer than 10% of polled customers said they were willing to pay more than a 100% increase.

CenterPoint Energy said its $2.9 billion resiliency efforts will lead to an additional $1 on each customer’s monthly bill this year, slowly increasing to $4 per month by 2028.

Anaheim, California, has been slowly burying every overhead line in its system since the 1990s: a 4% surcharge on customer bills is funding a 50-year undergrounding effort that involves 240 circuit miles. The city is spending about $15 million per year to fund the project, with a price between $2.8 million and $4.6 million per mile depending on the location. Spreading the project out over decades has helped ease the burden on ratepayers, but 50 years is a long time to wait for resiliency. Thus, utilities are faced with the decision of whether to speed up undergrounding efforts with a larger impact on individual bills, or take a slower approach to massage the price out over a longer period of lower bill payments.

Another factor affecting customers’ willingness to pay has nothing to do with reliability. Suburban neighborhoods may see overhead lines as unsightly and are willing to pay more to simply keep the lines out of view. A study in Japan found that some households would be willing to pay the equivalent of $30 to $60 more per month to avoid overhead lines in their neighborhoods.

Each utility considering undergrounding must balance reliability and affordability carefully. Is speeding up an undergrounding project worth the financial burden on ratepayers? Is slowing down an undergrounding project to ease the cost worth the wait for resiliency? How many outage minutes are customers willing to suffer through each year? And does the cost of fixing that problem outweigh the benefits customers will experience?