Can Burying Power Lines Protect Storm-Wracked Electric Grids? Not Always

Areas with little risk of storm surge and flooding may decide that underground power lines are the best choice, if the community is willing to accept the cost. No system is sustainable if customers aren’t willing to pay for it. Differences in geography, population density, societal preferences and willingness to pay across a utility’s service area – especially in a diverse city like New Orleans – mean that no blanket policy will work everywhere.

Working with Regulators
When an electric utility wants to make changes to the grid, it needs approval from a regulator. This can take many forms.

Municipal utilities owned by individual cities make those decisions at the local government level. Cooperative, or customer-owned, utilities make those decisions through an executive board comprised of utility customers. Investor-owned utilities, which serve the majority of the U.S. population, are regulated at the state level by public utility commissions. Any discussion of grid resilience starts and ends with these agencies.

The situation in New Orleans is especially complex. Through a history of bankruptcies and reorganizations, New Orleans is the only U.S. city that regulates an investor-owned utility when a state regulator performs the same function.

This means that power company Entergy’s operations inside of New Orleans are regulated by the New Orleans City Council, while the company’s actions elsewhere across the state are overseen by the Louisiana Public Service Commission. As a result, Entergy can have distinct rates, standards for service and regulatory objectives inside and outside of New Orleans. This system allows the New Orleans City Council to focus on issues that are important to the city, but it also makes the regulatory environment more complex.

The Trouble with Transmission
The electric transmission system has several sections. High-voltage transmission lines move power over long distances from generating plants to areas of high demand, such as cities. From there, distribution networks deliver electricity to neighborhoods and individual homes or buildings.

Hurricane Ida collapsed a transmission tower carrying high-voltage power lines in Jefferson Parish, Louisiana, which is immediately west of New Orleans. This caused all eight transmission lines that supply power to the city and surrounding parishes to fail.

Hardening the transmission grid is more challenging than protecting distribution lines. Voltage is like the pressure that pushes water through a hose, so a high-voltage transmission line handles an intense flow, like a fire hose. Power is “stepped down” to lower voltages when it enters the distribution system, so the power moving through a distribution line is analogous to water flowing through a garden hose.

Burying transmission lines is technically feasible, and may be practical over short distances. But all power lines lose some of the electricity they carry as heat – and if this heat builds up, it ultimately restricts the line’s ability to carry power over longer distances. Air effectively dissipates heat from above-ground lines, but buried lines are more vulnerable to heating.

Relocating transmission lines or building extra lines as backups may be the only options for strengthening the system in many places. But building new high-voltage power lines is challenging.

Many people are concerned about possible health risks from exposure to electromagnetic fields, which emanate from high-voltage lines. Regulatory agencies struggle with finding acceptable sites and allocating the costs of these projects.

Investment in the U.S. transmission system has increased over the past 15 years, but more is needed. The Grid Deployment Authority proposed in the bipartisan Infrastructure Investment and Jobs Act would address some of the challenges of transmission line siting, but other hurdles will remain.

Managing Expectations
Whatever steps utilities take to harden the grid, there still are circumstances when the power will go out – especially during climate-driven disasters like wildfires and tropical storms. It’s easier to talk about making the power grid more resilient soon after disasters, but the conversation needs to continue after power is restored. In my view, the only way to solve this challenge is by finding ways for utilities, regulators, businesses and customers to transparently discuss the most feasible ways to keep the lights on.

Theodore J. Kury is Director of Energy Studies, University of Florida. This article is published courtesy of The Conversation.