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How Risk-Based Vegetation Management Program Slashes Costs

Jan. 23, 2023
Electric utilities have been under intense scrutiny in recent years, plagued with questions about reliability because of expansive power outages and facing potential culpability for sparking damaging fires.

Electric utilities have been under intense scrutiny in recent years, plagued with questions about reliability because of expansive power outages and facing potential culpability for sparking damaging fires.

One common thread to these issues is vegetation, whether it is trees and other plants that grow too close to transmission and distribution (T&D) infrastructure, or damage it when they are felled by wind, ice, or disease.

In fact, a recent survey of 100 utilities across the U.S. that my company and Zpryme conducted found that the top three challenges for preventing outages are budget limitations (72%), severe seasonal storms (63%); and vegetation management (56%).

Given the consequences, vegetation management is one of the most important tasks for utilities. It is not only critical for preventing outages, but also for minimizing fire risk and safeguarding the nation's power supply. And the costs could be staggering.

A McKinsey analysis suggests that through 2050, the typical U.S. utility could suffer more than $1.7 billion in costs and lost revenues due to storm damage alone, not to mention the increased risk of fire and damage to its reputation.

Cycle-Based Management Is the Wrong Approach

Utilities typically trim or cut down trees and remove other vegetation in specific areas every few years, and then do emergency work to address pressing threats at other times. But cycle-based vegetation management programs are not optimal because, in my opinion, they can be arbitrary and not address the actual risk to the infrastructure.

Trees may grow faster in some areas due to rising temperature and longer growing seasons, or drought and bug infestation may unexpectedly undermine the health of trees in or bordering rights of way (ROW). Yet, using a cycle-based approach, these problem areas may not be addressed for several years, leaving greater probability of outages and greater expense to recover.

Utilities need to tackle vegetation management more strategically, particularly since vegetation management, at 30%, is the largest non-fuel operations and maintenance cost. The cost and time involved in vegetation management, not to mention state regulations and public concern about loss of trees, all factor into decisions that utilities have to make. Plus they have to walk a fine line between controlling ratepayer costs, maximizing reliability, and minimizing risk.

From Boots on the Ground to Eyes in the Air

Breaking free from cycle-based management to focus more on the areas where risk is highest requires new technology. Many utilities are leveraging lidar surveys and beginning to use satellites. By attacking it from the air, instead of boots-on-the-ground inspections, utilities can get a new view of problem areas and better prioritize them for maintenance.

While satellites are an interesting use case, they do not provide information at a resolution vegetation managers make decisions at. Satellites can show if trees are present, and at a coarse scale even describe change over time. However, much of our nation's electric grid has a high volume of vegetation in proximity of conductors, just noting that vegetation is present does not facilitate prioritizing or prescribing work based on risk.

Survey-grade LIDAR, in our experience, is much better suited for vegetation management use because it delivers greater fidelity that provides insights into specific risks to infrastructure.

Satellites can generally show that vegetation may be impacting a certain part of the lines. But the high point densities of today’s lidar systems — anywhere from 30 to 100 points per square meter allow mapping of both vegetation and assets with enough detail that we can understand the relationship between those things with enough detail to make predictive and prescriptive calls. A data-driven, risk-based program requires knowing more than if vegetation is in proximity of conductors.

Benefits of Aerial Lidar Surveys

Looking specifically at vegetation management applications, aerial lidar surveys can provide a wealth of information, such as:

  • A comprehensive and detailed inventory of vegetation threats, classified according to their proximity to the nearest primary wire, as well as by their potential to fall-in or identify locations where vegetation is overhanging T&D infrastructure.
  • Volume analysis to provide an understanding of the tree canopies. This data provides utilities with better, more detailed guidance for trimming/removal operations than simply a tree count. Such insights can drive down maintenance costs because utilities can bid out the work out by volume, rather than general trimming and maintenance.
  • The ability to create accurate digital twins and PLS-CADD models to incorporate scenarios such as maximum operating conditions, blow-out conditions, and ice-load into risk models.
  • The ability to monitor the system for subtle changes to infrastructure, including reconductoring and tower raises, and then feed those changes back into a risk model.
  • Detailed information about the landscape, including variables such as slope, stand structure, overstrike potential, and wind-exposure that can predict the likelihood any given tree will fall & make contact with conductors.
  • Value-added analysis that provides benefits outside of the vegetation management group such as conflation of tower and span locations, and detailed hard-surface clearance analysis.
  • Creating a digital twin of utilities infrastructure to compare year-over-year, for assessing changes and ensuring that vegetation has, in fact, been removed.

Shifting Focus to Risk

Insights garnered from aerial lidar surveys have proven to be an effective way for utilities to optimize their limited vegetation management budgets. Data collected ensures that every dollar spent maximizes the amount of risk that is reduced.

Since vegetation management is one of the most important — and costly — of all tasks that utilities undertake, it’s time to look for new strategies that can help them work smarter, not harder. This is where cutting-edge technology can flip the script and help them evolve from a cycle-based program to a risk-based approach that may offer an opportunity to capitalize these costs.

Using survey-grade aerial lidar, advanced data insights, 3D modeling and predictive analytics, utilities can target vegetation management work to the areas where there is the most risk, making these efforts more cost-effective, efficient and impactful. 

Eric Merten is NV5 Geospatial’s vice president and general manager for commercial markets. He has worked for NV5 Geospatial for over 6 years. Prior to that he spent 18 years in the energy industry, holding various management positions in T&D operations, IT, capital projects and legal. He lives in Portland, Oregon.

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