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Managing T&D Systems During More Severe Weather

Aug. 10, 2021
Vegetation management is key to success.

For utility vegetation management professionals, the impacts of increasingly extreme weather are many. CO2 concentrations have been steadily rising for more than two centuries, which affects how plants photosynthesize, resulting in increased plant water use efficiency, enhanced photosynthetic capacity and increased growth.

Further, increases in temperature raise the rate of many physiological processes, such as photosynthesis in plants, to an upper limit, depending on the type of plant species. A climate that is drying in some areas and growing wetter in others also leads to extreme weather events such as heat waves, droughts, hurricanes, blizzards, ice storms, thunderstorms and tornadoes – all words that bring a shudder to electric utility managers.

Simply put: The impact of climate change on utility vegetation management (UVM) programs is profound, and it is happening right now. Regions that have recently dealt with extreme weather events and wildfires (California, Colorado, Oregon, Texas, Louisiana, and most of the southeastern states) understand their vegetation management protocols must adapt to climate impacts. Those that have been spared such catastrophic events thus far should be planning for them now.

But what are the specific ways that climate impacts electric utility infrastructure? And how can UVM professionals adjust their strategies in managing for both routine maintenance as well as catastrophic events?

Impacts from climate change are happening now, affecting ecosystems and communities in the United States and around the world. Here are some of the specific impacts on energy systems:

Carbon Dioxide
Carbon dioxide (CO2) is a greenhouse gas that absorbs and radiates heat. While carbon dioxide serves an important role in making our environment habitable, increases in greenhouse gases have tipped the Earth's energy budget out of balance, trapping additional heat and raising Earth's average temperature, which affects how plants photosynthesize. As temperatures rise, and growing seasons lengthen, plant growth increases correspondingly. Utility vegetation managers may find that current budgets and management technics are not sufficient to maintain vegetation safely and reliably.

According to the NASA Goddard Institute for Space Studies, 2020 was the hottest year on record effectively tying 2016, the previous record. Increases in temperature raise the rate of many physiological processes, such as photosynthesis in plants, to an upper limit, depending on the type of plant species. This could create longer growing seasons and an increase of re-growth when there is adequate rainfall. Increased plant growth could well have multiple impacts on a utility’s vegetation management program, including adjustments to cycle lengths and clearance requirements, and greater potential for tree-to-conductor contacts, resulting in outages and fire ignitions.

As Earth’s climate has warmed, a new pattern of more frequent and intense weather events has unfolded around the world. Scientists agree that climate change has made hurricanes more intense. It has also led to an increase in heat waves, droughts, blizzards, ice storms, thunderstorms and tornadoes. 

The impacts of extreme weather events on utilities include:

  • As atmospheric moisture increases due to the greenhouse effect, hurricanes also increase in intensity and frequency, causing catastrophic damage to utility infrastructure.
  • Drought conditions increase tree mortality, resulting in greater volumes of hazard trees.
  • Droughts result in a higher potential for wildfires, which pose a significant threat to electric transmission and distribution facilities.

Goals and Objectives
So, what can utility vegetation managers do about these significant changes to the environment? As mentioned earlier, many states and utilities are already dealing with the devastating effects of climate change. Now is the time for all utilities to prepare for climate change’s impacts to their systems, particularly from a vegetation management perspective.

UVM professionals need to adjust program goals in the following ways:

  • Safety: Workload is going to increase for the vegetation management workforce, who are in short supply as it is. Activities like hazard tree mitigation, clearing vegetation/conductor contacts, and storm restoration will most likely increase due to climate change. Therefore, employee and contractor safety protocols will become ever more important. Safety training, proper equipment, and adequate supervision will be imperative. Safety standards and procedures may need to be revised due to an increase in hazardous situations. 
  • Quality control: Quality of work may decline due to the increased workload. As labor resources become even more difficult to acquire, adequate training in work standards, as well as proactive supervision, will be critical to achieve and maintain professional work.
  • Maximize productivity: Workforce productivity must be maximized. With a likely increase in workload, and potential shortages in labor and equipment, activities such as pre-inspection, customer notification, work planning, crew training, crew type selection, travel time, debris disposal, work verification and supervision must be fine-tuned to maximize productivity. Productivity metrics should be established to drive excellent performance through times of high productivity.    
  • Measure risk: Vegetation-caused interruptions and ignitions will most likely increase in a changing climate. Metrics for these events may need to be re-established based on the level of service and risk the utility will accept. For example, in wildfire-prone areas, a zero-ignition objective may be necessary due to the level of risk.
  • Increased and stable budgeting: Vegetation management will become an even more critical component of managing transmission and distribution systems. Therefore, an appropriately funded and stabilized budget is crucial to acquire and maintain labor and equipment resources.
  • Proactive engagement: Utilities must achieve or exceed federal, state and local regulatory requirements. If vegetation-caused events go unchecked, utilities will likely face additional agency regulations. Utilities should be proactive to prevent this. For example, utilities should establish strong lines of communication with regulators regarding the impacts of climate change on vegetation management, as well as the importance of potential solutions.

Program Strategies
Climate change increases the likelihood of vegetation-related outages and other environmental risks, such as wildfires. Therefore, UVM professionals must adjust their strategies in managing for initial vegetation clearing and routine maintenance, as well as for catastrophic events that impact the electric utility infrastructure.

Strategies to Consider:

  • ROW widths may be increased for overhead transmission and distribution facilities. Increased widths allow for enlarged vegetation clearances, resulting in fewer vegetation-caused events.
  • Easement or permit language may be revised to improve rights for tree and brush removal, herbicide applications and off-ROW hazard tree mitigation. Utilities must have adequate rights to meet their responsibilities.
  • ROW road access may be improved to allow for more frequent and timely inspections and maintenance. 
  • Transmission and distribution facilities may require construction modifications to help mitigate vegetation issues. For example, utilities may convert an overhead distribution line to underground or relocate the line to a less vegetated area. The establishment of micro-grids may also be an option. 
  • Integrated vegetation management (IVM) may be expanded. For example, some utilities have traditionally focused IVM on transmission systems. Expanding IVM to distribution systems will reap the same benefits by creating sustainable solutions.
  • Inspection and maintenance intervals may be adjusted to ensure compliance with federal and state regulations, and to aid in the identification and mitigation of vegetation/conductor contacts, hazard trees, and brush conditions.
  • Fuel reduction may be initiated on ROWs where past tree clearing activities left debris. Fuel reduction will reduce the impacts of a wildfire and may help protect electric facilities and private property.

The reduction of risk will become more important with climate change. Vegetation management professionals should evaluate how vegetation is creating a risk for a specific facility and how that risk compares to other facilities with vegetation. Then, consider the risk spend efficiency for each specific project. For example, scheduled work activities such as routine maintenance may need to be prioritized based on the reduction of risk, balanced with safety, reliability and cost.

After vegetation-caused ignitions or interruptions, vegetation management professionals should perform a root cause analysis to learn from each event. This data may enable scope of work enhancements, such as species-specific radial and overhang clearances or tree removal strategies. 

Stakeholder communication will become more important in a changing climate.  Science- and data-driven strategies, along with input from stakeholders, will be necessary to achieve program goals and objectives. 

Developing and maintaining relationships with federal, state and local agencies is more important in a changing climate. Utility vegetation management professionals should work cooperatively with agencies to develop solid relationships that lead to mutual understanding and goal setting.

Utility companies should also collaborate with other utilities to share strategies. Membership and participation in organizations like the Utility Arborist Association will encourage collaboration to tackle the impacts of climate change.

Staffing of a skilled vegetation workforce has become an ever-increasing challenge. Appropriate wages and benefits are critical for establishing and maintaining a stable workforce. If utilities want to avoid the worst impacts of a changing climate, their vegetation management program must be well resourced.

Use of Technology for Utility Vegetation Management
Technology is rapidly evolving within the UVM workspace. Technological innovations can reduce safety risks and increase productivity, as they also help manage data to drive decisions. Utility vegetation managers must embrace new technologies to help utilities avoid the worst impacts of climate change.

Light Detection and Ranging (LiDAR) is a technology like radar that can be used to create high-resolution digital elevation models (DEMs) with vertical accuracy as close as 10 cm.

LiDAR has become a commonplace tool for utility vegetation managers. While traditionally a tool for managing transmission utility ROWs, competition and technology improvements are driving down costs. Simultaneously, the use of LiDAR is expanding for utilities. The marketplace for services is now moving into the distribution ROW segment of the industry, including traditional airborne acquisition, as well as ground-based and drone acquisition.

Hyperspectral and Color-Infrared Photography
Two emerging technologies for utility vegetation managers are hyperspectral and infrared photography. Usually coupled with LiDAR, these technologies can be leveraged to aid the identification of dead, dying or diseased vegetation.

Specifically, hyperspectral photography leverages the color spectrum to collect and process information from across the electromagnetic spectrum. Certain objects leave unique “fingerprints” in the electromagnetic spectrum. Since each plant species has its own unique “hyperspectral fingerprint,” this technology enables identification of target species that create management concerns as climate change influences the biodiversity of the utility space.

Color-infrared photography can identify vegetation that is stressed, diseased and/or dying long before the human eye can visually detect a change in plant morphology. The most common use by utility vegetation managers is to identify trees under stress of disease or drought, which can develop into a hazard.

Climate change has caused a complete paradigm shift for utilities. In some states, climate change impacts are already forcing UVM professionals to change everything from how they communicate, to the tools they use, to the very goals and strategies they set for success. Utilities that have yet to face catastrophic extreme weather or vegetation-caused events should proactively prepare now. Should a utility choose not to take these issues seriously now and plan, they could take on the major liabilities of not only new regulations, but also potential legal and criminal liabilities. Planning now could mitigate some or all this liability. Additionally, by embracing and adapting to the new climate reality now, utilities can more reliably deliver safe and cost-effective electricity to their customers in the future.

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