Service Request #4: How Does the Grid in Phoenix Work?

In the summer of 2023, Phoenix experienced its hottest summer on record, with temperatures exceeding 110°F for 31 consecutive days. This extreme heat highlighted the city's total dependence on air conditioning and, consequently, on the electrical grid. Without power, especially during the summer, lives would be at risk. This raises the question of how a city like Phoenix ensures it has enough energy to meet demand, particularly on the hottest days. The electrical grid, often called the largest machine in the world, is a complex and largely invisible system. As cultural anthropologist Gretchen Baky explains, the grid is designed to be "illegible" to the average person. Most people only interact with it through their monthly utility bill, which provides little insight into how electricity is generated or why costs fluctuate. Despite its complexity, the basic components of an electricity system are consistent, regardless of size. Electricity originates from power plants, which traditionally burned coal but have transitioned to natural gas, wind, solar, and hydroelectric sources. The process of generating electricity involves converting heat or kinetic energy into electrical current. For example, in a coal-burning plant, coal dust is combusted to produce steam, which rotates a turbine. Magnets attached to the rotating metal generate an alternating current (AC) as they pass by brushes. This AC involves electrons jiggling back and forth 60 times per second, rather than flowing in a steady stream. This generated electricity then travels through transmission lines, which are the large, high-voltage wires seen spanning long distances. These lines carry enough power to be lethal and are designed for long-distance transport. They eventually lead to substations, which are typically industrial-looking enclosures where the voltage is "stepped down" to a safer level. From substations, electricity enters the distribution network, which carries it closer to homes. Before entering a house, the voltage is stepped down once more by a transformer, often located on a utility pole, ensuring that the electricity delivered to homes is safe for household use. This entire process, from generation to delivery, happens incredibly fast; the electricity that powers a light switch or air conditioner was often generated just a minute beforehand. A crucial aspect of the grid is that, historically, it has had limited storage capacity. Electricity is typically consumed almost immediately after it's produced. This "just-in-time" delivery requires the grid to maintain a perfect balance between the amount of power being generated and the amount being consumed at every second. The system's precise frequency of 60 back-and-forth cycles per second must be maintained. If demand suddenly exceeds supply, this frequency drops, potentially leading to cascading failures and widespread blackouts. The US electrical system is not a single entity but comprises three interconnected grids: the Eastern, Texas, and Western grids. Phoenix is part of the Western grid, which spans from western Canada to Mexico and from the Pacific coast to the Rocky Mountains. This vast network integrates numerous power plants and dozens of utilities, including for-profit companies, municipal entities, and co-ops, across multiple states and even countries. The grid is not just physical infrastructure but also an intricate web of social, political, and economic relationships, with various agreements, state governance, federal regulations, and different business models all working together. The sheer fact that it functions at all is remarkable. Within the Western grid, the Salt River Project (SRP) plays a central role in Phoenix. SRP coordinates power delivery, taking electricity from various sources—such as hydroelectric dams in Oregon, solar farms in Arizona, or natural gas plants—and managing the real-time balance between supply and demand for the Phoenix metropolitan area. Angie Bond Simpson, SRP's Senior Director of Resource Management, is responsible for future infrastructure planning, ensuring Phoenix never runs out of electricity, especially in summer. SRP employs different planning horizons to maintain this balance. Long-term planning, spanning six to 30 years, considers factors like population growth, climate data, and new technologies (e.g., electric vehicles) to inform decisions about building new infrastructure and securing power sources. For day-to-day operations, a "day-ahead" team forecasts electricity needs based on weather predictions and historical consumption data. They then create an energy plan for the next day, "stacking" available power plants—from cheapest to most expensive—to meet reliability and economic goals. Weather-dependent sources like wind and solar are prioritized when available, while dispatchable resources like natural gas, coal, and hydroelectric power act as reliable "faucets" that can be turned on or adjusted as needed. The "real-time" team monitors the actual unfolding of the day, making on-the-fly adjustments. This team includes operators who buy and sell electricity with neighboring utilities to manage surpluses or deficits, and the grid operations team, which focuses solely on system reliability and emergency response. The central control room at SRP, though equipped with numerous screens displaying real-time data, is surprisingly quiet, reflecting the calm and focused environment needed for critical decision-making. Planning for summer is a year-round project. SRP proactively designs the system to meet the projected energy needs of the hottest day, hottest hour, and hottest week of the year, including reserves for contingencies. This proactive approach allows for maintenance during cooler periods. While large-scale blackouts like the one in the Iberian Peninsula are a nightmare scenario SRP aims to prevent through robust planning and inter-utility relationships, more common outages are caused by mundane events like car accidents hitting power poles, gender reveal party confetti, or Mylar balloons interfering with distribution lines. Heat waves pose a particular challenge because every piece of infrastructure has a temperature rating. The power grid, like airport tarmacs, is not designed to run "full tilt" at extreme temperatures without cooling off. Components like transformers and those made of rubber or plastic degrade faster in intense heat. While Phoenix has avoided widespread rolling blackouts, the summer of 2023, with its record-breaking heat, created immense stress for operators. The system performed well, but the consecutive days of extreme heat meant the margin for error was minimal, requiring constant vigilance, double-checking, and communication across the region. The challenges for the grid are growing. Phoenix is one of the fastest-growing cities in the US, and major industrial customers like data centers are increasing demand. This rapid growth creates a significant lag in infrastructure development, as siting and constructing new transmission lines or generators can take years, even decades. The system, built and adapted over a century, faces its biggest challenge yet: hotter summers and surging demand. The grid, often taken for granted when it works, becomes critically important when it falters, underscoring the constant efforts of thousands of dedicated professionals at SRP to keep the power flowing.