Electricity is often talked about as if it were a simple product—something utilities “make” and customers “use.” In reality, electricity is one of the most complex markets in the modern economy because it cannot be stored at scale easily and must be produced and consumed at the same moment. Understanding how this system works is essential before any meaningful discussion about rising costs, data centers, or regulatory decisions can take place.

At the beginning of the chain is generation . Power is produced by generating units such as nuclear plants, coal plants, natural-gas plants, hydroelectric facilities, wind farms, and solar arrays. Each generator has two key characteristics: how much power it can produce (measured in megawatts, or MW) and how much it costs to operate (measured in dollars per megawatt-hour, or $/MWh). Some plants are designed to run continuously for long periods, while others are designed to start quickly to meet sudden changes in demand.

Once electricity is generated, it enters the grid , a high-voltage transmission network that moves power over long distances. The grid is operated by regional reliability organizations or market operators whose job is to keep the system stable. In some parts of the country, this role is handled by centralized market operators such as PJM Interconnection , which runs competitive power markets. In the Southeast—including Georgia, South Carolina, and North Carolina—the grid falls under the SERC Reliability Corporation , where utilities rely more heavily on long-term planning and bilateral contracts rather than centralized spot markets. Regardless of structure, the physical requirement is the same: supply must exactly match demand at all times, and grid frequency must remain at 60 hertz.

Electricity is bought and sold through several overlapping mechanisms. The first is long-term contracting . Utilities secure much of their power years in advance through power purchase agreements that can last 10, 20, or even 30 years. These contracts provide price stability and ensure that enough generation capacity exists to meet future demand. Nuclear plants, coal plants, and many large renewable projects depend on these long-term arrangements to justify their large upfront investments.

On top of long-term contracts sits the day-ahead market , whether formal or informal. Utilities forecast how much electricity their customers will need for each hour of the next day. Generators then submit offers indicating how much power they can produce and at what price. The system operator selects enough generation to meet the forecasted demand, starting with the lowest-cost resources and working upward. This process establishes an expected operating plan and a preliminary price signal for the next day.

Even with careful forecasting, real life never follows the plan exactly. Weather changes, factories start or stop, and millions of individual decisions affect demand. This is where real-time balancing comes in. Every few minutes—typically every five minutes—the grid operator measures actual demand and adjusts generation up or down. Fast-responding resources such as gas turbines, hydro units, and batteries are dispatched to correct imbalances. Contrary to popular belief, utilities are not shopping for electricity every five minutes; instead, the grid operator is dispatching previously approved resources based on physics and pre-established bids.

A critical concept in this process is economic dispatch . The grid runs the lowest-cost available generators first and only calls on higher-cost units when necessary. The most expensive generator needed to meet demand at any moment is known as the marginal unit , and it sets the market price for that interval. This is why electricity prices can spike during heat waves or cold snaps even if most power is coming from relatively cheap sources.

Separate from energy prices is the concept of capacity . Capacity represents the ability to produce power when it is needed, not just the energy actually delivered. Utilities and grid regions must ensure that enough capacity exists to meet peak demand under extreme conditions. Customers ultimately pay for this through their rates, because maintaining spare generation and transmission capability is essential for reliability, even if those assets run only a few hours a year.

Finally, electricity reaches customers through distribution systems owned by local utilities. Substations step down high-voltage power to usable levels, and distribution lines deliver it to homes and businesses. Regardless of where the electricity was generated or who sold it, the local utility is responsible for safely delivering it to the customer.

In simple terms, the power system works because long-term planning ensures enough resources exist, short-term markets fine-tune supply and demand, and real-time balancing keeps the lights on every second of every day. Prices reflect not just the electricity used, but the cost of building and maintaining a system capable of meeting peak demand reliably. This foundational understanding is critical before examining how large new users—such as data centers—can reshape costs, risks, and regulatory decisions across the Southeast.