The United States is the second-largest energy consumer in the world after China. 2019 estimates put U.S. power usage at 100.2 quadrillion Btu. annually. This is approximately one-fifth of the world’s total energy output. Severe weather is the primary cause of power outages in the country, costing the economy $18 billion — $33 billion every year.
- The U.S. national power grid comprises three independent grids — the Eastern Interconnection, the Western Interconnection, and the Electric Reliability Council of Texas (ERCOT) Interconnection. The transmissions occur at high voltages ranging from 230kV, 345kV, 500kV, and 765kV. The primary function of the national power grid is to deliver power produced by power-generating companies. The U.S. Department of Energy refers to the national grid as “an interstate highway system for wholesale electricity commerce.”
- Except for individual power grids in the states of Hawaii and Alaska, the national power grid also offers interconnectivity between separate power utilities.
- Forty-eight percent of United States electricity is coal-generated. Natural-gas-powered power plants account for 21.5%, nuclear plants 19.4%, hydroelectric power plants 6%, and petroleum-driven plants 1.6%.
- The remainder is generated via renewable energy sources, mostly biomass (43%), geothermal (2%), wind (24%), and solar (9%). This segment (renewable energy) is the fastest-growing source of electricity in recent years.
- Aside, the power generating sector emits 40% of the country’s total GHG emissions. This is roughly 10% of the global emissions.
- In general, the national power grid constitutes “over 7,300 power plants, 160,000 miles of high-voltage power lines, and millions of miles of low-voltage power lines and distribution transformers supplying power to over 145 million customers.”
- The U.S. electricity market comprises both retail and wholesale components. Wholesale markets refer to the sale of electricity and electric utilities among traders before it is sold to consumers.
- Retail electricity market refers to the sale of electricity to the eventual consumer. Nonetheless, both markets can be competitively or traditionally regulated.
- When the wholesale electricity market is traditionally regulated, it essentially means that vertically-integrated utilities produce and distribute electricity to consumers. These utilities own the generative, transmission, and distributive systems in the whole power matrix.
- The restructured competitive wholesale market is managed by independent system operators (ISOs). These players employ competitive market mechanisms to allow non-utility generators and independent power producers to sell electricity.
- In restructured competitive markets, the ISOs are unlikely to own the power-generating and transmission resources even though they sell electricity to consumers.
Operation during regional failure
- The Energy Information Administration (EIA) developed an interactive map to monitor energy supplies across the U.S. in real-time. On an hourly basis, the system compares energy production and consumption and predicts regions that might experience power fluctuations due to overconsumption, underproduction, or power failure.
- On the interactive map, areas generating surplus electricity appear orange. Regions where power production is not at par with projected consumption, are coded blue. By clicking on these areas on the map, the officials can see how much power is needed to keep the affected region’s power supply stable.
- This is possible due to the interconnectivity of the national grid. Effectively, this means surplus power from over-supplied areas can be diverted to shortage areas.
- The diversions happen automatically because, as EIA explains, “power disturbances happen very fast to depend on human intervention to detect losses and manually bring on new generating capacity.”
Case studies of the national grid aiding regions affected by power disruptions
- In 2011, an earthquake hit the Washington DC area, causing the safety systems at two nuclear power stations in Virginia to go off. This reduced the power supply to the DC area for 12 minutes. Generating systems in the area detected the fall-off and automatically upped their production to absorb the missing output and stabilize the system.
- In August 2011, a heatwave drove temperatures as high as 100 Fahrenheit in Texas, and as a result, people turned on air conditioning simultaneously. This created a power surge, placed a strain on power stations, and forced them to operate beyond their standard capacities. However, the national grid diverted power from regions with surplus power to relieve the strain on the power stations.
- The worst power outage in U.S. history equally underscores how the national grid protects regions from dangerous oversupply. In 1965 a massive power blackout hit eight states leaving more than 30 million people without power. It lasted 13 hours.
- Even though the cause was attributed to human error, further analysis indicates a protective relay on a transmission line near Niagara transmission station tripped a circuit breaker when it noticed irregular power flow.
- In reality, a sudden drop in temperature caused consumers to use more power to heat their homes, thus straining the system. This chain reaction resulted in a power surge in Lewiston, New York. Since the relay was set too low, it deactivated a major power line supplying power to Northern Ontario. Power flowing on this line was, similarly, diverted to other lines creating overloads in these lines and making their protective relays go off. All this took place within five minutes.