Learn how the power grid works and how it is changing.
If Alexander Graham Bell was handed a smartphone, he likely wouldn’t recognize it as a telephone. But if Thomas Edison was shown the U.S. power grid today, he would likely recognise what it was, given how similar it is to the grid he helped build more than a century ago.
The major components of the power grid have changed relatively little in the past century when compared to telephone technology. Here are the basic elements of how electric power is created and delivered:
- Large power plants, burning mostly coal and natural gas, have generated the bulk of America’s electricity. Starting in the 1970s, the U.S. added nuclear power plants that produce carbon-free electricity. Hydropower has also long been a power source, and in recent years solar and wind have become a significant and growing source of energy.
- Transmission lines can be thought of as electricity’s interstate highway system to carry power from where it’s produced to places where it is consumed. When electricity leaves the power plants, substations equipped with step-up transformers increase the voltage of the power that travels across the transmission lines.
- Distribution lines handle the last segment of electricity’s journey to you. High-voltage transmission lines connect to substations that reduce, or step down, the voltage of power to distribution lines like the ones you see in neighborhoods. Those lines connect to meters on homes and buildings that use the power for heating, cooling, lighting and more.
A modern grid emerges
With digital tools and the clean energy revolution, the grid is changing faster than ever before.
- Power plants everywhere. Large power plants still produce the bulk of America’s electricity, but now renewable sources are popping up everywhere: in cities, in oceans, in fields and on buildings – creating a far more decentralized power grid than in decades past. The growth of energy storage and even electric vehicles is allowing excess power from renewables to be saved for when it is needed.
- More efficient transmission. Long-distance transmission lines are a necessary fixture of the grid. Today, high-voltage direct current (HVDC) transmission lines are common in other parts of the world. Compared to the high-voltage alternating current lines used in the U.S., HVDC can move more power more efficiently over long distances and can be buried underground in existing right of ways. As more transmission is needed to carry renewable energy to where it is needed, HVDC lines are being proposed and built in the U.S.
- A smarter distribution grid. Society is increasingly dependent on the power grid yet more powerful and frequent extreme weather threatens grid reliability. With smart sensors and controls, distribution power lines and other grid equipment can form a self-healing smart grid with the capability to restore power quickly and automatically. At the point of connection to homes and businesses, digital smart meters can automatically tell the utility when the power goes out and provide granular energy use information that can be used to help consumers make better energy decisions.
- A two-way relationship is emerging. Power used to flow from big power plants to where it was consumed. Now, buildings and homes equipped with cutting-edge technology can be virtual power plants, reducing demand and sometimes providing power and support for the grid when it is needed. In homes, smart thermostats are a key part of a two-way power grid because they can respond to signals to save energy, and some electric vehicles have capabilities to provide power back to homes or the grid when it is needed. With eligible Nest thermostats, you can sign up for Nest Renew, which can help you take advantage of cleaner or cheaper energy, and Rush Hour Rewards, which helps you earn rewards for saving energy during peak demand periods.