Why is hydropower important when other power sources go dark?

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

Understanding the power grid and how renewable sources fit in

The power grid is evolving to include ever-higher levels of solar and wind, which don't provide inertia. Should system planners and operators panic?

More batteries in the power grid would create an on-demand energy reservoir

Most power grids are inefficient because they require enough generation capacity at all times to avoid blackouts. This means at any given time, as much as 50% of generating capacity at power plants can go unused. Batteries would reduce this inefficiency and allow for real-time adjustments.

An overview of hydropower

Hydropower, or the use of the natural flow of moving water to generate electricity, is one of the oldest and largest sources of renewable energy.

A look at how power is restored after an outage on the electric grid

From minor system failures to more widespread blackouts, crews begin by assessing damage done to infrastructure, such as transmission towers and distribution power lines. Prioritizing essential services, such as hospitals, crews then begin restoration, starting with any damage found closest to the power generation and working down the distribution system to customers.

How microgrids can modernize electric grids to meet 21st-century demands

Just as having a single, outdated internet service provider leaves an area helpless in the case of an outage, failures in the electric grid can be devastating to communities. For this reason, hospitals, data centers, and other structures have their own backup power supplies. However, decentralized microgrids would provide areas with their own electricity generation and storage, thereby reducing overall grid load and reliance while enabling better electricity management.

Learn how critical services, infrastructure, and people would be impacted by a US-scale blackout—a nationwide, long-term failure of the electric grid.

Examining the causes of power outages, from system damage to preventative measures

Stray balloons, contact with trees, malfunctioning equipment, and severe weather are among the causes of failures that can cause widespread, unplanned blackouts. Although contingency options that rely on alternative transmission pathways to deliver electricity from generators to consumers may be possible, some shutoffs, brownouts—available power is reduced—and cycles of repeated outages may be intentionally implemented to protect public safety.

Geothermal power plants can provide large-scale energy storage for other systems

These facilities can store excess energy from solar and wind power as hot water or steam, which can be used to run turbines to generate electricity when other renewable energy sources are unavailable. Simulations have found efficiencies of 90% during a storage-use cycle, making it comparable to lithium-ion batteries.

The engineering underlying the electric grid and why it needs to be modernized

The system includes generators for producing electricity and millions of miles of transmission and distribution lines to transport the energy. The substantial increase in the number of electronic devices and electrical demand since the construction of much of the grid in the mid-1900s has strained infrastructure, requiring continuous upgrades and massive investments in new construction.

Larger shares of solar power generation produce larger energy demand curves

Because solar energy is only available during daylight hours, transitioning an electric grid to solar requires significant ramp-ups and ramp-downs of other energy sources during mornings and evenings to compensate. Widespread adoption of affordable energy storage solutions can soften these curves.

The benefits and risks of smart grids, from improved efficiency to cybersecurity risks

By using a network of devices, including digital meters, sensors, and controllers, smart grids can quickly detect mechanical issues and fluctuations in supply and demand, automatically adjusting electricity flow to prevent cascading failures. While this is important for variable solar and wind power generation, many of these computer systems are designed to be controlled remotely, which increases the risk of malicious access.

Simulate the effects of changing supply and demand on the electric grid

In this application, users can modify the demand of fictional cities and the supply of various generators, including a nuclear power plant and a wind farm, which can be disconnected from the grid. Notice that current may flow into or out of external systems to compensate for available generation. See what it takes to cause a blackout in different cities or shut down the entire grid.

Solar energy alone can fully power the world if transmission hurdles can be resolved

When light strikes a photovoltaic cell, electrons are loosened, which travel through a circuit where the energy can be used. Distributing energy from high solar intensity regions and storing energy for non-daylight hours is logistically challenging and costly.

Electrical grids worldwide must double their power delivery capacity by 2050 to meet surging demand from AI and electric vehicles.

Electric grids that rely on solar power must compensate for reduced electricity generation during solar eclipses.

Niagara Falls is New York State’s biggest electricity producer

The Robert Moses Niagara Power Plant and Lewiston Pump-Generating Plant together produce up to 2.6 million kilowatts—providing about 20% of New York State’s hydropower and supplying electricity to over 3 million homes.

View breakdowns of the world's and each nation's electricity comes from

These charts show how the shares of generated electricity sources—solar, wind, hydro, nuclear, bioenergy, oil, gas, and coal—have changed since 1985. Since 2010, an increase in renewable sources has offset the share lost by nuclear and fossil fuels.

View a breakdown of global electricity generation in 2025, led by coal power plants.

Learn why electrical substations are needed to provide safe electricity with minimal energy loss

These typically fenced-off facilities with steel boxes or cylinders topped with cone-like caps house circuit breakers, fuses, and switches that can isolate sections of the grid to prevent electrical failures from spreading. Substations use transformers to modify electrical voltage and are customized to the generation, transmission, and distribution networks they interconnect.

All clean energy technologies rely heavily on critical minerals

Although many of these minerals have been used for decades, such as copper in electrical wiring, the accelerating demand for them has strained existing extraction and processing systems. Supply chain disruptions for these materials may delay and increase the cost of transitioning to solar, wind, hydroelectric, and geothermal power.

During emergencies, backup diesel generators in data centers emit substantial pollution

During power outages or when the power grid is at insufficient capacity, these generators emit 200 to 600 times more nitrogen oxides—a greenhouse gas—than natural gas plants, as well as fine particulate matter linked to respiratory disease.

Rain-catching tubes provide new hydropower source for tropical regions

An experiment in Singapore showed that charge separation could be established by rainwater flowing through narrow tubes. The separation, which creates a voltage, could be scaled up in regions of high rainfall to provide a clean energy source.

Niagara Falls helped decide the battle between AC and DC power

In the 1890s, Niagara Falls became the proving ground for alternating current (AC) when Tesla and Westinghouse built the first large-scale AC hydroelectric plant—defeating Edison’s push for direct current (DC) in the US electrical system.

Renewable energy basics

Discover the many benefits to using renewable energy resources, but what is it exactly? From solar to wind, it’s the fastest-growing source of energy in the world – and how we can use it to combat climate change.

Establishing the wind power grid required incentives, reliability, and affordability

Although wind was harnessed to generate electricity for individual buildings in the late 1800s, high costs, mechanical issues with turbines, and better fossil-fuel alternatives delayed wind power's widespread growth. After the oil crises of the 1970s, governments sought alternative energy sources and, in the decades that followed, provided tax credits to expand the wind power market.

As of 2025, wave power projects remain in early research and testing phases

Waves can become a steady source of renewable energy because they do not pause like wind and solar power do. However, funding gaps and the effects of storms, salt exposure, and biofouling—mussels and other sea creatures attaching to wave machines—have presented challenges in scaling the technology beyond testing sites.

Discover why Texas runs its own electric grid, separate from the other US interconnections

In 1935, electrical utilities in the Lone Star State opted to rely on the state's own fossil fuel reserves to power an independent electric grid. While this prevented the federal oversight required for the Eastern and Western Interconnections that span multiple states, it also meant Texas's grid was unable to draw sufficient backup power during the winter 2021 power grid failure.

Why decarbonizing the entire electric grid is impossible with its current infrastructure

Fossil fuel plants can be built anywhere and have thus typically been built near highly populated areas, such as coastal cities, where electricity demand is high. However, certain renewable resources operate most efficiently in specific regions, such as wind turbines in the Midwest, and therefore require substantial transmission infrastructure to be constructed to transport the generated electricity.

Understanding how non-profit entities manage electric grids to ensure supply-demand balance

Independent System Operators in smaller areas and Regional Transmission Organizations that operate across multiple states run wholesale electricity markets. Electricity suppliers can submit competitive bids to meet estimated demand in day-ahead markets while keeping consumer costs low. ISOs and RCOs also inform markets of deviations in these estimates so that suppliers can adjust how much power they generate, which is then bought and sold in real time.

View a map of the balancing authorities managing electric systems and costs throughout the continental US

These are made up of utilities, Power Marketing Administrations—hydropower marketers from the Department of Energy—and groups of utilities that have formed regional entities called Regional Transmission Organizations or Independent System Operators. Collectively, balancing authorities ensure supply meets demand and can direct utilities to implement rolling blackouts to prevent permanent damage to electrical equipment.

View a dashboard of hourly electricity demand and generation across the continental US.

Tesla's alternating current power's most of the world's electric grids

In 1879, Thomas Edison’s light bulb relied on direct current, but such currents can't efficiently transmit power over long distances. Nikola Tesla introduced alternating current, which feature far fewer energy loses. Despite Edison’s attempts to discredit AC, Tesla proved its efficiency by lighting the 1893 Chicago World’s Fair.

The unpredictability and brevity of lightning make lightning power impractical

While a typical lightning strike provides 30,000 amps at 300 million volts, the bolt only lasts about 30 microseconds. If the electrical surge could be captured—assuming one knew beforehand where it would strike—it would only provide enough electricity to power one home for about 6.4 hours.

The history of the North American power grid, which is composed of five major grids

Thomas Edison's Pearl Street Station was the first US commercial power plant, burning coal to power lamps for some Manhattan residents. Over time, local power plants would be bought out by larger ones, forming interconnected systems spanning multiple states. Today, the Eastern Interconnection and Western Interconnection are the largest of these systems.

Find out how much energy in the US comes from renewable sources and other FAQs

Browse frequently asked questions about renewables, from the amount of energy production by state to the cost of electricity generation by power source.

Among renewable sources, geothermal rivals hydropower in lifetime cost

As of 2024, the levelized cost of energy—the average cost per unit of energy over the lifetime of a power plant—for geothermal power is surpassed only by solar photovoltaic and onshore wind. Geothermal's LCOE has remained relatively unchanged since 2007, with significant decreases held back by significant upfront installation costs.

Wind turbines explained

Wind turbines have powered homes since 1887, and today they’re stronger, quieter, and more reliable than ever. Offshore wind could power millions and grow fast enough to meet climate goals.

Niagara power helped electrify early New York City

Tesla's AC system at Niagara Falls was so successful that electricity generated there lit up Broadway theaters and powered NYC's subway system in the early 1900s.

Despite electric usage concerns, EV charging accounts for less than 1% of grid load

Other popular myths about EVs include battery failure concerns—failure rates are less than 1% on newer models—and that there are no places to charge cars, though both at-home outlets and more than 77,000 stations on the road are available.

The world's first AC hydroelectric power plant incorporated Tesla's engineering

Built at Niagara Falls, New York, the plant alternating current electricity was hailed as the future of power generation. Tesla's fascination with Niagara Falls is traced to his seeing a photo of the waterfalls when he was still a child.

Solar power is converting the sun's energy into thermal or electrical energy

Solar energy is the most abundant renewable energy resource. It can be captured in photovoltaic cells to generate electricity, solar heating and cooling technologies for temperature control, and concentrated solar power to drive steam turbines.

Niagara's flow is changed artificially to accommodate tourists and power generation

The natural wonder is also the site of great engineering feats, from the Welland Dam that first allowed ships to travel from the upper lakes to the St. Lawrence Seaway, to one of the first hydroelectric dams.

Lessons from the 1973 energy crisis still echo in today’s geopolitical battles over oil

The video from the Economist highlights how energy supply disruptions can be weaponized—just as in 1973, today’s gas cutoffs (Russia throttling supplies to Europe after their invasion of Ukraine) reveal the ongoing importance of strategic energy resilience.

As of 2022, just 0.5% of installed renewable energy capacity worldwide is geothermal

Despite being able to generate electricity regardless of the weather, solar (28%) and wind (27%) are far more prevalent, primarily because of their lower upfront costs. Geothermal plants use 88% less space than solar farms to produce the same energy, but have been restricted to geologically active regions.

As much as 10% of home electricity use comes from unused devices left plugged in.

AI's growing energy demands are driving tech companies to consider nuclear power

Big Tech has rebranded nuclear power as a green solution to address the strain on the grid from millions of people using power-hungry AI tools. As of mid-2025, generating one image uses as much electricity as charging the average smartphone, or leaving a household light bulb on for 87 consecutive days.

Explore global solar resources with this interactive map

One of the biggest challenges to deploying solar panels is whether electricity can be generated reliably when needed, day after day. This detailed interactive map calculates the solar power output potential of regions worldwide and provides a visual comparison between locations such as North Africa and the US Midwest.

Nuclear power supplies almost half of US carbon-free energy

As of 2023, nearly 20% of US electricity comes from nuclear power, but most reactors were built from 1971 to 1990. Expansion slowed due to safety concerns, high costs, and competition from natural gas.

Fracking technology can help make geothermal power possible almost everywhere

Generating electricity from Earth's thermal energy has previously required existing underground reservoirs of hot water and permeable rocks through which the fluid naturally escapes. Today, fractures can be artificially created to form fluid pathways, and surface water can be injected underground and brought back to the surface.