This grid moves energy, but not always reliably | Science News for Students

This grid moves energy, but not always reliably

Engineers are working to make the distribution of electricity more reliable and resilient
Jan 24, 2019 — 6:45 am EST
a starry night sky over power pylons and high-voltage power lines

A failure of the electric system can quickly leave millions of people in the dark.


More than three million people in Puerto Rico lost electricity in September 2017. Back-to-back hurricanes had just slammed into the island. Floods from Maria, the more powerful of them, knocked out many power plants. Winds and mudslides toppled towers and the power lines they carried. Explains climate scientist Juan Declet-Barreto: “Losing power is not merely inconvenient. In a climate-ravaged, tropical area like Puerto Rico, it’s life-threatening.”

With no electricity, hospitals had to delay surgeries. They couldn’t run many scans or tests, either. Without timely care, some patients died. Puerto Rico’s water-treatment plants lost power during Maria. As a result, people across the island lost access to clean water. And few people could cook or refrigerate food. Anyone lucky to have a portable stove or generator had to stand in long lines for fuel. Meanwhile, schools and businesses closed or cut their hours.

Declet-Barreto works for the Union of Concerned Scientists in Washington, D.C. But he grew up in Puerto Rico. His parents and sister’s family still live there. Phones went out shortly after Hurricane Maria made landfall. For days, Declet-Barreto didn’t know his family’s fate. Fortunately, they fared pretty well. And their electricity came back within a few weeks.

a photo showing power lines downed by fallen trees
Even before Hurricane Maria hit in September 2017, Hurricane Irma had downed trees, harming much of Puerto Rico’s island-wide electric grid.
Kenneth Wilsey/FEMA

Many others were not as lucky. Four months after Maria, about one-third of the island still lacked electricity. Even after six months, roughly one in 10 people still couldn’t switch on the lights. It was nearly a year after Maria hit before everyone again had power.

Hurricanes are severe events, but Maria was especially bad. Its winds and flooding “couldn’t have been a more literal ‘perfect storm’ of conditions,” Declet-Barreto says. Its winds and fallen trees destroyed much of the island’s system for carrying electricity from power plants. Even before Maria, the company that delivers electricity had not been replacing aging equipment.

Puerto Rico is far from the only place that has struggled to keep its lights on, phones charged and computers powered up.

The electric grid is a term for the system that brings electricity from where it’s made to homes and businesses. Nearly everyone depends on that system. Yet as important as it is, this grid faces a host of threats. Some are simple and old. Others are complex and very new.

Fortunately, engineers are working on them. Their research aims to keep the grid going, despite natural — and some decidedly unnatural — disasters. Other projects are looking at how to get the lights back on more quickly after power outages. Still more work looks for ways to rely less on fossil fuels (mainly coal, oil and natural gas) and instead generate more electricity using cleaner wind and solar energy. The cleaner sources might not only help slow global warming, but also make the grid more resilient to shutdowns.

Bad weather, naughty squirrels and more

The grid has many thousands of pieces and parts. Power lines can stretch across continents. The grid's electricity flows along many paths. Both its supply of energy and the public’s need for it can vary with the weather, time of day or day of the week.

Power engineers find it a challenge to keep such a complex system running smoothly. “We need to keep things perfectly balanced” says electrical engineer Chris Pilong. In other words, the electricity coming onto the grid at any time must match the amount being used. Pilong works at PJM Interconnection in Audubon, Penn. That company runs the grid for all or parts of 13 states plus Washington, D.C.

It doesn’t take much to throw the system out of whack. Too many people using too many air conditioners, computers, ovens and other appliances at the same time can disrupt the grid. Winds, falling trees and a build-up of ice can all bring down power lines. In fact, bad weather and other routine problems cause most U.S. power outages, a May 2018 report finds. It was authored by Grid Strategies. That’s an energy-analysis group based in Washington, D.C.

a photo of a power grid control room
Running the grid takes lots of people, computers and equipment. Here’s part of the control room at PJM, which operates the grid for all or parts of 13 states and the District of Columbia.
Courtesy of PJM

PJM and other grid operators know problems can and will arise. That’s why they often have power plants on standby. Those plants can power up if another plant goes down. However, catastrophic storms can overwhelm most backup plans, says Declet-Barreto. And climate change could worsen such events and make them more frequent.

The sun can set off a different type of “weather” problem. Though rare, it can be severe. One 1989 power blackout in Quebec and the northeastern United States, for instance, was triggered by a coronal mass ejection. That’s a powerful burst of gas and magnetic energy from the sun. This stellar storm hurled electrically charged matter into space that messed with Earth’s magnetic field. This sent rogue electrical currents through parts of the grid.

Georgios Karagiannis is an environmental engineer who manages disaster risks. He works at the European Commission’s Joint Research Centre in Ispra, Italy. Rogue currents from space aren’t an energy bonus for Earth-bound electricity users, he notes.

Far from image of a coronal mass ejection from the sun

An image of the United States at night from orbit with areas of high population showing as bright clusters of light. There are fifteen black circles outlined in white representing the 15 largest U.S. metro areas.

a squirrel sitting on a powerline

a photo of a power pole downed by an ice stormThose strong solar-flung electrical surges flow in one direction only, he explains. Yet the grid tends to transport current that changes direction many times per second. If space weather’s one-way surge of direct current enters that two-way alternating current grid, it can cause power outages. It also might harm costly equipment.

Then there are threats posed by terrorism. Bombs could destroy large power plants or transmission centers. Scarier still would be an electromagnetic pulse (EMP). It’s a huge burst of energy released by a nuclear blast high above Earth’s surface. If triggered in the right place, an EMP could knock out electricity across the United States and parts of Canada — perhaps for weeks or more. A 2017 report by the Electric Power Research Institute, based in Palo Alto, Calif., warned of EMP risks to the U.S. power grid.

Then there’s cybercrime. Sensors, meters and other grid equipment "talk” with each other through computers. On July 23, 2018, the U.S. Department of Homeland Security warned grid managers that Russian hackers had gotten into the computer systems that run many American energy companies. They reported that such hackers could act as terrorists and remotely disrupt or turn off part of the nation’s supply of electricity.

Yet another bad actor has been tormenting grid operators: the backyard squirrel! This fluffy-tailed beast chews through wires. In 2016, squirrels caused almost 3,500 outages in the United States. Nearly 194,000 customers lost power from squirrel damage that year, notes the American Public Power Association.

a close up photo of a coating applied to wires showing water droplets beading up and rolling off
Tiny nanostructures in special coatings make water bead up and roll off. Engineers designed the new coatings to keep ice and salt water from building up on wires and other equipment in the electric grid.
Courtesy of the Electric Power Research Institute

Andrew Phillips is an electrical engineer. He works for the Electric Power Research Institute, or EPRI, in Charlotte, N.C. His group’s mission: Toughen the electric grid “to put up with events that come and hit us.”

For one project, Phillips’ team is developing a special porcelain coating for electric wires. Teeny structures in the ceramic material won’t let moisture stick. Water or ice “rolls off in a ball,” Phillips notes. In freezing weather, this should prevent an ice build-up that could bring power lines down.

EPRI also is working on coatings to keep salt and other chemicals from harming insulators. These are materials that jacket power lines or equipment. They prevent a range of problems. (These include short circuits — accidental diversions of an electric current). If field tests go well, electric companies could start using some of these new coatings within a year or two.

Phillips and his team also work on robots, advanced sensors and remote-controlled drones. Such tools can pinpoint problems such as downed wires or too much heat along wires and in other grid equipment. Teams might then rush in for repairs before a fire breaks out, equipment shuts down or other problems take place.  

Looking at the big picture

Protecting elements of the grid is good. But sometimes that may not be good enough. The grid contains thousands of parts. So a piecemeal fix for failing parts may not always be the best way to go, says Karagiannis at the European Commission’s Joint Research Centre.

For example, floods can trigger explosions at electrical substations. (These centers control the voltage of the electric current. They make it possible for cities and neighborhoods to use the electricity that power plants generate.) One way to prevent flood damage is to build substations on higher ground. Another is to put walls around them to keep flood waters at bay.

But those actions deal with just one bit of the grid and only one threat, Karagiannis notes. His preference: Make sure each local area in the grid can get power from at least two sources. Then if a flood hits one substation, some other source could still supply power. So-called “smart grid” technologies could use sensors and computers to do the re-routing. He and his colleagues described this in a December 2017 report from the Joint Research Centre. Electric companies still would need to deal with flooding or other disasters, but many fewer people might lose electricity.

a photo of cows grazing in a pasture with wind turbines in the background
Many farmers now lease land to wind-power generating facilities. It brings extra income to rural areas.

Using more clean-energy sources, such as wind and solar power, also should help strengthen the grid, Karagiannis and Declet-Barreto argue. Those and other renewable resources generated almost one-sixth of U.S. electricity in 2017, notes the Energy Information Administration in Washington, D.C.

Most electricity is generated by burning fossil fuels. That burning has been polluting the air and contributing to global warming. Cleaner forms of energy could curb those emissions. And here’s another potential payback from such a change: Slowing global warming should cut the growing number of extreme storms and heat waves that themselves stress the grid.

a photo of workers installing solar panels in Puerto Rico
A crew works to install solar panels at Caguas, Puerto Rico. Equipment provided by Water Mission will help run a pump for the community’s water supply.
Yuisa Rios/FEMA

Wind turbines and solar power also can be spread throughout a region. This is known as distributed generation. If a large power plant goes down or a storm crops up at one spot, unaffected generators could still provide power.

Puerto Rico’s grid relies heavily on a few large power plants. A problem at any one of these — or at some link between them — could cause a widespread power outage. And that’s what happened when hurricane Maria struck. A similar problem happened early in 2018. That’s when a bulldozer brought down a line between two power plants on Puerto Rico’s south coast. An island-wide power blackout followed.

In a June 2018 report on Puerto Rico’s electric grid, the U.S. Department of Energy advised the island to produce more of its electricity from renewable sources and distributed generation.

Microgrids and batteries

As strange as it might sound, one way to make the electric grid stronger is to break it up into tiny pieces. But not all the time — just when there’s a problem. A microgrid can add protection. These are systems that can make and distribute electricity to a small area. It’s a type of distributed power generation.

Under normal conditions, a microgrid connects to the full grid. But in an emergency, it can break that link and power some small region on its own. New York University became one such microgrid when Hurricane Sandy hit New York City in 2012. While most of the borough of Manhattan lost power, the school’s lights stayed on.

NYU could do this because it burns natural gas to heat water and its buildings. Some of the heat produced normally ends up as waste. The university uses that excess heat to run a turbine. It powers a generator that makes electricity. This bonus power even runs air conditioners for cooling.

a photo of a wall of power bank equipment
New York University’s combined heat-and-power plant uses “waste” heat to make electricity. Banks of equipment like this direct the electricity to where it’s needed or to help feed the grid in New York City. In an emergency, the system can disconnect and run independently as a microgrid.
K. Kowalski

Case Western Reserve University in Cleveland, Ohio, hosts a far smaller microgrid. This “living laboratory” lets researchers try out ways to improve the grid, explains Alexis Abramson. She co-directs the school’s Great Lakes Energy Institute. Some projects at her lab are probing better ways to store energy from renewable sources. It’s an important goal.

Based on sunlight, weather and the time of day, solar energy and wind power produce varying amounts of electricity. People also tend to use more electricity at certain times most days, such as middle- to late afternoons.

Power companies pay more (and may charge more) for energy at times of greatest need — those periods of peak use. Homeowners or companies that own solar panels or a wind turbine would rather feed their energy into the grid during these peak times to earn more money. But much of their power may have been generated at non-peak times. Storing that power for sale later at peak periods takes good batteries.

“Batteries are really where we’re going to see the future evolve,” says Abramson. More battery power would let renewable energy replace more fossil-fuel power plants. Batteries can make renewable energy work like “always-on” power. Batteries also can become a back-up if the larger grid goes down. They can allow customers to temporarily break away from the grid and use the energy they’ve stored.

Toward that end, several projects at Case Western Reserve focus on what are known as flow batteries. Instead of a fixed-size battery, they store different liquids in separate tanks. When these liquid chemicals are allowed to mix, they react to produce electricity. In theory, the chemical tanks could be any size. And they should last longer than normal batteries. So flow batteries could supply a big building, a microgrid — or perhaps even a larger part of the grid.

Electric cars will be part of the grid’s future too, notes Laura Cozzi. She’s an economist and environmental engineer in Paris, France. There, she works for the International Energy Agency. Batteries power these vehicles. People often charge them up at off-peak times, when the electricity costs less. If enough people get electric vehicles, many of those batteries could work together with the grid.

For example, plug-in stations at homes or workplaces could let people’s vehicles store excess renewable energy. And those vehicles might then discharge a bit of their electricity to balance the grid at times of high demand. Then they would charge up again in time for drivers to go places. That’s the word from researchers at the Lawrence Berkeley National Laboratory in California. The team’s study appeared May 16, 2018 in Environmental Research Letters.

What can you do?

You don’t control the grid, but you do use it. You can reduce demands on the grid — and save money — by using electricity more efficiently. Here’s how:

  1. Urge your family to use a “smart” thermostat. Such a computer-controlled device lets you adjust energy use for different times of day (such as when you might be asleep or away from home). Some of these thermostats even let you make changes from a phone’s app when you’re away from home.
  1. Set the thermostat a bit warmer in summer and cooler in the winter. Open windows to let cool night air in during the summer. And close curtains to keep out heat on hot days.
  1. Replace burned-out lights with long-lived LED bulbs. LEDs cost more to buy but save electricity — and money — during use.
  1. When your home needs new appliances or electronics, encourage your family to shop for energy-saving models.

Urge friends and family to save electricity too. And tell your lawmakers what you want to see for energy policy. After all, the electricity that comes through wires to your home is just one form of power. You also have power — the power to make your voice heard.

Power Words

(more about Power Words)

alternating current     (in electricity) Often abbreviated AC, alternating current is a flow of electrons that reverses direction at regular intervals many times a second. Most household appliances run off of AC power. But many portable devices, like music players and flashlights, run off of the direct current (DC) power provided by batteries.

app     Short for application, or a computer program designed for a specific task.

battery     A device that can convert chemical energy into electrical energy.

blackout    (in energy) The loss of electric power to a broad area, and so named because all of the electric lights in the affected area will blink off when this occurs (unless they have a backup electric generator).

borough     (in New York City) One of five parts of the city: Brooklyn, the Bronx, Manhattan, Queens and Staten Island. Each has a limited degree of self-government, and the borders of all but the Bronx were originally designated by the English in 1683 as separate New York counties.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

circuit     A network that transmits electrical signals. In the body, nerve cells create circuits that relay electrical signals to the brain. In electronics, wires typically route those signals to activate some mechanical, computational or other function.

climate change     Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.

colleague     Someone who works with another; a co-worker or team member.

continent     (in geology) The huge land masses that sit upon tectonic plates. In modern times, there are six established geologic continents: North America, South America, Eurasia, Africa, Australia and Antarctica. In 2017, scientists also made the case for yet another: Zealandia.

current     (in electricity) The flow of electricity or the amount of charge moving through some material over a particular period of time.

direct current     (in electricity) Often abbreviated DC, direct current is a one-way flow of electrons. DC power is generated by devices such as batteries, capacitors and solar cells. When a circuit needs DC power, certain electronic devices can convert alternating current (AC) power into a direct current.

disrupt     (n. disruption) To break apart something; interrupt the normal operation of something; or to throw the normal organization (or order) of something into disorder.

distributed generation     (in energy) The generation of electric power by small systems dispersed over a broad area. Rooftop solar panels are one example.

drone     A remote-controlled, pilotless aircraft or missile.

eject     (n. ejection) To suddenly move or force something out of its container or current position.

electrical engineer     An engineer who designs, builds or analyzes electrical equipment.

electric current     A flow of electric charge — electricity — usually from the movement of negatively charged particles, called electrons.

electricity     A flow of charge, usually from the movement of negatively charged particles, called electrons.

electromagnetic     An adjective referring to light radiation, to magnetism or to both.

electronics     Devices that are powered by electricity but whose properties are controlled by the semiconductors or other circuitry that channel or gate the movement of electric charges.

engineer     A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.

environmental engineer     A person who uses science to study and solve problems in ecosystems — from forests to the human body.

evolve     Nonliving things may also be described as evolving if they change over time. For instance, the miniaturization of computers is sometimes described as these devices evolving to smaller, more complex devices.

fossil fuels     Any fuels — such as coal, petroleum (crude oil) or natural gas — that have developed within the Earth over millions of years from the decayed remains of bacteria, plants or animals

generation     A group of individuals (in any species) born at about the same time or that are regarded as a single group. Your parents belong to one generation of your family, for example, and your grandparents to another. Similarly, you and everyone within a few years of your age across the planet are referred to as belonging to a particular generation of humans. The term also is sometimes extended to year classes of other animals or to types of inanimate objects (such as electronics or automobiles).

generator     A device used to convert mechanical energy into electrical energy.

global warming     The gradual increase in the overall temperature of Earth’s atmosphere due to the greenhouse effect. This effect is caused by increased levels of carbon dioxide, chlorofluorocarbons and other gases in the air, many of them released by human activity.

grid      (in electricity) The interconnected system of electricity lines that transport electrical power over long distances. In North America, this grid connects electrical generating stations and local communities throughout most of the continent.

hack     (in computing) To get unapproved — often illegal — access to a computer, usually to steal or alter data or files. Someone who does this is known as a hacker.

hurricane     A tropical cyclone that occurs in the Atlantic Ocean and has winds of 119 kilometers (74 miles) per hour or greater. When such a storm occurs in the Pacific Ocean, people refer to it as a typhoon.

Hurricane Maria     The 8th Atlantic hurricane of the 2017 season that barreled through the Caribbean, devastating several islands — especially Puerto Rico. It reached 75 mile-per-hour maximum sustained winds at 5 p.m. on September 17th. Within one 18-hour period, it strengthened rapidly from a category 1 to an extremely dangerous category 5 hurricane. It made landfall in Puerto Rico with as a strong category 4 storm and maximum sustained winds of 155 mph.

insulator     A substance or device that does not readily conduct electricity.

LED     (short for light emitting diode) Electronic components that, as their name suggests, emit light when electricity flows through them. LEDs are very energy-efficient and often can be very bright. They have lately been replacing conventional lights for home and commercial lamps.

link     A connection between two people or things.

magnetic field     An area of influence created by certain materials, called magnets, or by the movement of electric charges.

matter     Something that occupies space and has mass. Anything on Earth with matter will have a property described as "weight."

microgrid     (in energy) One or more relatively small generating stations that feed electricity into the power lines that make up a large electric “grid.” During emergencies, the microgrid can sever itself from the larger grid to feed power into a small region, preventing a local blackout.

natural gas     A mix of gases that developed underground over millions of years (often in association with crude oil). Most natural gas starts out as 50 to 90 percent methane, along with small amounts of heavier hydrocarbons, such as propane and butane.

outage     (in energy) A term for a region that temporarily loses power (usually electric power) or the ability to operate.

policy     A plan, stated guidelines or agreed-upon rules of action to apply in certain specific circumstances. For instance, a school could have a policy on when to permit snow days or how many excused absences it would allow a student in a given year.

porcelain     A hard, brittle material made by treating clay to a long heat treatment. The process, first perfected in Asia, came to be known as “china.” When treated before heating with a glaze, its surface can become impermeable, making it a good material for holding foods or liquids.

power plant     An industrial facility for generating electricity.

range     The full extent or distribution of something. For instance, a plant or animal’s range is the area over which it naturally exists. (in math or for measurements) The extent to which variation in values is possible. Also, the distance within which something can be reached or perceived.

renewable energy     Energy from a source that is not depleted by use, such as hydropower (water), wind power or solar power.

resilient     (n. resilience) To be able to recover fairly quickly from obstacles or difficult conditions.

risk     The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

sensor     A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly. (in biology) The structure that an organism uses to sense attributes of its environment, such as heat, winds, chemicals, moisture, trauma or an attack by predators.

short circuit     A low-resistance connection between two electrically conducting materials that unintentionally create a circuit. The condition causes the flow of an excessive current and may produce very high temperatures. It can potentially cause parts of the circuit to be destroyed (even explode).

space weather     Conditions on the sun, in the solar wind and within Earth’s upper atmosphere that can affect technologies on Earth and that have the potential to endanger human health. Triggering these weather events are the stream of plasma, or solar wind, emitted by the sun. In addition, there are clouds of material spewed by the sun, known as coronal mass ejections. Together, these can contribute to large magnetic and electrical storms in Earth’s upper atmosphere.

stellar     An adjective that means of or relating to stars.

stress     (in physics) Pressure or tension exerted on a material object.

substation     (in energy) A small, local facility whose primary function is to step down the voltage of current moving through high-voltage power lines. The new voltage — now less than 10,000 volts — can be distributed to homes and businesses.

terrorism     The use of threats or violence to compel people to do things against their will.

thermostat     A temperature sensor that allows a system to know when a change — either heating or cooling — is called for.

transmission     Something that is conveyed or sent along. (in mechanics) In a liquid-fueled vehicle, the machinery used to transfer power from the engine to the drive wheels. (In medicine) To spread a disease or toxic agent.

turbine     A device with extended arm-like blades (often curved) to catch a moving fluid — anything from a gas or steam to water — and then convert the energy in that movement into rotary motion. Often that rotary motion will drive a system to generate electricity.

voltage     A force associated with an electric current that is measured in units known as volts. Power companies use high-voltage to move electric power over long distances.

waste     Any materials that are left over from biological or other systems that have no value, so they can be disposed of as trash or recycled for some new use.

weather     Conditions in the atmosphere at a localized place and a particular time. It is usually described in terms of particular features, such as air pressure, humidity, moisture, any precipitation (rain, snow or ice), temperature and wind speed. Weather constitutes the actual conditions that occur at any time and place. It’s different from climate, which is a description of the conditions that tend to occur in some general region during a particular month or season.

wind turbine     A wind-powered device — similar to the type used to mill grain (windmills) long ago — used to generate electricity.


Report: Energy resilience solutions for the Puerto Rico grid. United States Department of Energy. June 2018, 59 pp.

Journal: J. Coignard et al. Clean vehicles as an enabler for a clean electricity grid. Environmental Research Letters. Vol. 13, May 16, 2018. doi: 10.1088/1748-9326/aabe97.

Report: A. Silverstein et al. A Customer-focused framework for electric system resilience. Grid Strategies LLC, May 2018, 76 pp.

Report: Magnetohydrodynamic electromagnetic pulse assessment of the continental U.S. electric grid: Voltage stability analysis. Electric Power Research Institute, December 20, 2017, 40 pp.

Report: G. Karagiannis et al. Power grid recovery after natural hazard impact. European Commission Joint Research Centre, December 5, 2017, 56 pp. doi: 10.2760/87402.

Journal:​ ​​A. Hansen ​​et​ ​al.​ ​ Security analysis of an advanced metering infrastructure.​ ​​ International Journal of Critical Infrastructure Protection.​ ​​Vol.​ ​18,​ ​September 2017, p. 3. doi:​ ​10.1016/j.ijcip.2017.03.004.

Further Reading