Skip to main content

Energy

Wait, So Where Will Urbanites Charge Their EVs?

Homeowners with garages can easily charge their electric cars, but not apartment dwellers. Here's what it'll take to get plugs everywhere in cities.

Europe Is in the Middle of a Messy Nuclear Slowdown

Germany has almost finished phasing out nuclear plants, and aging infrastructure is leading neighbors down the same path. But will green energy goals suffer?

The US Inches Toward Building EV Batteries at Home

In an effort to reduce dependency on hard-to-source cobalt and Chinese manufacturing, US makers are finally getting into the cathode business.

Distance Wireless Charging Made a Minor Comeback at CES 2022

The potential of truly wire-free power is exciting, but tangible products remain elusive.

Facebook’s Data Center Plans Rile Residents in the Netherlands

The country has become a magnet for Big Tech facilities, but locals say they will syphon away all their green energy. 

Gravity Could Solve Clean Energy’s One Major Drawback

Finding green energy when the winds are calm and the skies are cloudy has been a challenge. Storing it in giant concrete blocks could be the answer.

This New Tech Cuts Through Rock Without Grinding Into It

A startup called Petra uses super-hot gas to penetrate bedrock. The method could make it cheaper to move utilities underground—and make electric lines safer. 

Renewable Energy Is Great—but the Grid Can Slow It Down

Many solar and wind projects face a problem: getting the energy from where it’s made to where it’s needed. 

Your Rooftop Garden Could Be a Solar-Powered Working Farm

A new scientific field proposes an idea that could help generate food and energy while reducing a building's cooling costs.

This Dam Simple Trick Is a Big Green Energy Win

Only a small fraction of dams actually produce electricity. Transforming them them into hydropower plants might stop new ones from being built.

Finally, a Practical Use for Nuclear Fusion

Researchers used the roiling temperatures of an experimental fusion reactor for a surprising purpose—testing heat shield materials for spacecraft.

Sodium Batteries May Power Your New Electric Car

As EV sales increase, supplies of lithium may get tight. So some companies are incorporating cells with sodium, which provides almost as big a charge. 

Cars Are Going Electric. What Happens to the Used Batteries? 

Used electric vehicle batteries could be the Achilles' heel of the transportation revolution—or the gold mine that makes it real.

These Batteries Can't Power a Car—but They Can Light a City

Entrepreneurs are devising innovative ways to reuse spent electric vehicle batteries. One promising idea is storing power from solar and wind farms.

The Grid Isn’t Ready for the Renewable Revolution

The massive deployment of wind and solar will turn you, the humble homeowner, into a critical actor in the operation of the US power grid.

An Outdated Grid Has Created a Solar Power Economic Divide

Utilities have upgraded the infrastructure for rooftop power in richer neighborhoods, but low-income areas don't have the same capacity.

Want to Slash Carbon Emissions? Start With These Power Plants

The worst 5 percent of energy producers account for almost 75 percent of the sector’s emissions.

Biden Wants More EVs on Roads. What About Charging Stations?

The president called for 40 percent of new cars to be electric by 2030. But motorists still fret about running out of juice—even if it rarely happens.

Can You Recycle a Hard Drive? Google Is Trying to Find Out

Rare-earth magnet recycling could reduce the need to mine for more resources, leading to more sustainable data centers.

Extreme Heat Could Also Mean Power and Water Shortages

An extraordinary drought in the West, plus dry lakes and reservoirs, mean there will be less water for farms, hydroelectric energy, and home users.

How to Prepare for the Robot Apocalypse (If You’re a Robot)

In the Netflix show The Mitchells vs. the Machines, robots are planning to blast all of humanity into outer space. How much time and energy will that take?

Why Utilities Want to Control Your Smart Thermostat

Don’t mess with Texans’ air conditioning. Here’s why some customers in the state had their thermostats remotely controlled.

High-Energy Cosmic Ray Sources Get Mapped for the First Time

They twist and turn on their way to Earth, which has made it nearly impossible to identify the colossal monsters that create them.

How Many Homes Could You Power With Free Doughnuts?

Should you get a COVID vaccine? Yes, it will protect you AND protect others to help us move past this pandemic so we can get back to a more normal life. But wait! If you get vaccinated, you can also get a doughnut! At least that's the deal that Krispy Kreme Doughnuts is offering. Once you get your vaccine, you get a doughnut. Oh, it's not just one doughnut—it's one doughnut every day. That's a lot of doughnuts. OK, so how about some physics estimations to go along with your tasty doughnut? Let's say that all the Americans that have a COVID vaccine get (and eat) one doughnut a day. Of course eating food gives you energy to do stuff—that's how food works. So, suppose that all these humans eat their doughnut and then use the extra energy to peddle a stationary bike. All of these bikes are then connected to generators so that they feed into the power grid. What kind of power output would this produce? The first thing we need is the number of doughnuts a day. According to the Center for Disease Control (CDC) 63 million Americans have been fully vaccinated so far (as of April 7 2021). Oh, don't worry too much about the numbers—I'm going to do all my calculations in python so that you can change the values if that makes you happy. I'm also going to assume that all these people get their doughnut—every day. Next, I need to know the amount of energy per doughnut. According to Krispy Kreme's site, a plain glazed doughnut is 190 Calories. But what the heck is a Calorie? Well, [the original calorie was created to describe changes in thermal energy for different substance](https://en.wikipedia.org/wiki/Calories. Then, later people used it to measure the amount of chemical energy your body can get from eating food. However, there is a problem. For some reason, all food labels list stuff in Calories—but these are really kilocalories. So, that doughnut has 190,000 calories. I guess it just sounds like it's too big of a number for people to consider eating. There is another unit of energy—the joule. Since this is the preferred unit of energy for physicists, I'm going to use it. To convert between units, 1 calorie is equal to 4.184 joules. But what does this have to do with your everyday life? Let's consider something you might do without too much effort. Suppose you have a textbook on the floor and you pick it up to put it on a table. Since you are exerting a force on the book over some distance, you have to change the gravitational potential energy of that book. The change in gravitational potential energy is equal to the mass of the book (about 1 kilogram) multiplied by the local gravitational field (g = 9.8 N/kg) and then multiplied by the change in height (about 1 meter). This will give a change in energy of about 10 joules. So that gives you a rough feeling for the amount of energy in a joule. But what about power? Power is the rate of energy change. It tells you how fast you use energy. As an equation, it looks like this:

defpower

In this expression, if ΔE is the change in energy in units of joules and Δt is the time interval in seconds then the power will be in units of watts. We are almost ready to calculate the vaccine doughnut power. We just need one more estimation—the efficiency. When a human eats a doughnut, only some of the chemical energy goes all the way into useful energy. Also, with a stationary bike generator some of the energy the human uses to push the pedals also goes into heating up some of the moving parts. In the end, only a percentage of the energy goes into electrical energy. This percentage is the efficiency. I'm just going to make a rough guess that the process of doughnut eating to electrical energy is 25 percent efficient. That's it. I just need to take the number of doughnuts per day and convert that energy to joules and then divide by the length of a day (in seconds). Oh, and multiply by the efficiency. Here's what I get. Note: this is actual python code. You can see my calculations and even change them if you like.

pythonpower

You can see that for each human, it's just a measly 2 watts of power. That's around the power output for a smart phone (power values vary based on use). However, once you include all the vaccinated people we get up to 144 Megawatts. In 2019, the average household power was about 1200 watts. That means that you could use all these doughnuts to run 120 thousand homes. Oh, AND you get vaccinated—that's a win.

More Great WIRED Stories