
Can you power a house with a ShakeWeight?
Season 3 Episode 9 | 6m 52sVideo has Closed Captions
Using a ShakeWeight, how long would it take to power a house for a day?
Using a ShakeWeight, how long would it take to produce enough energy to power a house for a day? Are we making progress toward clean and alternative energy sources?
Problems playing video? | Closed Captioning Feedback
Problems playing video? | Closed Captioning Feedback

Can you power a house with a ShakeWeight?
Season 3 Episode 9 | 6m 52sVideo has Closed Captions
Using a ShakeWeight, how long would it take to produce enough energy to power a house for a day? Are we making progress toward clean and alternative energy sources?
Problems playing video? | Closed Captioning Feedback
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Learn Moreabout PBS online sponsorshipRobert, are you ready?
So this is Robert.
He's my roommate.
Hi.
He also happens to be a physicist.
So Robert, this is my device, co-designed and made by Kyle.
Have you heard of a ShakeWeight?
I have not heard of the-- what?
You shake it like this and get a good workout.
All right.
Yeah-- so we modified this ShakeWeight so that there's a magnet connected to a rod.
And the magnet goes back and forth between this coil of wire.
And the coil is connected to an LED so that-- do you want to try it?
All right, I'll try it.
OK, hold on.
Hold on.
Why are you putting on safety goggles?
Oh, you see it?
Yep.
It's working!
Thank you for demonstrating.
In your expert opinion, how cool is this invention?
It's definitely very pretty, especially here with the reflecting surfaces.
Oh, that came with the ShakeWeight.
OK, thank you, Robert.
I think he liked it.
The purpose of this modified ShakeWeight is to see how much electrical energy we can make, using electromagnetic induction and starting out with kinetic energy.
Then the last thing I want to figure out is, how long would it take, using this device, to produce enough energy to power a house for an entire day?
I'm going to need a way to measure the energy.
You guys know that I'm pretty excited about science.
I want us to send things to Mars.
And not just things that rhyme with Mars-- Elon.
But also, I want us to be responsible earthlings.
If we want to curb our carbon emissions, we're going to have to change the way that we produce and use energy.
Here's my contribution.
I promise this is all going to tie back together later in the video.
But in the meantime, now we need a way to figure out how much power we're outputting with this.
I'm going to replace the LED with a resistor and Arduino that I've programmed to show the voltage across the resistor.
Ha!
Resistors-- and then we can use that voltage in the resistor to figure out the power.
Now, the way that we're getting power is the cool part here.
The only thing we have is a coil of wire and a permanent neodymium magnet on a rod, going back and forth through the PVC pipe.
And now, Lenz's law here tells us that, when you have a changing magnetic field, like that of a moving permanent magnet, you can induce an electromotive force in a coil of wire.
An electromotive force is like it pushes the electricity.
In our case, the electricity can flow.
So we get a current in the coil.
That's what lights up the LED.
There's no battery, no outlet, no source of power besides what we've made here.
Heh, time to pretend I know what I'm doing.
Yah!
It works.
I made this.
Go talk with the more scripted organized Diana about clean energy.
And then come back.
So I care a lot about this issue of clean energy and where it comes from.
Or at least, that's what I say.
Now, if I really cared, I would be an expert on the subject, right?
So I have this idea to quiz myself of questions about the clean energy industry and where we stand in our progress.
But I swear, I came up with the questions off the top of my head.
And I didn't do any research before I answered them.
This is a dangerous thing to do on the internet.
I totally suggest that you play along.
And I would love it if you put your answers in the comments.
OK, first question-- what percentage of energy in the US comes from clean energy?
I think this is the most important question.
I guessed 35%.
I don't even know if that's low or high.
I don't know.
The answer is, 10% of US energy, 15% of US electricity is from renewables.
Ooh!
OK, the difference in numbers here-- the 10% versus the 15%-- comes from the fact that not all of our energy is used toward electricity production.
In fact, most of it's not.
Electric power is only 39% of energy use in the US.
Biggest one after that is transportation, which is actually 29% of all of our energy.
Industrial is about 22%.
Factories use a lot of energy.
And then residential-- 6%.
And commercial is 4%.
So of our electrical power, it's higher.
It's about 15%.
And then of our total energy production, it's 10%, which makes sense.
Until we have electric cars, it's harder to do transportation with clean energy.
You need to worry about storage.
We've got a long way to go.
I feel like that's depressing.
I'm going to draw a graph.
I'm going to graph out since-- I don't know-- like, 1960, say, until now, what I think the percentage energy usage has looked like and then compare it to the real graph.
OK, so here's my graph.
And the real graph-- whoa-- 1990s, what were you doing?
But yeah, OK.
This is good news.
Let's compare the two graphs.
So this means that I underestimated clean energy in the early decades, because I forgot about hydroelectric.
But looking at the present day, we're making progress much faster than I thought.
Look at that slope!
Yeah, that's good.
It means that we're making quick progress in the technology.
Whoo-- OK.
The last question that I didn't guess, but I looked up, because I was curious during this quiz is, how much energy are we using total in the United States?
Again, we've got transportation.
We've got industry.
We got all these different sectors using energy.
In the US, we use $28 trillion kilowatt hours per year.
Ugh!
And that's going to go up by 20% by 2040.
So it's going to be 35 trillion kilowatt hours per year.
That's 80 trillion kilowatt hours per day.
That's 80 billion people playing Mario Kart for 10 hours a day.
We don't even have 80 billion people on the planet.
These are mind-boggling numbers.
And finally, if you shake the ShakeWeight flashlight, you can produce-- OK, final calculation.
The average power produced by the ShakeWeight is-- drumroll-- 0.004 watts.
Yes!
So given that a house uses 30 kilowatt hours a day, it would take 7,500,000 hours to produce enough energy to power a house for a day.
Oh, what?
7.5 million-- that's 312,000 days-- 856 years of constantly shaking the ShakeWeight to produce energy for every single waking minute of your day.
Well, I give up.
So I'd say, the biggest surprise to me was the magnitude of these numbers and how little electricity I was able to produce with the ShakeWeight.
Of course, most of it was going into heating up my muscles.
It wasn't a very efficient system.
And obviously, I was way too optimistic on our progress so far toward clean energy.
But I was a lot less optimistic on the trend that we've made.
So that means that we're making progress fast.
And we can make progress fast.
And with minds like yours-- creative minds that are working to improve clean energy technologies to come up with new ways of improving renewables-- I've got a lot of hope for the future.


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