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Direct Current Podcast S2 E8: Holiday Lights, Redux
U.S. Department of Energy
U.S. Department of Energy


TRANSCRIPT - S2 E8: Holiday Lights, Redux


ALLISON LANTERO: So Matt, I’ve figured it out. There are two kinds of people around the holidays: people who like colored lights, and people who like white lights. Which are you?

MATT DOZIER: Uh, I don’t know, I’ve never really thought-

LANTERO: (interrupts, talking fast) I grew up in a home that did colored lights, but now my parents have a tree that can change from colored to white with the press of a button. It can even flash between the two every couple seconds!

DOZIER: Whoa, slow down!

LANTERO: Sorry, I just get so excited around the holidays!

DOZIER: I know, I remember! Hey, I’ve actually got a story that I think you’re really going to like. What if I told you those twinkling lights could soon be powering your online Christmas shopping?

LANTERO: Wait, really?! I love it! And after that, what do you say we replay our episode about holiday lights from season one?

DOZIER: Perfect. All that coming up after the break, stick around!


DOZIER: It’s the holiday season, the days are getting colder, and we’re starting to see festive lights twinkling pretty much everywhere you look.


DOZIER: It’s also the season of online shopping, when millions of people around the world go searching for digital deals and holiday gifts on their computers and smartphones.

DOZIER: All that traffic goes through data centers, which are essentially massive warehouses full of servers that move and process billions of bytes per second.

MIKE HANEY: Everything we do, everything we touch with our mobile apps connects to a data center. Every phone call. These are all requiring transactions in the data centers that are happening as you speak.

DOZIER: Mike Haney is a project manager for the Advanced Research Projects Agency-Energy, or ARPA-E. You may remember ARPA-E from season one of this podcast, when we profiled the fancy acronyms they give to their cutting-edge energy research programs.

DOZIER: I talked to Mike the day after Cyber Monday. It turned out to be the biggest online shopping day in U.S. history, with more than six and a half billion dollars in sales. And, for the first time, more than half of those sales came from mobile devices.

HANEY: The thing you carry in your pocket, we all carry in our pocket, is a huge source of energy usage. And I'm not talking about the battery in your phone, I'm talking about the other end.

DOZIER: The “other end” is the data centers. And this is where all those shopping transactions, online searches, social media posts and more start to add up to a whole lot of energy consumption.

HANEY: On the order of 3 percent of the power grid is dedicated to powering data centers. That's a large number all by itself, it's on the order of 12-15 gigawatts. What's more problematic, I think, is the growth that's anticipated.

HANEY: The demand, as you know, for use of data centers for everything from high-resolution selfies and cat videos to streaming through netflix, through all of the other applications we use is only growing.

DOZIER: On top of the rapid growth of mobile applications, there’s the “Internet of Things.” Estimates vary, but most experts predict that tens of billions of devices -- refrigerators, thermostats and the like -- will be connected by the year 2020.

DOZIER: With all of this, the traffic handled by data centers is going up exponentially -- and so is the energy they consume.

HANEY: Well, think about it. If you freeze technology at today's level, which is very high, if data centers are taking 3 percent of the grid, and the projections are that demand is going to go up by 10X, that's 30 percent of the grid, and that's not sustainable.

DOZIER: At the same time, the internet is rapidly approaching a physical cap on how much data you can move using metal wires.

HANEY: Wires have a sort of a fundamental limit to how much data per joule of energy they can carry. That's where we call a brick wall that we're going to hit. The computing chips are getting much more sophisticated and continue to do so, but the ability to feed them data and take data from them is going to be diminishing.

DOZIER: But don’t panic. One of the programs Mike manages is searching for a way around this digital “brick wall.” And in true ARPA-E style, its acronym game is on point.

HANEY: ENLITENED is an acronym. It's spelled E-N-L-I-T-E-N-E-D, and it stands for Energy-Efficient Lightwave Integrated Technology Enabling Networks that Enhance data centers. So I hope you agree, it's fairly inspired as an acronym.

DOZIER: The basic premise behind ENLITENED is using light instead of electricity to transfer data. It’s called “photonics.”

HANEY: Right. So with electrons they would travel on wires. With photons, they travel on waveguides. These waveguides are made of transparent material such as plastics or glass or silicon, and we can have very high data rates over waveguides.

DOZIER: You’ve probably heard of fiber optics, which use light to shuttle our searches and selfies around the world. They’re essentially the backbone of the internet.

DOZIER: Same concept here, but on a smaller scale, inside the vast warehouses of computing hardware that juggle all of our digital activities, from chatting to banking to ordering a new coffee maker with free two-day delivery.


KEREN BERGMAN: There is so much data behind that tiny little purchase that you just made that's crunched very quickly in the background. It's mind-boggling how it all works and actually works very well.

DOZIER: That’s Keren Bergman, she’s an electrical engineering professor at Columbia University. Keren leads a project funded by ENLITENED that’s looking at how photonics could transform our whole notion of how data centers work.

DOZIER: She also has a lot of firsthand experience with digital commerce.

BERGMAN: I do, I am the queen of online shopping. (LAUGHS) Self-declared. The self-declared queen.

DOZIER: Keren said a typical data center consists of three main parts. There’s the “compute,” which provides the processing power, the “memory,” where the data is stored, and the “interconnect.” This last part is the network that links everything in the data center -- all the chips and modules and servers. That’s the part that her project is focused on trying to improve using photonics.

BERGMAN: The question that's really interesting that we're addressing across the project, and ours in particular is, how can we apply this great communication technology of photonics within the data center to connect up all these resources in a more energy-efficient way than is currently done using electronics?

DOZIER: Let’s back up a second. What’s wrong with electronics?

DOZIER: Well, when you send an electrical signal over a metal wire, some of that energy is lost as heat. Also, the bandwidth is fixed, meaning that it can only carry so many ones and zeroes at a time. Photonic connections are faster, more flexible, and don’t waste nearly as much energy.

DOZIER: Much better, right? Except there’s a catch.

BERGMAN: We can say, OK, I'm just going to rip out all of the electronic wires and electronic switches and just replace them with optical switches. Why don't I just do that, and then I will have higher bandwidth and lower energy consumption? The fundamental problem is that unfortunately photons are very different than electrons. And so if I do that, things are just not going to work in the same way.

DOZIER: There’s another reason it doesn’t make sense to just swap out all the electronic connections for photonic ones: cost. Waveguides made of silicon and other materials are getting cheaper, but they’re still more expensive than standard metal wires.

DOZIER: Instead, Keren’s team is taking a more holistic approach. Columbia’s partners on the project include Berkeley Lab, academic institutions like the University of California Santa Barbara, and businesses like Cisco and Microsoft. Together, they’re working to reimagine the entire structure of data center networks to deliver big gains in energy efficiency.

BERGMAN: We're all used to computing capabilities as just eternally scaling, right? We have what used to be a supercomputer now in our handheld phone, and so on and so on. But energy doesn't go like that. It's not like every two years we have twice as much energy as we had 18 months ago, right?

DOZIER: With the help of some strategically placed photonic connections, Keren said the project is aiming to achieve a nearly three-fold jump in efficiency -- so, three times the performance for the same amount of energy. That’s not just for the network -- that’s for the entire data center.

DOZIER: All of the projects under the ENLITENED umbrella are working toward similar milestones, both in efficiency and speed of data centers. One goal is to slash the amount of energy needed to transfer one bit -- that’s the smallest unit of digital data -- by a factor of 10, from 10 picojoules to one picojoule.

DOZIER: In case you’re wondering, no, a “picojoule” isn’t a video game character.

HANEY: A joule is a fundamental unit of energy. One Google query takes about 1,000 joules, a kilojoule. And that's equivalent to operating a standard lightbulb for about 10 seconds. Very rough numbers. So, a picojoule is one times 10^-12. So divide by one with 12 zeroes and you get one picojoule per individual bit is the target.


DOZIER: Mike said ARPA-E has set an aggressive timeline for the program, which could start to pay dividends in the near future -- not just in data centers, but in emerging fields like high-performance computing. And as a professor with a background in photonics, he’s looking forward to getting his hands dirty.

HANEY: It’s a team effort. And we interact very closely with the project teams themselves. We have a very interactive, hands-on approach to managing our projects. It's great for people like me, technical people, because we just get right in the weeds with them (laughs), and it's fun.

DOZIER: It’s exciting technology, but it’s also incredibly important to the future of these things that serve as the foundation of our digital lives.

BERGMAN: Data centers have become, I believe, one of the most critical infrastructures to our society.

DOZIER: And as we take for granted the ever-increasing torrent of streaming video, turn-by-turn directions, social media posts and online purchases pouring into data centers, the need to adapt is only going to get more pressing.

BERGMAN: I think especially this time of year, it's a constant reminder of how dependent we are, and how much more dependent we will become going forward. I look at my teenage kids and to them, this is just part of life.


LANTERO: And now, let’s reach into the Direct Current archive and listen to everyone’s favorite energy-themed holiday poem…


NARRATOR: Twas a few weeks before Christmas…

VOICE 1: Hannukah!

VOICE 2: Kwanzaa!

VOICE 3: Festivus!

NARRATOR: Twas a few weeks before the holidays... at En-er-gee,

Allison and Katie were decorating their tree

KATIE WALSH: I strung up the lights, but hard as I tried,

Some of the strands would only light up on one side.

LANTERO: I plugged and unplugged, I wiggled the wire,

I twisted some bulbs and began to perspire

WALSH: I was ready to quit, to throw out my elf-hat,

NARRATOR: When along came Dan Wood saying,

DAN WOOD: Let me help with that!

(Classical music plays)

WOOD: I’ve studied these lights, and I know all their quirks.

Here check out this string, I’ll show you how it works.

These lights can show us how electric currents flow,

When the circuits are working, the bulbs how they glow!


WOOD: Now, there’s a filament inside of each incandescent,

That heats up and makes the bulb luminescent.


WOOD: When these lights are in a series, as these seem to be,

A single burnt filament can darken the tree.

WALSH: Cuz it breaks the circuit?

WOOD: Yes! That is quite right.

Electricity is blocked, which means there’s no light.

LANTERO: But what about strands that are partially lit?

Is there a problem within that circuit?

WOOD: The answer is yes, but there’s more to be said,

They’re wired in parallel, so just some are dead.

When multiple series are wired together,

They create longer strands, but don’t always work better.

WOOD: Wait, a filament breaks and the whole strand goes bust?

There’s gotta be a better way. Really, there must.

WOOD: There are! They’re called shunts, a helpful invention,

If a filament breaks it preserves the connection.

LANTERO: Then why aren’t they working? Are these just defective?

WOOD: Possibly. Or, from another perspective,

If dead lights aren’t replaced, the rest burn out faster,

That’s a surefire route to a holiday disaster.

WALSH: How do you know if the lights are all dead?

Or if just one single bulb is darkening the thread?

WOOD: Well, first you should make sure that each bulb is in tight,

Give each one a twist, and see if the strand lights.

If nothing will light, a fuse might’ve blown,

Which you can replace all on your own.

There’s a miniature door at the end of the wire,

The fuse nestled inside protects you from fire.

Now slide the door open, and if it’s all black,

Pop in a new one, and then slide it back.

LANTERO: So we looked at the fuses, and tested each shunt,

And also embarked on a loosened light hunt.

But when we tried it again, some still didn’t light.

WALSH: This is taking forever. We’ll be here all night!

WOOD: Now don’t worry Katie, there’s more tricks up my sleeve,

You really should hang up some new LEDs.

LED lights are stronger, use less energy;

They also last longer on our homes and our trees.

(Sound of joyful bells)

NARRATOR: From out of his sleeve came a long string of lights,

He plugged it right in, and the tree shined so bright!

The lights how they sparkled! The tree looked so merry!

Dan winked and he smiled, like a sugar plum fairy.

They heard him exclaim ‘ere he walked out of sight

WOOD: Happy holidays to all and to all working lights!

WALSH: Now our tree’s covered in light emitting diodes,

Let’s thank some folks for help on this episode.

LANTERO: Direct Current’s produced by me, Simon and Matt,

Art by Cort, help from Paul, Atiq, Ernie and Pat.

WALSH: Thanks to Marissa  and Team Public Affairs,

For all of their edits, critiques and blank stares.

LANTERO: A big thank-you to Katie, my favorite guest host,

And to Dan Wood, for teaching us the most.

WALSH: Direct Current is from the Department of Energy,

Produced out of our office in Washington D.C.

LANTERO: is where you should go,

To get more information about this very show.

LANTERO: Thanks for all your help, Katie.

WALSH: Anytime, Allison.

LANTERO: Think it’s time to take the Santa hat off now?

WALSH: No, this is never coming off.

DOZIER: And we can’t end the show without giving a hand,

To Peebles Squire, Mike Haney & Keren Bergman.

LANTERO: Thanks for listening!


We're keeping the season merry and bright with a show about data and holiday lights!

Ever thought about how big a role data centers play in your life? From searching to streaming to shopping, these critical pieces of infrastructure provide the foundation for our digital world -- and they need an upgrade.

Learn how an ARPA-E program is using light-powered technology to boost data center performance and energy efficiency for the future.

Also, we revisit our favorite energy-themed holiday poem from season 1! Still curious about how holiday lights work? Check out our infographic for more!