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  • The electricity powering the lights in this theater

  • was generated just moments ago.

  • Because the way things stand today,

  • electricity demand must be in constant balance

  • with electricity supply.

  • If in the time that it took me to walk out here on this stage,

  • some tens of megawatts of wind power

  • stopped pouring into the grid,

  • the difference would have to be made up

  • from other generators immediately.

  • But coal plants, nuclear plants

  • can't respond fast enough.

  • A giant battery could.

  • With a giant battery,

  • we'd be able to address the problem of intermittency

  • that prevents wind and solar

  • from contributing to the grid

  • in the same way that coal, gas and nuclear do today.

  • You see, the battery

  • is the key enabling device here.

  • With it, we could draw electricity from the sun

  • even when the sun doesn't shine.

  • And that changes everything.

  • Because then renewables

  • such as wind and solar

  • come out from the wings,

  • here to center stage.

  • Today I want to tell you about such a device.

  • It's called the liquid metal battery.

  • It's a new form of energy storage

  • that I invented at MIT

  • along with a team of my students

  • and post-docs.

  • Now the theme of this year's TED Conference is Full Spectrum.

  • The OED defines spectrum

  • as "The entire range of wavelengths

  • of electromagnetic radiation,

  • from the longest radio waves to the shortest gamma rays

  • of which the range of visible light

  • is only a small part."

  • So I'm not here today only to tell you

  • how my team at MIT has drawn out of nature

  • a solution to one of the world's great problems.

  • I want to go full spectrum and tell you how,

  • in the process of developing

  • this new technology,

  • we've uncovered some surprising heterodoxies

  • that can serve as lessons for innovation,

  • ideas worth spreading.

  • And you know,

  • if we're going to get this country out of its current energy situation,

  • we can't just conserve our way out;

  • we can't just drill our way out;

  • we can't bomb our way out.

  • We're going to do it the old-fashioned American way,

  • we're going to invent our way out,

  • working together.

  • (Applause)

  • Now let's get started.

  • The battery was invented about 200 years ago

  • by a professor, Alessandro Volta,

  • at the University of Padua in Italy.

  • His invention gave birth to a new field of science,

  • electrochemistry,

  • and new technologies

  • such as electroplating.

  • Perhaps overlooked,

  • Volta's invention of the battery

  • for the first time also

  • demonstrated the utility of a professor.

  • (Laughter)

  • Until Volta, nobody could imagine

  • a professor could be of any use.

  • Here's the first battery --

  • a stack of coins, zinc and silver,

  • separated by cardboard soaked in brine.

  • This is the starting point

  • for designing a battery --

  • two electrodes,

  • in this case metals of different composition,

  • and an electrolyte,

  • in this case salt dissolved in water.

  • The science is that simple.

  • Admittedly, I've left out a few details.

  • Now I've taught you

  • that battery science is straightforward

  • and the need for grid-level storage

  • is compelling,

  • but the fact is

  • that today there is simply no battery technology

  • capable of meeting

  • the demanding performance requirements of the grid --

  • namely uncommonly high power,

  • long service lifetime

  • and super-low cost.

  • We need to think about the problem differently.

  • We need to think big,

  • we need to think cheap.

  • So let's abandon the paradigm

  • of let's search for the coolest chemistry

  • and then hopefully we'll chase down the cost curve

  • by just making lots and lots of product.

  • Instead, let's invent

  • to the price point of the electricity market.

  • So that means

  • that certain parts of the periodic table

  • are axiomatically off-limits.

  • This battery needs to be made

  • out of earth-abundant elements.

  • I say, if you want to make something dirt cheap,

  • make it out of dirt --

  • (Laughter)

  • preferably dirt

  • that's locally sourced.

  • And we need to be able to build this thing

  • using simple manufacturing techniques and factories

  • that don't cost us a fortune.

  • So about six years ago,

  • I started thinking about this problem.

  • And in order to adopt a fresh perspective,

  • I sought inspiration from beyond the field of electricity storage.

  • In fact, I looked to a technology

  • that neither stores nor generates electricity,

  • but instead consumes electricity,

  • huge amounts of it.

  • I'm talking about the production of aluminum.

  • The process was invented in 1886

  • by a couple of 22-year-olds --

  • Hall in the United States and Heroult in France.

  • And just a few short years following their discovery,

  • aluminum changed

  • from a precious metal costing as much as silver

  • to a common structural material.

  • You're looking at the cell house of a modern aluminum smelter.

  • It's about 50 feet wide

  • and recedes about half a mile --

  • row after row of cells

  • that, inside, resemble Volta's battery,

  • with three important differences.

  • Volta's battery works at room temperature.

  • It's fitted with solid electrodes

  • and an electrolyte that's a solution of salt and water.

  • The Hall-Heroult cell

  • operates at high temperature,

  • a temperature high enough

  • that the aluminum metal product is liquid.

  • The electrolyte

  • is not a solution of salt and water,

  • but rather salt that's melted.

  • It's this combination of liquid metal,

  • molten salt and high temperature

  • that allows us to send high current through this thing.

  • Today, we can produce virgin metal from ore

  • at a cost of less than 50 cents a pound.

  • That's the economic miracle

  • of modern electrometallurgy.

  • It is this that caught and held my attention

  • to the point that I became obsessed with inventing a battery

  • that could capture this gigantic economy of scale.

  • And I did.

  • I made the battery all liquid --

  • liquid metals for both electrodes

  • and a molten salt for the electrolyte.

  • I'll show you how.

  • So I put low-density

  • liquid metal at the top,

  • put a high-density liquid metal at the bottom,

  • and molten salt in between.

  • So now,

  • how to choose the metals?

  • For me, the design exercise

  • always begins here

  • with the periodic table,

  • enunciated by another professor,

  • Dimitri Mendeleyev.

  • Everything we know

  • is made of some combination

  • of what you see depicted here.

  • And that includes our own bodies.

  • I recall the very moment one day

  • when I was searching for a pair of metals

  • that would meet the constraints

  • of earth abundance,

  • different, opposite density

  • and high mutual reactivity.

  • I felt the thrill of realization

  • when I knew I'd come upon the answer.

  • Magnesium for the top layer.

  • And antimony

  • for the bottom layer.

  • You know, I've got to tell you,

  • one of the greatest benefits of being a professor:

  • colored chalk.

  • (Laughter)

  • So to produce current,

  • magnesium loses two electrons

  • to become magnesium ion,

  • which then migrates across the electrolyte,

  • accepts two electrons from the antimony,

  • and then mixes with it to form an alloy.

  • The electrons go to work

  • in the real world out here,

  • powering our devices.

  • Now to charge the battery,

  • we connect a source of electricity.

  • It could be something like a wind farm.

  • And then we reverse the current.

  • And this forces magnesium to de-alloy

  • and return to the upper electrode,

  • restoring the initial constitution of the battery.

  • And the current passing between the electrodes

  • generates enough heat to keep it at temperature.

  • It's pretty cool,

  • at least in theory.

  • But does it really work?

  • So what to do next?

  • We go to the laboratory.

  • Now do I hire seasoned professionals?

  • No, I hire a student

  • and mentor him,

  • teach him how to think about the problem,

  • to see it from my perspective

  • and then turn him loose.

  • This is that student, David Bradwell,

  • who, in this image,

  • appears to be wondering if this thing will ever work.

  • What I didn't tell David at the time

  • was I myself wasn't convinced it would work.

  • But David's young and he's smart

  • and he wants a Ph.D.,

  • and he proceeds to build --

  • (Laughter)

  • He proceeds to build

  • the first ever liquid metal battery

  • of this chemistry.

  • And based on David's initial promising results,

  • which were paid

  • with seed funds at MIT,

  • I was able to attract major research funding

  • from the private sector

  • and the federal government.

  • And that allowed me to expand my group to 20 people,

  • a mix of graduate students, post-docs

  • and even some undergraduates.

  • And I was able to attract really, really good people,

  • people who share my passion

  • for science and service to society,

  • not science and service for career building.

  • And if you ask these people

  • why they work on liquid metal battery,

  • their answer would hearken back

  • to President Kennedy's remarks

  • at Rice University in 1962

  • when he said -- and I'm taking liberties here --

  • "We choose to work on grid-level storage,

  • not because it is easy,

  • but because it is hard."

  • (Applause)

  • So this is the evolution of the liquid metal battery.