Self-Powered Self-Powered ProcessorsProcessors

Andrew Putnam, Luis CezeUniversity of Washington

Computer Science & Engineering

Bryna HazeltonUC Santa Cruz

Dept. of Physics

What if processors powered themselves?

No need to cluster around electrical outlets at conferences

AASS

PPLL

OOSS

Use all of those power pins for something useful

Run all the speculative and helper threads you want

Stop worrying about power management

How would this change…Computing in the 3rd World?

Remote sensing and data collection?

Cost and management of data centers, cloud computing?

Nano-scale machines?

Energy Independence! Researchers lead the way with self-powered processors

I’m graduating: offer me a job and get your company logo here!

On-Chip Power GenerationChip-Scale nuclear reactors

FissionAlpha decay

Use heat energy from the environmentSilicon Solid-state “Wiggler”

Chip-Scale Nuclear PowerGlow-in the Dark Processors

Chip-Scale Nuclear Reactor

Radioactive isotopes have incredible energy densities

Uranium-235: 11.4g (0.60 cm3) provides 50W for 10 years

Stirling EngineHot chamber absorbs heat energy from

surroundings

Air flows from hot chamber to cold

Cold chamber cools, compresses air

Efficiency has recently jumped from 5% to 38%

CPU

Fission Generator Thermally isolated by 5mm

Aerogel

Lithium-6 bath converts neutrons to gamma rays

50W continuous power

AerogelAerogel

Hot Chamb

er

Hot Chamb

er

Fission Chamber

3cmSurgeon General Warning:

Gamma rays can be hazardous to your health. These

processors should come nowhere near any living

organism.

Alpha Decay GeneratorHeat from radioactive alpha decay from larger

decay chamber

Alpha decay is easilyshielded

Polonium-208, 21053W for 5 years

Plutonium-23855W for 100+ years

Strontium-9035 W for 40 yearsRequires 1cm lead shielding to block gamma rays

CPUAerogelAerogel

Hot Chamb

er

Hot Chamb

er

DecayChamber

9cm

Silicon “Wiggle” GeneratorShake it like a Poloroid Picture

Spring – Capacitor Circuit

SpringSpring

BatteryBattery

CapacitorCapacitor

Spring – Capacitor Circuit Charge builds up on capacitor

plates

Spring – Capacitor Circuit Charge builds up on capacitor

plates

As charge builds, plates are attracted to each other

Spring – Capacitor Circuit Charge builds up on capacitor

plates

As charge builds, plates are attracted to each other

As plates get closer, attractive force grows

Spring – Capacitor Circuit Charge builds up on capacitor

plates

As charge builds, plates are attracted to each other

As plates get closer, attractive force grows

Plates contact, and charges move across the plates

Spring – Capacitor Circuit Charge builds up on capacitor

plates

As charge builds, plates are attracted to each other

As plates get closer, attractive force grows

Plates contact, and charges move across the plates

Spring recoils, disconnecting capacitor plates

Recoil

Spring – Capacitor Circuit Charge builds up on capacitor

plates

As charge builds, plates are attracted to each other

As plates get closer, attractive force grows

Plates contact, and charges move across the plates

Spring recoils, disconnecting capacitor plates

Charges regenerate

Spring – Capacitor Circuit Charge builds up on capacitor

plates

As charge builds, plates are attracted to each other

As plates get closer, attractive force grows

Plates contact, and charges move across the plates

Spring recoils, disconnecting capacitor plates

Charges regenerate

Cycle begins again

CapacitorCapacitor

SpringSpring

BatteryBatteryp-dopedp-doped

AnvilAnvil

n-dopedn-dopedHammerHammer

CapacitorCapacitor

CantileverCantilever

DepletioDepletion n

RegionRegion 0.6V0.6V

Charge

p-dopedp-dopedAnvilAnvil

n-dopedn-dopedHammerHammer

Attraction

Discharge

Recoil

Energy Generation Charge carriers are

thermally regenerated

Phonon lattice vibration (a.k.a. “heat”) kicks electrons to higher-energy state

So the energy comes from the ambient heat around the device (heat bath)

Device will operate until freezeout temperature -173°C for Silicon

-+

-+

DetailsPiezoelectric converts motion to electricity

Very high conversion efficiency (50%-90%)

Each device: 5 nW

1 mm3 : 2.5 W (mobile processor)

40 mm3 : 100 W (high-performance processor)

1 m3 : 2.5 GW (medium-sized city)* *- requires 100°C of heat energy per second

1 ft3 : 3.7°C / second air conditioner @ 46 MW

Solar cells: 4.8 GW / m3 (170 W/m2 0.35 mm thick)

Powering Nano-Devices

MEMS / NEMS Device

2200 μm

6100μm

10 μm

Powering Nano-Devices

Thank YouQuestions?

2nd Law of Thermodynamics

"Every physicist knows what the first and second laws mean, but it is my experience that no two physicists agree on them." -- Clifford Truesdell

2nd law is a statistical law based on classical mechanics

The applicability of the 2nd Law to quantum mechanical domains is hotly debated

This isn’t a perpetual motion machine – it will stop working with the heat death of the universe

Energy DensitySolar cells: 170 W / m2

0.35 mm thick

Power density = 4.8 GW / m3

Stirling EngineHot chamber absorbs heat energy from

surroundings

Air flows from hot chamber to cold

Cold chamber cools, compresses air

GapGap

CantileverCantilever

DepletioDepletion n

RegionRegionp-dopedp-doped

AnvilAnvil

n-dopedn-dopedHammerHammer