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