Self-Powered Processors Andrew Putnam, Luis Ceze University of Washington Computer Science & Engineering Bryna Hazelton UC Santa Cruz Dept. of Physics

What if processors powered themselves? No need to cluster around electrical outlets at conferences ASASPL OSPL OSASASPL OSPL OS 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 3 rd 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 Generation Chip-Scale nuclear reactors Fission Alpha decay Use heat energy from the environment Silicon Solid-state “Wiggler”

Chip-Scale Nuclear Power Glow-in the Dark Processors

Chip-Scale Nuclear Reactor Radioactive isotopes have incredible energy densities Uranium-235: 11.4g (0.60 cm 3 ) provides 50W for 10 years

Stirling Engine Hot 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 Aerogel Hot Chamber Fission Chamber Cold Chamber 3cm Surgeon General Warning: Gamma rays can be hazardous to your health. These processors should come nowhere near any living organism.

Alpha Decay Generator Heat from radioactive alpha decay from larger decay chamber Alpha decay is easily shielded Polonium-208, W for 5 years Plutonium W for 100+ years Strontium W for 40 years Requires 1cm lead shielding to block gamma rays CPU Aerogel Hot Chamber Decay Chamber Cold Chamber 9cm

Silicon “Wiggle” Generator Shake it like a Poloroid Picture

Spring – Capacitor CircuitSpringBattery Capacitor

Charge builds up on capacitor plates

Spring – Capacitor Circuit Charge builds up on capacitor plates As charge builds, plates are attracted to each other Attraction

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 Attraction

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 Attraction 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

Capacitor Spring Battery p-dopedAnvil n-dopedHammer

Capacitor Cantilever Depletion Region 0.6V

Charge p-dopedAnvil n-dopedHammer

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 E-Field

Details Piezoelectric converts motion to electricity Very high conversion efficiency (50%-90%) Each device: 5 nW 1 mm 3 : 2.5 W (mobile processor) 40 mm 3 : 100 W (high-performance processor) 1 m 3 : 2.5 GW (medium-sized city)* * - requires 100°C of heat energy per second 1 ft 3 : 3.7°C / second air 46 MW Solar cells: 4.8 GW / m 3 ( 170 W/m mm thick)

Powering Nano-Devices Duracell MEMS / NEMS Device 2200 μm 6100μm 10 μm

Powering Nano-Devices

Thank You Questions?

2 nd 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 2 nd law is a statistical law based on classical mechanics The applicability of the 2 nd 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 Density Solar cells: 170 W / m mm thick Power density = 4.8 GW / m 3

Stirling Engine Hot chamber absorbs heat energy from surroundings Air flows from hot chamber to cold Cold chamber cools, compresses air

Gap Cantilever Depletion Region p-dopedAnvil n-dopedHammer