Off-world Power Generation Research

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Current conclusions

  • Use a satellite in low-earth sun-synchronous polar orbit. - for a Nevada-sized array?
  • Use lasers for power transmission not microwaves.
  • Use batteries for storage not capacitors - perhaps not (see note below)
  • Use low-power laser handshaking for safety cutoff.
  • Use best-practice cyber-security.

Earth orbits and other locations in space

  • earth to moon: 238,900 miles
  • there are four lagrange points that provide constant sun exposure at predictable locations
  • l1 to earth/moon: 1 million miles
  • A geosynchronous orbit takes one sidereal day, and is 35,786 km (22,236 mi) above the Earth's surface. Those closer to Earth orbit faster than Earth rotates, so from Earth, they appear to move eastward while those that orbit beyond geosynchronous distances appear to move westward.
  • other interesting earth orbits: low goes across poles, medium used by GPS, high is slow and crawls west, Molniya spends more time away from equator; relative distances diagram
  • sun-synchronous orbits that "ride the terminator" (the line that separates night and day, aka "dawn/dusk orbit") are low-earth polar orbits that maintain constant solar exposure. They cross many locations on the earth throughout the year - this guy KNOWS ORBITS, lots to learn here - sun-sync video example - scientific satellites that use this orbit include Yohkoh, TRACE, Hinode and PROBA2
  • Is there a sun-synchronous orbit that frequently passes over predictable locations on Earth's surface? That would be ideal for our purpose.

These are therefore probably less useful:

  • <Earth> <-clearsky-burst-laser-- <L1 solar array>
  • <Earth> <-microwave-- <Earth-orbit satellite> <-laser-- <Earth's moon> <-laser-- <L1 solar array>
  • <Earth> <-clearsky-burst-laser-- <Earth's moon> <-laser-- <L1 solar array>
  • <Earth-orbit satellite> <- <Earth's moon>
  • <Earth's moon> <- <Earth-Sol Lagrange-point solar array>

Power 101

Free-space power transfer

  • the sun primarily produces visible light (not microwaves or gamma...)
  • laser transmission is more efficient than microwave, except where earth's atmosphere interferes
  • current status: A Gigawatt-range microwave system would weigh ~80,000 tons (prohibitively expensive) more lots more
  • Solar cell efficiency - in 40 years we've gone from 22% to 46% efficiency
  • Laser transmit antenna in space: 1 meter diameter per GW
  • Receive: Several hundred meters across
  • Wireless Power Transmission - Japan's JAXA's working notes

Working Systems

NASA 2009 Power Beaming Competition

LaserMotive charging an unmanned drone

space elevator, and its power beaming need

  • Attempting this challenge requires that the participating teams would excel at laser optics, photovoltaics, electrical and mechanical engineering, and overall system design. The vehicles must be lightweight yet powerful. The laser beams must be well focused while tracking the climbers, and the climbers must be adept at converting them back into electricity and then into mechanical power. If you think this sounds complicated, you're right - out of about 40 teams that tried their hand at the challenge, only 3 made it to the final challenge.

Laser Basics

Coupled PV cells and Lasers

Often called Power Over Fiber.

MH GoPower (MHGP) produces a high-performance silicon-based vertical multijunction (VMJ) PV cell that enables high-wattage laser power transmission. See here.

Preliminary test data is shown for a 0.78 cm/sup 2/ VMJ cell with 40 series connected junctions producing 31.8 watts at 25.5 volts at near 2500 suns AM1.5 intensity (40.4 watts per cm/sup 2/ output at 211 watts per cm/sup 2/ input with an estimated efficiency near 20%).

Powerlight has free-space power beaming tech. LaserMotive has previously demonstrated power beaming systems with a receiver-specific power as high as 800 W/kg.

Several vendors

Solar Panels

Why not buy a nice full-sized panel and see what we can collect with it?

330W for $271 ($.78/W)

100W for $115 ($1.15/W) (bought)

Panels and battery setup

  • Tesla powerwall + solar real-world results:
    • SC325 panels (325W) x 18 panels; peak output 5850W; actual ~5000W; 200A panel 100A subpanel for powerwall circuit (100A to AC (separate?)); 14kW storage 5kW continous 7kW peak; 89% efficiency; -29 to 50C range; 1oyr warranty; 122kg (powerwall)
    • summer 32.2kWH on a hot day; fall 25.6kWH on sunny day; winter 22.7kWH
    • summer with ac, 50.3 kWH drawn - 21.6kWH from grid, had spikes above powerwall ability
    • cloudy and hot 29kwh (grid) + 1.8kwh (powerwall) it started low after many hot days
    • fall rainy day (5.1kwh from solar(22kwh on sunny day), used 18kwh)
    • cool and sunny october credit of $25
    • $170 avg monthly savings, system will pay for itself in 11 years
  • Someone used the Renogy panel to charge their RV, "My system consists of the following main components:"
2 - Victron Multiplus 12/3000/120-50
Victron Blue Solar charge controller MPPT 150/85
15 - 100 watt Renogy solar panels
Victron Color control gx
Victron BMV-702 battery monitor
4 - 1000Ah LifePO4 Winston battery cells

Super capacitors

  • Super-capacitors are not ready to outperform batteries, at least not yet.
    • Because existing supercapacitors have poor energy density per kilogramme (currently around one twentieth of existing battery technology), they have been unable to compete with conventional battery energy storage.
    • Even with this restriction, supercapacitor buses are already being used in China, but the current technology means that they need to stop to be recharged frequently (i.e. at almost every bus-stop). - this is NOT A PROBLEM, as our capacitors would be CONTINUOUSLY CHARGING. As long as we could deliver often, super capacitors may have use - we will have to wait until we know both the orbits and the delivery points.
  • Demonstration of using a supercapacitor to meet the needs of charging a car, definitely within its ability. Electroboom agrees.

Long-range handshake

  • Link budget used to identify losses in any telecommunications system
  • Here is how NASA did it with Voyager (1970-2029!)

Small Lab Research

We should be able to set up two arduinos or pis, one receiving sun solar to power a laser, and another receiving laser solar to power a battery. We have a lot to learn about basic electrical wiring and arduinos and pis.

A hackster laser morse code transmitter and receiver setup, very useful The laser that was used, very popular, didn't find any others yet

There are lots of competing low-quality solar+battery projects, where's the winner? Still looking...

General IoT research

Strong lasers:

Other random stuff:

Launching Payloads to Space

Rocket Lab’s Electron booster launches small satellites commercially - launch about 300 pounds of payload for $5 million

Nasa "Venture Class" contractors circa 2015

Smallest Orbital Rocket The SS-520 No. 5 three-stage sounding rocket launched TRICOM-1R microsatellite from the Uchinoura Space Center, in Kagoshima, Japan, on 3 February 2018. TRICOM-1R weights approximately 3 kg. The "payload of up to 140kg" is the information for this rocket when it is used as a two stage sounding rocket. Then it does take 140 kg to a suborbital flight with a maximum altitude of 800 km (at which point it will have zero velocity). Here, the place of this payload is taken by the third stage. Plus, there is extra hardware between the first and the second stage. The satellite that rides on the third stage and is placed in orbit is just 3 kg, and that's roughly what this rocket's maximum payload to orbit is (not counting the weight of the spent third stage itself, which ends up in the same orbit.)

This comes to well over a million dollars per kilogram of useful payload into orbit. But it is still the tiniest space booster! And if your goal is to put something into a specific orbit in the cheapest way, rather than to put tons of stuff in the cheapest way per kg, a few million dollars is a reasonably low price -- comparing to any available today alternative. (There are several start-ups trying to build very small and very low cost boosters)

Today, most builders of nano-satellites use ride-share services and get their 3-6 kg satellites launched for under half a million dollars each, together with dozens or hundreds of others in the same launch. The most popular ride-share service is offered by the operators of the PSLV rocket in India. Startups and universities from dozens of countries use it every year to get their cube-sats into orbit.

General Notes

Question: what's the maximum input into a photovoltaic cell? Exposing it to the sun in space will provide what percentage of peak opportunity? Should we employ mirrors or prisms to redirect more sunlight into the PV cells? what would be most cost effective: adding more PV cells or adding redirected/reflected sunlight to existing PV cells?

Wikipedia: Wireless_power_transfer via laser (aka "Power Beaming")

Wikipedia: Space Based Solar Power (SBSP)

Long Range Wireless Power by Wi-Charge demoed at CES 2018 - First wireless power system using lasers for consumer applications. Complies with mandatory IEC 60825 sagfety standards for consumer use.

OEM looking to incorporate wireless power modules into new products? Apply for beta

NASA Armstrong Fact Sheet: Beamed Laser Power for UAVs

Power by Light - blog with working prototypes

Youtube: Wirelessly Powered Train

Youtube: Photovoltaic laser power converters with increased voltage output (27m)

Academic Papers

U.S. Energy Department’s own Lawrence Livermore National Laboratory (LLNL) 2009 proposal (PDF) with Infographic

laser power beaming light-to-electricity conversion efficiency correlates directly between electricity conversion and heat generation - abstract behind paywall

Development and characterisation of laser powerconverters for optical power transfer applications - French paper 2013

Paper: Design and optimization of GaAs photovoltaic converter for laser power beaming

Paper: Photovoltaic laser power converters for wireless optical power supply of sensor systems

Paper: High-Voltage GaAs Photovoltaic Laser Power Converters

Youtube infotainment

  • electronics: jehugarcia, ElectroBOOM, GreatScott!, EEVBlog, bigclivedotcom, Jeremy Fielding, Fran Blanche, The Hacksmith
  • lasers: styropyro, Marco Reps
  • robotics: Metatronics, Adafruit Industries, simone Giertz (relentlessly pursues creativity with fun robots)
  • other: Captain Disillusion (awesome entertaining video 3D graphics), Cody'sLab (chemistry), AvE (mechanical engineering (and electronics?)), PhysicsGirl (physics)
  • general: The King of Random, TheBackyardScientist, SmarterEveryDay, Veritasium, Vsauce, Adam Savage’s Tested