Over the Horizon Wireless Power
Transmission (OTH-WPT)
A Low Cost Precursor for Space Solar Power
Stephen Blank, IBE Systems & NYIT
Paul Jaffe, NRL
Overview
• Background
– Laser SSP Concepts
– Laser Power Beaming Demonstrations
– SSP Concepts with High-Altitude Elements
• Proposed Terrestrial Demonstration
– Configurations
– Challenges
Selected Laser SSP Concepts
JAXA Concept, circa 2011
EADS Astrium Concept, circa 2010
Aerospace Corp. Laser Concept, circa 2002
Selected Laser Power Beaming
Demonstrations
EADS Astrium tracking laser to power rover, circa 2003
Kinki Univ. & Hamamatsu Photonics Inc. laser power to
small helicopter, circa 2007
Lasermotive outdoor laser power to UAV, circa 2012
Comparison of Microwave and Laser
Power Transmission for SSP from GEO
Microwave
Laser
Transmit frequency
5.8 GHz
1.4 mm
Transmit Aperture Diameter In GEO
1 km
2.5 m
Receiving Aperture Diameter On or
Near Earth
3.2 km on earth
40 m
Demonstrated Transmitter
Conversion Efficiency
~80%
~30%
Demonstrated Receiver Conversion
Efficiency
~90%
~50%
Vulnerability to Weather
Probably negligible
Not negligible*
Spectrum Allocation Challenges
Likely to be high
?
International Political Challenges
?
Likely to be high*
*this problem may be reduced or eliminated by using a high altitude receiving platform
Selected High Altitude Receiving
Platform SSP Concepts
C.A. Schafer, D. Gray, "Transmission media appropriate lasermicrowave solar power satellite system", Acta Astronautica
79 (2012) 140–156
S. Blank, S. Leete, P. Jaffe, “Feasibility Study of Space Based
Solar Power to Tethered Aerostat Systems”, IEEE Aerospace
Conf 2013
Space to Tethered Aerostat SSP
• Beaming from space to a high altitude tethered
aerostat avoids main effects of atmospheric
attenuation
• Potentially allows use of “eye-safe” laser transmit
frequency which results in far smaller apertures vs.
microwave for: transmit antenna in GEO and receive
aperture on the aerostat
Demonstration Motivation
• The high cost of getting to space has been an
obstacle to demonstration implementations
• Over the Horizon Wireless Power Transmission, OTHWPT, is proposed as a low cost precursor to SSP that
does not require access to space
“...large-scale demonstration of power beaming is a
necessary step to the development
of solar power satellites.”
– Geoffrey Landis, scientist and author
Demonstration Configuration
Demonstration Configuration
Functional Block Diagram
Laser Power Converter
Panel
Aerostat or
Airborne
Platform
Trihedral
Reflector Panel
Pilot Signal
Detector
Power
Supply
Tether
Beam
Path
Control
Electronics
Laser
Ground Location 1
Steering
Mirror
Power
Conditioning
& Distribution
Ground Location 2
Demonstration Configuration Range
Range as a function of air platform height (km)
300
r ( h) 200
100
0
2
4
6
h
8
10
Demonstration
Configuration
• Advantages:
• Atmospheric attenuation one
direction only
•Power easily sent to multiple
locations
• Disadvantages:
• Requires tether
• Potential radiation hazard
Converter
Panels
Power
Down
Tether
Notes:
Airship altitudes above
troposphere
Transmitter
Airborne Reflector Configuration
• Disadvantages:
• Atmospheric attenuation both directions
• Potential radiation hazard
• Advantages:
• One airship
• No tethers
Reflector
Note:
Tether could be used with
airship if desired.
Transmitter
Converter
Panels
Power Beam Down Configuration
• Advantages:
• Atmospheric attenuation one
direction only
• Power easily sent to multiple
locations
• Easier logistics at receiving site
• Disadvantages:
• Requires tether
• Potential radiation hazard
Transmitter
Power
Up
Tether
Converter
Panels
Beam at Altitude Configuration
• Advantages:
• Minimizes atmospheric attenuation
• Very long range, potentially > 1000 km
• Power easily sent to multiple locations
Converter
Panels
Power
Down
Tether
Notes:
Airship altitudes above
troposphere
• Disadvantages:
• Two airships
• Requires tethers
Transmitter
Power
Up
Tether
Design Challenges
•
•
•
•
•
•
•
•
•
Airborne/field deployable high power lasers
Beam pointing, tracking, retro-directivity
Compensating for atmospheric effects
Mirrors for high power lasers
Laser power conversion
Laser radiation safety
Air platform: high altitude, long duration*
Tether: light weight, low resistance, high voltage
Air traffic control
* Aerostats currently operate at 4-5 km with up to 90
mph wind survivability.
Hardware Sources
•
High power lasers:
– IPG Photonics
– Teradiode
•
Beam Control:
– Adaptive Optics / Northrop Grumman
– Boeing
– Lasermotive
– Lighthouse Development
•
Aerostats:
– ILC Dover
– T-com
•
Laser energy conversion:
– Spectrolab
– JX Crystals
OTH-WPT Goal & Conclusion
• Provide deployable, portable, long range,
economical power transmission for security,
commercial, and civil applications
• Over the Horizon Wireless Power Transmission
represents an achievable, low-cost precursor
for Space Solar Power
Thank You
• Stephen Blank, PhD, IBE Systems Corp. and
New York Institute of Technology,
[email protected] , [email protected]
• Paul Jaffe, NRL, [email protected]
Backup
Aerostats
Lighter
Than High
AirAltitude
(LTA)
Heavy Lift
Airships
ABC A60
56K
ISIS
4.2M TowTech
PTDS 74K
HALE-D
SkyTug
Zeppelin
TARS 420K
MA-3
HAA
StarTower
LEMV
Lightship
GNSS 40K to 80K
ILC Dover Proprietary Information
Technical Issues
• The amount of loss along the tether during
the transmission of the electrical power to
the ground is an important technical issue.
• This loss can be reduced through the use of a
low resistivity conductor and the choice of a
high voltage for transmission.
Technical Issues
• Clouds can occur at operational altitudes.
• Statistical analysis of meteorological data show that
the probability of occurrence decreases with
altitude and is not statically significant at altitudes
above 6 km.
• ref: i) Chilbolton Observatory, UK
ii) Cloudnet, 2007, http://www.cloud-net.org/
What is Proposed?
• Long Range Wireless Power Beaming using a
ground-based high-power laser and a highaltitude receiving platform
• 100s of km range
• Delivery of 100s of kW electric power
• Many other configurations are possible to
meet variety of range, power, weather and
tactical needs
Tethered Aerostats
widely used, mfg. in the U.S.
Tethered Aerostat with ground station
Tether properties
Aerostats, widely used, U.S. mfg. items.
Demonstration Configuration
• Advantages:
• Atmospheric attenuation one
direction only
•Power easily sent to multiple
locations
• Disadvantages:
• Requires tether
• Potential radiation hazard
Notes:
Airship altitudes above
troposphere
Transmitter
Converter
Panels
Power
Down
Tether
Radiation Safety
•
•
•
•
Interlocking intrusion control
Beam pointing positive control
Power density limitations
Wavelength choice to minimize potential
radiation hazard to personnel, animals and
equipment, (1.5 mm, eye-safe)