Retail Beamed Power for a Micro Renewable Energy Architecture: Survey
Opportunities In Power Beaming For Micro Renewable
NarayananEnergy
Komerath
Professor, Daniel Guggenheim School
of Aerospace Engineering
Georgia Institute of Technology
Atlanta, Georgia USA
Concept development work was supported by NASA under the
EXTROVERT cross-disciplinary innovation initiative. Mr. Tony Springer
is the Technical Monitor.
Experimental Aerodynamics and Concepts Group
Summary
•Breakthroughs in renewable energy require cross-disciplinary innovation.
•Developing advanced concepts that go well beyond today’s practices, is a
useful way for students to learn about innovation across discipline barriers.
•Issue: How to develop a power transmission and distribution architecture
based on wireless beaming.
•Processes of defining requirements and selecting parameters.
•Education through cross-disciplinary learning on projects. Student
experience over the years starting from initial concept exploration to present.
•Idea of “concept resilience” as it applies to students and faculty developing
advanced concepts.
Experimental Aerodynamics and Concepts Group
Introduction
•Renewable energy: constraints and innovations come from a very broad
range of disciplines within and outside science and engineering.
•Paper is about how learners from traditional disciplines deal with grand
challenges and opportunities to innovate towards far-off goals, learning what
they must learn, wherever that knowledge can be found, and surviving the
continuous onslaught of superstitions without losing sight of reality.
“Learning is not just through courses”.
Experimental Aerodynamics and Concepts Group
Why study power beaming
•Concept: electric power delivery to customer sites through narrow beams of
electromagnetic waves,
•Essential component in Space and atmospheric Power Grid.
•Enables solar or wind power plants to be built at remote sites.
•Reduces amount of auxiliary generation capacity required to meet
“baseload supplier” criterion.
•Power delivery to islands and mountainous sites using towers, mountain
ridges or lighter-than-air platforms.
•Retail scale, power delivery to rural homes and villages, and allows micro
power generation systems to become viable.
•At a very small scale, power beaming provides essential services to people
who have no other access to electric power other than portable batteries or
fossil-powered generators.
•Massive significance for rural electrification and renewable power
generation.
Experimental Aerodynamics and Concepts Group
Aerospace Interest: 3-stage Approach to Power Delivery
Tower to village (KW-1MW per tower )
2. Regional plant or Space – stratospheric platform – customer (10-100MW per platform)
3. Space Power Grid – national /global needs (100MW per satellite)
Beamed delivery to remote sites and islands is possible from Space / Stratospheric Platforms/ UAVs
Retail beaming can close the business case for beamed power, while enabling many communities to
leap ahead of terrestrial power grid expansion
Surface range to visible horizon, km
1.
500
450
400
350
300
250
200
150
100
50
0

global
Local
0
Regional
10
20
RelayAerodynamics
height AGL,
km Group
Experimental
and Concepts
30
Baseline economic model for rural BPTS
• Wired or Strat-form power delivery to rural station
• Beamed “last kilometer” to customer antenna
• Synergy with mobile phone and railway infrastructure where possible
• Local industry/major users must subsidize costs of reaching small
users
Experimental Aerodynamics and Concepts Group
Potential Near-Term Applications








Broad area low intensity power
distribution for emergencies
Deliver to local village grid
Remote military or scientific outposts
High endurance miniature robots
Distributed micro power generation
Remote area exploration
Increased range for electric vehicles
Rapid restructuring of grid topology for
damage mitigation
Experimental Aerodynamics and Concepts Group
Central Issue of this paper
•How does one go about developing such an idea?
•How will students learn the basic issues, concepts, theory and skills
required to develop the concept?
Experimental Aerodynamics and Concepts Group
Learning Issue #1: Concept Resilience
“surviving the continuous onslaught of superstitions without losing sight of
reality.”
To understand the issues in power beaming, enough to consider
developing viable solutions, the learner must surmount a daunting
array of obstacles.
Usual Conclusion: Need a cross-disciplinary team of specialists,
which is an expensive proposition, to be deferred until a major project
is funded.
Corollary: No such project can be contemplated until concept
development has shown that there is a feasible path in the near term,
and only the detailed design remains to be developed, with all
required technological solutions well established and available.
Experimental Aerodynamics and Concepts Group
Issues and discipline areas involved in power beaming
Experimental Aerodynamics and Concepts Group
Other Learning issues:
•Initial concept exploration
•Identifying the required and achievable bounds on efficiency
•Minimum power transaction level for system breakeven
•Argument for millimeter wave beaming
•Finding sources and strengthening cost estimation
•Satellite orbits and propagation loss refinement
•Course development and iterative refinement of knowledge
•Retail power beaming
•Formalizing resources for knowledge establishment and transfer
Experimental Aerodynamics and Concepts Group
Summary: Learning opportunities in power beaming
Experimental Aerodynamics and Concepts Group
1. Expense of solid state arrays vs. PV arrays
Issues and solutions
Issue
Solution/Argument
Low efficiency of generation and
transmission.
Compare value of 1st watt-hour
Opportunity cost of waiting for grid
Expense of solid state arrays vs. PV
arrays
Design for synergy. PV panels as mm
wave antennae at night. Integrated
PV/mmwave chips toreceive,
convert and transmit power
Atmospheric Propagation Losses
Minimize horizontal path at low altitude.
Use burn-through or Evaporation Ducts
High Beam Intensity
Automatic cutoff unless link is functioning
Health Effects of Millimeter Waves
Unknown – needs research
Generation of Millimeter Waves
Mass-produced solid-state arrays;
Photonic approaches
Infrastructure
Mobile Telephone Infrastructure as
convenient “last kilometer” transmitters
Experimental Aerodynamics and Concepts Group
Conclusions
•Power beaming enables breakthroughs in renewable power architectures,
both on earth and in Space.
•Beamed power can reach islands, remote communities, and hundreds of
millions of people in less developed nations, giving them access to many
essential services and to global connectivity.
•Study of power beaming opens several leading edge opportunities.
•Concept development helps student realize how advances fit in with each
other, and allow progress towards larger goals.
•Successfully involves students at all levels and from various disciplines.
• Developers must first develop “Concept Resilience”.
•Typical learning methods of students include discussions with other students
and faculty, as well as internet search techniques, and reading textbooks.
Experimental Aerodynamics and Concepts Group
Receiver Diameter, m
Antenna Size Dictates Millimeter Wave Regime
(GEO receiver size is off the chart)
50
50m antenna, 30km Strat
40
Platform
10m Ship/UAV antenna,
30
20km
20
10
0
0
100
Frequency, GHz
200
•Frequencies below 100GHz are not viable for delivery from Space, due to costs of space and
ground infrastructure. Hence interest in millimeter waves.
•Mmwave infrastructure is suitable for retail family / village sized receivers
Experimental Aerodynamics and Concepts Group
Regional power plant to stratospheric platform (Stratoform) to customer site
•Range to 600 km
•Power level ~10 to 100 MW
•Multiple receivers
•“Burnthrough” beam to handle bad
weather
http://images.gizmag.com/
hero/6358_20100630239.jp
g
http://images.gizmag.com/
hero/6358_20100630239.jp
g
Experimental Aerodynamics and Concepts Group
http://www2.nict.go.jp/q/q262/3107/end1
01/ENG/FAQ/FAQ-E1.htm
Dealing With Low Efficiency
•Value of first watt-hour
•Opportunity cost of waiting for wired grid
Experimental Aerodynamics and Concepts Group
Many needs are met by a few watt-hours
TABLE 1. User Requirements for Micro Renewable Energy Systems
Use
Lighting1
Fan2
Communications3
Computers4
TV5
Wireless Router6
Refrigerator7
Total Electric
Cooking8
Water Heating9
Air Heat or A/C10
Total Heat Energy
Total Energy
1
2
3
4
5
6
7
8
9
10
Cold-Region
KW rating
0.020
0.034
0.004
0.113
0.100
0.007
0.400
0.678
1.000
1.000
1.350
3.350
4.028
Cold-region
KWh per day
0.200
0.407
0.012
0.452
0.400
0.007
6.800
8.278
2.000
2.000
10.801
14.801
23.079
Warm-region
KW rating
0.020
0.034
0.004
0.113
0.100
0.056
0.400
0.727
1.000
1.000
1.900
2.713
3.440
LEDs equivalent to 200watts of incandescent lamps
Lasko vertical fan, 120vAC, 0.4A
Cellphone charger, Samsung 2004 model
Sony VAIO 17 inch-display laptop charger, 2010 model
LCD/LED Flat panel TV average, 2010.
2010 Average
18 cu. ft. US average, 2010
Electric cooktops, 2010
Electric showerhead heater takes 2.75KW, 2.5GPM flow
Cold regions use AC 3 months, warm regions 6 months, but have natural ventilation. Only
cold regions use heat.
Experimental Aerodynamics and Concepts Group
Warm-region
KWh per day
0.120
0.407
0.012
0.452
0.400
0.056
9.600
11.048
2.000
1.000
4.275
4.603
15.651
Dry Atmospheric Absorption for Vertical Transit
Good windows at ~100, 140, 220GHz
Need: Narrow-band data
to identify best windows
near 100 GHz and 220GHz
Experimental Aerodynamics and Concepts Group
Atmospheric Absorption for Horizontal Propagation (Why go up instead)
Line A: Average absorption at sea level, 20C, 1atm, H2O vapor 7.5 g/m3)
Line B: Altitude 4 kilometers pressure altitude, (0C, Water Vapor Density= 1 g/m3)
http://ops.fhwa.dot.gov/publications/viirpt/sec5.htm
Experimental Aerodynamics and Concepts Group
Impact of rain and fog: Need “burn-through”.
220GHz
94GHz
DSP/solid state generation
permits use of an initial
burn-through frequency
followed by main power
beam
Experimental Aerodynamics and Concepts Group
Technology Opportunities
•
•
•
•
•
•
•
•
•
•
•
Integrate mm-wave receivers with solar panels
Narrow-band phase-array receivers for laser and mm-waves, integrated with PV panels
Nanotube broadband direct solar conversion antenna
Burn-through rain, clouds and fog using mmwave and other wavelengths
Lightning analogy: Create conductive path for mm-wave beam using “seed” beam
Use waste heat on relay platforms to generate burn-through beam
Co-use communications and power transfer control equipment
Improve conversion efficiency to & from 200-220 GHz
Satellite waveguides
Thermal management
Effects of scattered 220Ghz radiation on humans/animals
Experimental Aerodynamics and Concepts Group
Conclusions
1. Rising demand for connectivity and personal electronics, creates an opportunity to leap-frog
grid expansion using retail power beaming.
2. Millimeter wave beaming brings antenna sizes practical for retail installation.
3. Enables retail power distribution to off-grid locations and islands.
4. Closes the business case for distribution through Space and statospheric platforms.
5. Enables synergy with distributed micro renewable power architectures.
6. Value of first few watts and watt-hours >> marginal cost of utility power.
7. Synergy with photovoltaic arrays multiplies cost-effectiveness of micro power architectures
8. Optimal frequencies for moist atmospheres differ from those for long-distance dry air and
vacuum beaming.
9. Solid-state arrays enable several beam frequencies from the same arrays in order to serve
multiple purposes.
10. Indian village electrification offers an opportunity to establish a retail beaming infrastructure.
Rural economics model works best with stratospheric platforms, local beamed delivery and
subsidized cost to small users.
11. High-resolution data needed for 100GHz and 220GHz bands
12. Low efficiency and weather issues are not show-stoppers for retail millimeter wave power
beaming.
Experimental Aerodynamics and Concepts Group
Beamed Retail Power Transmission/ Distribution System
•Wireless transmission of power (not just signals with information) over relatively short
distances to multiple end-user receivers.
•Usually implies focused point-to-point transmission with highly directional antennae, and
provisions for energy storage at either end.
•Conventional solutions using <10GHz microwave, and some proposed solutions using lasers.
•Our interest is in the millimeter wave regime, specifically near 220 GHz
DC to mm
wave
conversion
Beam Formation
Transmission &
Reception
mm wave
to DC
conversion
Experimental Aerodynamics and Concepts Group
Space Power Grid Concept:
220 GHz
140GHz Propellant Heating Beam Being Considered
by NASA/USAF
Experimental Aerodynamics and Concepts Group
3. Space Power Grid

Use space-based infrastructure to
boost terrestrial “green” energy
production from land and sea:
argument for public support.

Full Space Solar Power (very
large collectors in high orbit) will
add gradually to revenuegenerating infrastructure.
Exploit large geographical, daily and
seasonal fluctuations in power cost (Landis
2004, Bekey 1995).
Beam to other satellites
Retail delivery (SPS2000).
Space Power Grid: Redistributing Energy
Technical risks in dynamic
beaming/reception/ transaction
system.
Inefficient conversion to and
from microwave vs. terrestrial
high-voltage transmission lines.
FIGURE 1. Space Power Grid Satellite Receving And Redistributing Beamed Power.
Team: Brendan Dessanti, Janek Witharana
Experimental Aerodynamics and Concepts Group
Power delivery to points of local distribution
•Low-altitude horizontal beaming is inefficient unless burn-through techniques are perfected.
•Use vertical beaming to and from high-altitude platforms wherever possible.
Experimental Aerodynamics and Concepts Group
The Dream of Energy Independence
•Terrestrial solar, wind and biomass power plants
•Space-delivered solar power
•Beamed power to complement local generation, in off-grid communities
•Hydrogen generation using excess / spike power
•Stored hydrogen and bio-gas for fuel cells and transportation
Experimental Aerodynamics and Concepts Group
Burn-through rain, clouds and fog using mmwave and other
wavelengths
Solid state arrays / DSP-PLL generation approach allows consideration of tuning to narrow bands,
and shifting to a pilot beam for a short duration to
prepare the path for the main beam
Options to investigate:
1.Find narrow lines in 220GHz window, where propagation efficiency is higher.
2.Saturate? No experiments found so far on the effect of sustained beam energy addition on wet air
for durations of minutes
2. Deliberately heat using selected frequencies and create low-density path?
3.Lightning analogy? Create conductive path for mm-wave beam using “seed” beam
Experimental Aerodynamics and Concepts Group
Demand for mobile connectivity and other electric devices far
outpaces power grid expansion.
•India: 638,000 villages, 80 percent have at least one electric line.
•415 million people have no access to electricity
•Over 450 million mobile phone accounts (Multiple accounts per user).
•Retail Power Beaming is a viable alternative to constructing wired grids for several future
applications, despite low efficiency.
•Route for the small electronic devices market to leapfrog the centralized power grid, in
many parts of the world.
Experimental Aerodynamics and Concepts Group
Summary Observations -2
•Direct conversion from broad-band solar to beamed mmwave appears feasible.
•Integrated antenna / PV generators already in use
•Large-scale arrays of solid-state devices with DSP and PLL to generate mmwave
•Laser efficiencies may be on cusp of breakthrough but need changes in laws/treaties
Most current “systems analyses” of SSP prospects appear to assume <$400/lb launch costs
to LEO. This is not realistic. Must insist on disciplined costing to see the real technology
opportunities.
Experimental Aerodynamics and Concepts Group
The Space Power Grid Approach
Use space-based infrastructure to
boost terrestrial “green”
energy production from land
and sea: argument for public
support.
Full Space Solar Power (very
large collectors in high orbit)
will add gradually to revenuegenerating infrastructure.
•Exploit large geographical,
daily and seasonal fluctuations
in power cost.
•Beam to other satellites.
•Retail delivery (SPS2000).
Experimental Aerodynamics and Concepts Group
Acknowledgement
Support from NASA under the “EXTROVERT” cross-disciplinary learning
initiative is gratefully acknowledged.
Experimental Aerodynamics and Concepts Group
Space Solar Power the old way
GEO: S=36000km
MEO: ~10000km
http://www.newscientist.com/data/images/archive/2631/26311601.jpg
LEO: ~400km
Earth
Radius ~6370km
Experimental Aerodynamics and Concepts Group
Afternoon Sun system.
•80 minutes of access per 24 hours per location.
•This orbit performs 23 revolutions around the earth every 48 hours.
Ground Tracks of 6 sun-synchronous satellites at 1900 km
Experimental Aerodynamics and Concepts Group
Absorption vs. Spillover
Most GEO/ 5.8GHz architectures assume receivers sized for 83% beam capture
because of the large receiver size
Example:
5.8GHz: 84% Beam capture, 95% Transmission through atmosphere
Net capture = 0.95*0.84 = 80%
220GHz: 99% Beam capture, 90% transmission = 89%
Benefits of compact antenna are far beyond this.
Both laser and mmwave enable compact, 99% capture receivers.
Experimental Aerodynamics and Concepts Group
Nanotube broadband direct solar conversion antenna, with
narrow-band high-efficiency receivers for mm wave.
http://www.aip.org/png/2004/221.htm
Antenna for Visible Light
“Shown: An array of aligned, but randomly placed, carbon
nanotubes which can act like a radio antenna for detecting light at
visible wavelengths. The scale bar is one micron in length.
Wang et al., Applied
Physics
Letters,
27 September
2004.”
Experimental
Aerodynamics
and Concepts
Group