experimental aerodynamics and concepts group retail beamed power for a micro renewable energy...

Experimental Aerodynamics and Concepts Group

Retail Beamed Power for a Micro Renewable Energy Architecture: Survey

Retail Beamed Power for a Micro Renewable Energy Architecture: Survey

Narayanan Menon Komerath

Professor, Daniel Guggenheim School of Aerospace Engineering

Georgia Institute of TechnologyAtlanta, Georgia USA


•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.

Demand for mobile connectivity and other electric devices far outpaces power grid expansion.


Aerospace Interest: 3-stage Approach to Power DeliveryAerospace Interest: 3-stage Approach to Power Delivery1. 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/ UAVsRetail beaming can close the business case for beamed power, while enabling many communities to leap ahead of terrestrial power grid

expansion

Relay height AGL, km

Regional

global

Surf

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rang

e to

vis

ible

hor

izon

, km

Local


Antenna Size Dictates Millimeter Wave RegimeAntenna Size Dictates Millimeter Wave Regime(GEO receiver size is off the chart)(GEO receiver size is off the chart)

Frequency, GHz

Rec

eive

r Dia

met

er, m

•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


http://images.gizmag.com/hero/6358_20100630239.jpg

http://www2.nict.go.jp/q/q262/3107/end101/ENG/FAQ/FAQ-E1.htm

http://images.gizmag.com/hero/6358_20100630239.jpg

Regional power plant to stratospheric platform (Stratoform) to customer siteRegional 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


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-hourOpportunity 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


Dealing With Low Efficiency•Value of first watt-hour

•Opportunity cost of waiting for wired grid


TABLE 1. User Requirements for Micro Renewable Energy Systems

Use Cold-Region KW rating

Cold-region KWh per day

Warm-region KW rating

Warm-region KWh per day

Lighting1 0.020 0.200 0.020 0.120 Fan2 0.034 0.407 0.034 0.407

Communications3 0.004 0.012 0.004 0.012 Computers4 0.113 0.452 0.113 0.452

TV5 0.100 0.400 0.100 0.400 Wireless Router6 0.007 0.007 0.056 0.056

Refrigerator7 0.400 6.800 0.400 9.600 Total Electric 0.678 8.278 0.727 11.048

Cooking8 1.000 2.000 1.000 2.000 Water Heating9 1.000 2.000 1.000 1.000

Air Heat or A/C10 1.350 10.801 1.900 4.275 Total Heat Energy 3.350 14.801 2.713 4.603

Total Energy 4.028 23.079 3.440 15.651 1 LEDs equivalent to 200watts of incandescent lamps 2 Lasko vertical fan, 120vAC, 0.4A 3 Cellphone charger, Samsung 2004 model 4 Sony VAIO 17 inch-display laptop charger, 2010 model 5 LCD/LED Flat panel TV average, 2010. 6 2010 Average 7 18 cu. ft. US average, 2010 8 Electric cooktops, 2010 9 Electric showerhead heater takes 2.75KW, 2.5GPM flow 10 Cold regions use AC 3 months, warm regions 6 months, but have natural ventilation. Only

cold regions use heat.

Many needs are met by a few watt-hours


Baseline economic model for rural BPTS

• Wired or Stat-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


Potential Near-Term ApplicationsPotential 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


Dry Atmospheric Absorption for Vertical Transit

Good windows at ~100, 140, 220GHz

Need: Narrow-band datato identify best windowsnear 100 GHz and 220GHz


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)

Atmospheric Absorption for Horizontal Propagation (Why go up instead)

http://ops.fhwa.dot.gov/publications/viirpt/sec5.htm


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


Technology OpportunitiesTechnology 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


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 architectures8. 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 bands12. Low efficiency and weather issues are not show-stoppers for retail millimeter wave power

beaming.

Conclusions


AcknowledgementAcknowledgement

Support from NASA under the “EXTROVERT” cross-disciplinary learninginitiative is gratefully acknowledged.


Beamed Retail Power Transmission/ Distribution SystemBeamed Retail Power Transmission/ Distribution System

mm wave to DC

conversion

mm wave to DC

conversion

DC to mm wave

conversion

DC to mm wave

conversion

Beam Formation Transmission &

Reception

•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


140GHz Propellant Heating Beam Being Considered by NASA/USAF

Space Power Grid Concept:220 GHz


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 revenue-generating infrastructure.

Exploit large geographical, daily and seasonal fluctuations in power cost (Landis 2004, Bekey 1995).Beam to other satellitesRetail delivery (SPS2000).

Technical risks in dynamic beaming/reception/ transaction system.

Inefficient conversion to and from microwave vs. terrestrial high-voltage transmission lines.

Space Power Grid: Redistributing EnergySpace Power Grid: Redistributing Energy

FIGURE 1. Space Power Grid Satellite Receving And Redistributing Beamed Power.

Team: Brendan Dessanti, Janek Witharana


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.


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


Burn-through rain, clouds and fog using mmwave and other Burn-through rain, clouds and fog using mmwave and other wavelengthswavelengths

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 minutes2. Deliberately heat using selected frequencies and create low-density path?3.Lightning analogy? Create conductive path for mm-wave beam using “seed” beam

Solid state arrays / DSP-PLL generation approach allows consideration of tuning to narrow bands, and shifting to a pilot beam for a short duration toprepare the path for the main beam


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 coststo LEO. This is not realistic. Must insist on disciplined costing to see the real technology opportunities.


The Space Power Grid Approach

•Exploit large geographical, daily and seasonal fluctuations in power cost.•Beam to other satellites.•Retail delivery (SPS2000).

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 revenue-generating infrastructure.


http://www.newscientist.com/data/images/archive/2631/26311601.jpg

Space Solar Power the old way

GEO: S=36000km

LEO: ~400km

MEO: ~10000km

Earth Radius ~6370km


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


Absorption vs. Spillover

Most GEO/ 5.8GHz architectures assume receivers sized for 83% beam capturebecause of the large receiver size

Example:

5.8GHz: 84% Beam capture, 95% Transmission through atmosphereNet 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.


“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.”

Antenna for Visible Light

Nanotube broadband direct solar conversion antenna, with narrow-band high-efficiency receivers for mm wave.

http://www.aip.org/png/2004/221.htm

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