Testbeds Connecting Space Technology To
Terrestrial Renewable Energy
Narayanan Komerath
Professor, Daniel Guggenheim School of Aerospace Engineering,
Georgia Institute of Technology, Atlanta
komerath@gatech.edu
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
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Thrust of the Paper: How to Learn In a New Cross-Disciplinary Area
1. Fertile area of R&D at interface between space and terrestrial micro
renewable energy.
2. End-to-end efficiencies are small, even with space systems.
3. Innovation focus on sustainable alternatives for high Figure of Merit.
4. Steep cross-disciplinary learning curve.
5. Approach based on courses, testbeds, knowledge base development,
learning resources, individual and team projects.
6. Testbeds approach enables hands-on experience, test cases for
simulation, and enables continued advances to provide greater
functionality for the same footprint.
7. Organizing testbed developments poses tradeoffs between timeliness,
depth and breadth.
8. Evolved method of organizing and assessing student team activity is
summarized.
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Fertile area of R&D at interface between space and the terrestrial micro renewable energy.
Space ISRU research
Terrific R&D!
NO MARKET!!!!
•ISRU customer is the
government.
•Devices represent the
best of human technology.
MICRO RENEWABLE ENERGY SYSTEMS
Terrestrial Micro Renewable Power
Global Market
NO R&D!!!!
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Requirements for terrestrial micro energy systems
•Stand-alone (off-grid) energy systems located in close proximity to users.
•Local environmental constraints on noise, smell, toxic waste, and aesthetic offence.
•Capital, operational cash flow, cost of money, opportunity cost and ROI are financial constraints.
• Constraints include humanpower, expertise, roads, utilities including water, telecommunications,
and competition or conflict with other resources and approaches.
•Requirement is 1 to 3 kW rated power, providing enough storage to deliver up to 24 kWh per day.
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
2. Efficiency is small even for Space power systems!
Issue is to achieve high Figure of Merit (but not above 1!!!!)
1. Low thermodynamic efficiency of heat engines with small temperature gradients
2. Large surface area per unit mass, resulting in high friction and heat transfer losses.
3. Highly fluctuating power
4. High fixed costs of power control and transmission subsystems per unit power transacted.
5. Generally high mass per unit power.
6. Need for energy storage
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
3. Innovation focus on sustainable alternatives that achieve high utility.
Space Technology
High intensity solar cell
Optical waveguides to convey solar power directly use point
Terrestrial Testbed Incorporation
3KW Hybrid solar PV/thermal generator
Reduce PV area on home systems. Add to solar water heater.
High temperatures electrolysis.
Combine with PV arrays.
Photocatalytic water purifiers convert organic impurities to CO2. Integrate into solar water heaters. Ion/ UV water purifiers
Solid oxide fuel cells chemically extract H2 from hc fuels
5kWhe/day fuel cells combine furnace, water heater, generator
Thermoelectric (TE) power; Nanostructured TE generators.
Portable TE refrigerators powered by vehicle batteries.
High temp thermo PV. Theoretical 85% narrowband conversion. Tungsten photonic crystals extract power from cooking flames.
Converting sunlight to microwaves using PV
Crop drying in unseasonal rain.
Solar Rankine Cycle: spacecraft thermal management systems
Rooftop solar thermal using supercritical CO2 at 70 atm.
Stirling engines, with DT ~ 6 C. Various fuels & heat sources.
Thermo acoustic cooker-refrigerator
Atmospheric water generation
Solar vapor-condenser refrigerators
Solar condenser extracts drinking water.
Battery-free operation in arid regions
Algae and terraforming
Oil yield 2 greater than other crops,
LED Plant Growth
Suitable for specialized cash crops
NASA Fe-Cr REDOX system.
Alternative to lead acid battery storage.
“Pico hydel” Efficiency ~ 55%. Needs high dynamic head.
Drive micro pumps using from wind turbines
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
4. How To Deal With A Steep Cross-disciplinary Learning Curve
Learning Approach
1. Two co-taught courses, set at 4xxx and 8xxx levels.
2. Continued knowledge base development using the courses and student reports
3. Development of testbeds through research Special Problems
Learning methods
•Extremely multidisciplinary projects
•Resources uploaded to course management website
•“EXTROVERT” cross-discipinary learning resources.
•Knowledge retention and transfer through Project Documents
•Weekly meetings encourage and motivate to learn the essentials.
•Graduate students as skills mentors.
•Individual mentoring through research projects
•Peer-to-peer learning: students seek out friends specializing in other schools
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Testbeds being developed at Georgia Tech MRES lab
Thermoelectric power generator
(example of eventual
application shown)
Symbiotic Biodiesel
Algae-Mushroom
Vertical axis wind turbine
1KW solar thermal-power
Retail Power Beaming
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
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Vertical Axis Wind Turbine
1. Bicycle-based 1m VAWT >270rpm,
>70 w (mechanical)
2. 2m 1kW VAWT for high coastal winds.
Issues:
1. Optimal tip speed ratio 2 to 5.
2. Variable power transmission
3. Nonlinear pitch control
4. Flexible blade operation
5. Benign failure modes
6. Hybrid devices: power conditioning,
storage
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Organizing Long-Term Progress With a Student Team
• Where tied to graduate degrees, progress is fast, and focused on a given testbed.
• Undergraduates often continue to work on a project in a fragmented manner, procrastinating
any learning effort and hence staying unaware of the basics of the project until the instructor
realizes the situation. With undergrad teams, progress is sporadic, and better distributed
between five testbeds
• Cumulative effort going into all 5 is substantial.
•Each semester, several students on Special Problems credit.
•Organized into a matrix of projects and teams.
•Typically, each student is assigned to 3 teams, and each team has 3 to 5 students.
• Graduate students learn the issues of all the testbeds and provide some oversight and
considerable assistance.
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Scheme
1. Matrix of projects and people, assigning each student to 2 to 3 projects.
2. Team coordinators accountable for organized progress.
3. Team Orientation Guide with safety and security rules and common sense practices.
4. Right To Know (RTK) on-line course conveys Institute’s seriousness about safety.
5. Weekly meetings Monday 7:45 or 8, each student expected to provide a succinct status report.
6. 16 assignments on course management website. Each assignment is to upload at least one
Project Document describing the up-to-date status of that project.
7. End of semester summary of individual contributions to all projects, demand introspection and
assimilation of lessons learned.
8. Student teams generally set own schedules.
9. Near-real-time reporting via phone and email is expected on experiment runs.
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Assessment Results
1. Approx. 30 total through courses, more than 150 through Special Problems, evolving continuum
of experience since 1985.
2. Students have the greatest difficulty with the concept of preparing and updating a Project
Document. Requires several interventions to get attention.
3. Most students eventually do a good job as team members.
4. Individual performance and skill sets vary widely.
Returning students for Special Problems Most students so far return for at least one more
semester unless professor advises otherwise
Publications co-authored by students
Increasing: 5 peer-reviewed papers, more underway.
Proposals from student projects
None so far.
Undergrads going on to graduate
school:
Several Special Problem students are in the School’s
Honors Program, and go on to the MSAE degree
Choice of employment in related fields
1 MS and 2 BS grads known to be in renewable energy
field.
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Conclusions
1. Fertile area of R&D at interface between space and the terrestrial micro renewable energy.
2. Highly cross-disciplinary area, demanding a steep learning curve from students and faculty.
3. A set of two courses has been developed to educate students in this area and to develop a
knowledge base. One course emphasizes breadth across technical, social and public policy
issues that go to the heart of the micro renewable energy marketplace, while the other is a
graduate course focused on the technical challenges and drawing on space technology.
4. Realities of micro renewable energy systems show that end-to-end efficiencies are small, even
with the extreme technical sophistication of space systems. Thus innovation must focus on
inexpensive, sustainable alternatives that retain the technical advantages of the space
systems and come close in figure of merit.
5. A set of 5 testbeds is being developed, to provide basic power conversion functions and then
enable adding on refined technology modules to enhance functionality for the same footprint.
6. Organizing student team efforts to carry on these testbed developments poses interesting
tradeoffs between timelines and breadth of effort.
7. The evolved method of organizing undergraduate student team activity is summarized.
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering
Acknowledgments
The author acknowledges the support from NASA under the
EXTROVERT cross disciplinary innovation initiative. Mr. Tony
Springer is the Technical Monitor.
Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering