Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

Testbeds Connecting Space Technology To Terrestrial Renewable Energy

Narayanan KomerathProfessor, Daniel Guggenheim School of Aerospace Engineering,

Georgia Institute of Technology, Atlanta

komerath@gatech.edu

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Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

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.

Thrust of the Paper: How to Learn In a New Cross-Disciplinary Area

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

Space ISRU research

Terrestrial Micro Renewable Power

Global MarketNO R&D!!!!

MICRO RENEWABLE ENERGY SYSTEMS

Terrific R&D!NO MARKET!!!!

•ISRU customer is the government. •Devices represent the best of human technology.

Fertile area of R&D at interface between space and the terrestrial micro renewable energy.

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

•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.

Requirements for terrestrial micro energy systems

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

1. Low thermodynamic efficiency of heat engines with small temperature gradients2. Large surface area per unit mass, resulting in high friction and heat transfer losses.3. Highly fluctuating power4. 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

2. Efficiency is small even for Space power systems!Issue is to achieve high Figure of Merit (but not above 1!!!!)

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

Space Technology Terrestrial Testbed IncorporationHigh intensity solar cell 3KW Hybrid solar PV/thermal generatorOptical waveguides to convey solar power directly use point 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 T ~ 6 C. Various fuels & heat sources. Thermo acoustic cooker-refrigerator

Atmospheric water generation Solar condenser extracts drinking water. Solar vapor-condenser refrigerators 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

3. Innovation focus on sustainable alternatives that achieve high utility.

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

1. Two co-taught courses, set at 4xxx and 8xxx levels. 2. Continued knowledge base development using the courses and student reports3. Development of testbeds through research Special Problems

Learning Approach

Learning methods

4. How To Deal With A Steep Cross-disciplinary Learning Curve

•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)

1KW solar thermal-power

Vertical axis wind turbine

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Retail Power Beaming

Symbiotic Biodiesel Algae-Mushroom

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

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 transmission3. Nonlinear pitch control4. Flexible blade operation5. Benign failure modes6. Hybrid devices: power conditioning, storage

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

• 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.

Organizing Long-Term Progress With a Student Team

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

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.

Scheme

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

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.

Assessment Results

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

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.

Conclusions

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

The author acknowledges the support from NASA under the EXTROVERT cross disciplinary innovation initiative. Mr. Tony Springer is the Technical Monitor.

Acknowledgments