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

1. Testbeds Connecting Space Technology To Terrestrial Renewable Energy Narayanan KomerathProfessor, Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, Atlantakomerath@gatech.edu 1

2. Thrust of the Paper: How to Learn In a New Cross-Disciplinary Area Fertile area of R&D at interface between space and terrestrial micro renewable energy. End-to-end efficiencies are small, even with space systems. Innovation focus on sustainable alternatives for high Figure of Merit. Steep cross-disciplinary learning curve. Approach based on courses, testbeds, knowledge base development, learning resources, individual and team projects. Testbeds approach enables hands-on experience, test cases for simulation, and enables continued advances to provide greater functionality for the same footprint. Organizing testbed developments poses tradeoffs between timeliness, depth and breadth. Evolved method of organizing and assessing student team activity is summarized.

3. Fertile area of R&D at interface between space and the terrestrial micro renewable energy. Terrific R&D! NO MARKET!!!! • ISRU customer is the government. • Devices represent the best of human technology. Space ISRU research MICRO RENEWABLE ENERGY SYSTEMS Terrestrial Micro Renewable Power Global Market NO R&D!!!!

4. 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.

5. 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

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

7. 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

8. Testbeds being developed at Georgia Tech MRES lab Thermoelectric power generator (example of eventual application shown) Symbiotic Biodiesel Algae-Mushroom Vertical axis wind turbine Retail Power Beaming 1KW solar thermal-power 11

9. Vertical Axis Wind Turbine • Bicycle-based 1m VAWT >270rpm, • >70 w (mechanical) • 2. 2m 1kW VAWT for high coastal winds. • Issues: • Optimal tip speed ratio 2 to 5. • Variable power transmission • Nonlinear pitch control • Flexible blade operation • Benign failure modes • Hybrid devices: power conditioning, • storage

10. 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.

11. Scheme • 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. • Student teams generally set own schedules. • 9. Near-real-time reporting via phone and email is expected on experiment runs.

12. Assessment Results • Approx. 30 total through courses, more than 150 through Special Problems, evolving continuum of experience since 1985. • Students have the greatest difficulty with the concept of preparing and updating a Project Document. Requires several interventions to get attention. • Most students eventually do a good job as team members. • Individual performance and skill sets vary widely.

13. Conclusions • 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.

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