Technologies for heating, cooling and powering rural health facilities in sub-Saharan Africa

1. International Conference on “Low-cost electricity generating heat engines for rural areas” Nottingham April 2nd 2012 Technologies for heating, cooling and powering rural health facilities in sub-Saharan Africa Matt Orosz PhD Candidate Civil and Environmental Engineering Amy Mueller PhD Candidate, MIT Bertrand Dechesne MS Mechanical Engineering U.Liege Prof. Harold Hemond MIT

2. 1.5 Billion

4. STG International We see an opportunity to provide electricity and thermal energy to rural clinics and schools in remote regions of developing countries. Renewable - Economical - Sustainable

5. Unelectrified Rural Clinics and Schools 20,000 3,700 2,500 Source: Solar Millennium AG (map), STG (clinics) 4,500 A $2.7b Opportunity to make the world a better place

6. Application:Powering rural health clinics Typical Lesotho clinic: • 50-100 patients/day • 3 nurses + orderly • 4-10 Clinic & staff buildings • No electricity • No hot water • combustion heating - cold in the winter • Poorly insulated • Roughly 200m2 footprint 6

9. 8250kWh/year

10. Technology Motivation Micro-CSP Concentrated Solar Power with Organic Rankine Cycle Distributed applications On-site cogeneration Renewable Local manufacture and maintenance Well proven at MW scale LCOE ~ $0.20/kWh Not available at smaller scale

11. STG Technology: ThermoSolar Trigeneration USPTO patent issued March 2012

13. Curzon-Albhorn

14. Low cost sensible storage: Quartzite pebble bed Cost of thermal storage ~ 20-80 USD kWh-1 Battery Storage > 150 USD kWh-1

15. STG micro-utility for Rural Schools & Clinics • 2 active demonstration sites (Africa and FL) • 3kWe ORC 75m2 • Built in Africa by trained local technicians

16. Micro-CSP Innovations Size: 100x smaller than other commercial thermosolar technologies, clinic and school scale = viable Leveraged OEM Components – global supply chain for HVAC parts Serial Expanders – patented method for high efficiency solar conversion Autonomous Control System – key enabler for remote utility operation Locally Manufacturable – spillover benefits to local economy Distribution Model – micro-utility / PPA saves $ and improves reliability

17. Adapting a scroll compressor for expander mode: Modifications to existing equipment Source: Harada 2010 Development of a Small Scale Scroll Expander.

18. Adapting a scroll compressor for expander mode: • Remove check valves and bypass valves • Optimize pressure port and support sealing piston with springs • Install Union ports • Install flanges to reseal the can Source: Harada 2010 Development of a Small Scale Scroll Expander.

19. Adapted compressor expander Benchmarking – The isentropic efficiency is unknown, so empirical determination is necessary to predict performance and size the unit. MIT and U.Liege benchmarked several types of compressors Generally, scroll machines are high efficiency, and available in range of displacements

20. a. A typical HVAC scroll compressor that can be modified to operate as a scroll expander in an ORC. b. Modeled and observed performance data for two HVAC scrolls operating independently in an ORC. c. Modeled and observed data for the same two scrolls operating in series in an ORC d. CAD model of a high volume ratio scroll prototype based on increasing numbers of wraps – eventually the unit ‘pancakes’ to a large diameter at a high volume ratio. e. Derating of induction generator as a function of nameplate rating as a motor. This becomes important in the case of hermitically sealed HVAC expanders coupled to the induction machine. f-i. show results of geometric simulations using the fundamental scroll equation. The design space of parameters (radius orbital radius, coefficients of theta, etc.) is plotted with respect to figures of merit, e.g. normalized volume ratio divided by diameter to obtain the ‘packing factor’ with respect to volume ration. j. an optimized scroll expander geometry based on the scroll parameter space explored in f-i. k. The intrinsic scroll equation sx as a function of the angle (theta) of the tangent vector.

21. Trigeneration

22. Temperature and DD Source: NASA http://eosweb.larc.nasa.gov

23. Economic Analysis Assumptions: Discount rate: 4% 15 Year lifetime 330 days operation per year 55 days autonomy 25 kWhe 118-138 kWhtday -1 f=1.5/0.3 (Diesel/PV) a-0.25

24. Competing Technologies: 25kWh/day Trigeneration: electricity, heating, cooling Alternative options for hot water, heating and cooling (vapor compression or chiller) incur additional costs. Propane/LPG $12-30k NPC to operate for 15 years Carbon Credits Annually: Passive solar 2800L diesel $20-60K upfront cost for system matching STG ORC 7.5 tons CO2

26. Distribution Model: Micro-Utilities USD10k installation fee and 5 year USD 9k/year PPA per site. Cost to install is US$36k Maintenance responsibility is on micro-utility so clinics/schools can focus on their primary missions. Marketing to financiers. Sales to implementing agencies: 26

28. Active Field Demonstrations Eckerd College, FL Lesotho Government of Lesotho Ministry of Science and Technology Ministry of Health

29. STG core team: 3 PhDs , 3 MScs, 1 MBA 3 Mechanical Engineers Working in Africa Since 2005