ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction

1. ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction 19th – 23rd June 2006 Nairobi, Kenya

2. Module 8:Solar Thermal Jennifer Wangeci

3. Overview • Solar Water Heaters • Fundamentals and Principles of Operation • Types of solar water heating systems • Dissemination levels • Estimated costs • Project considerations • Case studies • Solar Driers • Fundamentals • Case studies • Solar Cookers • Fundamentals • Case studies

4. Solar Thermal • Solar thermal energy = solar heat energy (heat application of solar energy) • Solar thermal technologies disseminated in African countries: • Solar water heaters – water heating in residential and commercial buildings • Solar cookers/ovens – cooking in households and institutions • Solar driers – drying agricultural produce such as fruits, fish and vegetables • Other solar thermal applications = water purification, space heating, space cooling,

5. Solar Water Heaters: Fundamentals and Principles of Operation • Components • Collectors • Storage tanks • Electric pumps (depending on the system) • Principles of Operation • Sun heats a heat transfer fluid in the collector • Heated fluid heats water • Hot water held in the storage tank ready for use • Amount of water heated depends on • Type and size of system • Solar radiation and insolation at the site • Proper installation • Tilt angle and orientation of collectors

6. Solar Water Heaters • Fundamentals and Principles of Operation Photo credit: RETSCREEN® International, 2004

7. Solar Water Heaters: Types of Systems • Active vs. Passive • Terms refers to whether the systems rely on pumps or only thermodynamics to circulate water • Active = uses an electric pump to circulate the heat-transfer fluid between the collector and storage tank • Passive = relies on gravity and the tendency for water to naturally circulate as it is heated • Direct vs. Indirect • Terms refer to whether water or heat transfer fluid (e.g. antifreeze) is pumped through the solar collector • Direct = water is pumped through the solar collector • Indirect = heat transfer fluid is pumped through the solar collector

8. Passive direct solar water heater • Passive = does not use pump • Direct = Circulates water through the collectors • Most common type used in Africa Photo credit: Kenital, 2006

9. Active – uses pump • Open loop = direct system • Direct = Circulates water through the collectors Photo credit: www.southface.org

10. Active = uses pump Indirect = Circulates heat transfer fluid (glycol) through the collectors Photo credit: www.southface.org

11. Closed loop = indirect system • Indirect = Circulates heat transfer fluid (water or diluted antifreeze solution) through the collectors • Uses a heat exchanger to transfer the heat to water Photo credit: www.southface.org

12. Solar Water Heaters Solar water heaters dissemination levels Photo credit: RETSCREEN® International, 2004 Source: Karekezi and Kithyoma, 2005; World Energy Council, 2005; GEF, 2001, 2004

13. Solar Water Heaters:Estimated Costs Cost of 100-litre Solar Water Heating System in Selected African Countries (2001) Source: AFREPREN, 2004 Photo credit: RETSCREEN® International, 2004

14. Solar Water Heaters: Benefits & Barriers • Benefits • Solar water heaters offer large potential savings • Owners saving as much as 50% to 85% annually on their utility bills over the cost of electric water heating • Reduced need for gas or electricity to heat water • Cushioned from fuel/electricity shortages • Reduced petroleum import bill • Environmental benefits • Barriers • Cost – beyond the reach of most people • Attitude – solar water heaters are for the rich

15. Solar Water Heaters: Project Considerations • Factors for successful projects: • Large demand for hot water to reduce importance of fixed costs • High energy costs (e.g. natural gas not available) • No reliable conventional energy supply • Strong environmental interest by building owner/operator • Utility-based dissemination of solar water heaters can be very effective • Daytime hot water loads require less storage • Lower cost, seasonal systems can be financially preferable to higher-cost year-round systems • Maintenance similar to any plumbing system, but operator must be committed to timely maintenance and repairs • Domestic vs. commercial (hospital, schools, hotels) application

16. Solar Water Heaters: Ethiopia Case Study • Solar water heaters increasingly economically feasible due to: • Increase in oil prices and electricity tariffs • Removal of end-use supply subsidy of oil • Since 2000, 10 private companies have entered the SWH market and installed more than 880 units • With current electricity prices, SWH investment cost can be paid back within 6 months • Advantages of SWH compared to electric boilers: • Better durability • Lower bills • Now running costs • Low maintenance costs

17. Solar Water Heaters: Ethiopia Case Study • Disadvantages of SWH compared to electric boilers: • Not being able to get hot water especially at night (for those without a storage tank) • Technical problems associated with locally manufactured SWHs (before improved standards). Initial installers were poorly trained plumbers who adversely affected public reputation of technology • Challenges faced in SWH dissemination: • Prices – beyond the cost of most individuals • Low Government and NGO intervention/involvement • Involving utilities – requires good data on contribution of electric heating to peak loads.

18. Solar Driers • Developed as an alternative to open-air sun drying and other conventional drying methods • Mainly used for drying agricultural produce such as fruits, vegetables and fish • There are two common types of solar driers: • Direct solar drier: • Closed insulated box in which both solar collection & drying takes place • Solar radiation passes through transparent glass/plastic into drying compartment • Moisture exits through vents at the top of compartment • Indirect solar drier • Flat plate collector and separate drying chamber • Air pre-heated in flat plate collector and rises to drying chamber to dry

19. Solar Driers: Benefits & Barriers • Benefits: • Reduce post harvest losses • Increase quality of product • Time marketing of product enabling one to fetch the best price possible • Help reduce environmental degradation caused by use of fuel wood and fossil fuels • Reduce cost associated with using fuel wood and fossil fuels -> reduces the cost of the product • Barriers: • Cost – beyond the reach of most individuals • Longer drying times – compared to fuel wood and fossil fuel

20. Photo credit: www.igadrhep.energyprojects.net • Solar Drier from Jinja • Solar Mango Driers Photo credit: www.onecountry.org

21. Solar Drier Photo credit: www.solarengineering.co.za

22. Solar Driers: Case Studies • Uganda • Solar driers introduced household storage of fruits & vegetables • Rural groups preferred them for income generation • Used by women groups for fruits and vegetables drying for export (40 tonnes of dried fruit exported in 2000) • Within 3 years, more than 50 groups had taken up the technology • Impact: Increased incomes, productivity and employment creation • Kenya • Solar driers used by women’s group to dry mangoes for export • In 13 weeks, each woman in the group earned Ksh. 6,000 (US$ 80) • Impact: Increased incomes and productivity

23. Solar Driers: Case Studies • Burkina Faso • Solar driers used by women’s groups and cooperatives to dry fruit for export • To maximise benefits from solar drying, the groups and cooperatives formed the Circle of Driers (CDS) • In 2003, CDS exported 68 tonnes of dried mango, 10 tonnes of juice and 8 tonnes of syrup • Impact: increased incomes, and employment creation • Nigeria • Solar drying of fish introduced to replace traditional method of open-air sun drying • Impact: increased quality of fish thus increased incomes and profit, reduced demand for firewood for smoking fish

24. Solar Cookers • Parabolic cooker • Consists of 3 main parts • Parabolic reflector – concentrates the sun onto en small area • Control arm – allows the reflector to be set facing the sun, holds the pot at a focal point • Stand – holds the reflector + control arm together, allows cooker to be rotated to follow the sun • Under strong sunlight, a litre of water can be brought to a boil in about 10 minutes

25. Solar Box cooker • Consists of: • Insulated box • Transparent top • Reflective lid • Use plane reflectors to reflect radiation through a glass window into an insulated cooking box • Make use of the greenhouse effect to trap the heat behind the glass window inside the box • Solar cookers are completely sealed to prevent heat from escaping • They are thickly insulated with suitable material which allows them to retain the heat energy

27. Solar Cookers • Solar cookers good for institutions (schools, refugee camps) • Dissemination levels still low • Key barriers include: • Slow cooking time compared to biomass stoves • inconvenience of use (cooking in the sun) • socio-cultural constraints (cooking in the open) • Cost • Only effective during hours of strong sunlight – another stove is required for cloudy periods or during morning and evening hours

28. Solar Cookers • But technology useful for pre-heating water to be used for cooking • Can also be a useful for purifying water for potable applications (up to 70 Degrees centigrade can eliminate up to 90% of water borne pathogens) • Solar distillers which operate on similar principle as solar cookers can produce distilled water for use at household, dispensaries and batteries.

29. Solar Cookers: Case Study – Kakuma Refugee Camp • Location: • North Western Kenya • Background: • Home to 100,000 refugees • Extremely dry and wood is very scarce • Majority of families cook on wood and charcoal fires • Wood cannot be sourced locally • Refugees not allowed to collect firewood from outside the camp - have to rely on monthly rations of wood for cooking • The 8-10 kg they are given is barely enough to last a month. • Solar Cookers International (SCI) started a pilot project in Kakuma in 1995 that provided refugees with portable, lightweight solar cookers called 'CooKits'

30. Solar Cookers: Case Study – Kakuma Refugee Camp • The project distributed the CooKits and taught people how to use them effectively • The CooKit is cheap, lightweight, simple and very easy to use • Requirements - blackened pot with a lid and a clear plastic bag • How it works: • Food is put into the pot, covered with the lid and then put inside a plastic bag • The whole lot is then placed in the centre of the cooker and left in the sun • Kakuma’s climate has made it ideal for using the CooKits • Impact - reduced the need for using firewood in the camp

31. Solar Cookers: Case Study – ITDG Kenya Review Survey • Major factor in adoption of solar cookers in Kenya is degree to which the technology can be used to undertake existing traditional cooking activities • Of people reviewed: • 90% found the cooker to be too slow • 54% complained that it could not cook their preferred dishes, and in many cases could not cook enough for all family members • 67% has misgivings about leaving their food or cooker unattended and so only used them when they were present to watch over them • 53% see the cooker as an expensive item • In 7 out of 10 project areas visited firewood is freely available and there is little incentive for people to buy or use solar cookers • Socio-economic factors appear to influence adoption more than technical features • Wrong area or target group affected adoption and dissemination