Transcript 5th Meeting of the Global Forum on Sustainable Energy
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
19
th
– 23
rd
June 2006 Nairobi, Kenya
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Module 8: Solar Thermal
Jennifer Wangeci
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Solar Thermal
• Solar thermal energy = solar heat energy of solar energy) (heat application • Solar thermal technologies disseminated in African countries: Solar water heaters commercial buildings – water heating in residential and 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,
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Solar Water Heaters
• Fundamentals and Principles of Operation
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Photo credit: RETSCREEN ® International, 2004
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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 collector = heat transfer fluid is pumped through the solar
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Photo credit: Kenital, 2006
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
• Passive direct solar water heater • Passive = does not use pump • Direct = Circulates water through the collectors • Most common type used in Africa
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Photo credit: www.southface.org
• Active pump – uses • Open loop = direct system • Direct = Circulates water through the collectors
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Active = uses pump Indirect = Circulates heat transfer fluid (glycol) through the collectors
Photo credit: www.southface.org
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
• 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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Solar Water Heaters
Solar water heaters dissemination levels Photo credit: RETSCREEN ® International, 2004
Country
South Africa Morocco Egypt Botswana Kenya Mauritius Namibia
Installed Capacity (m
500,000 118,000 100,000 50,000 40,000 40,000 24,000
2 ) Country
Tunisia Libya Zimbabwe Malawi Zimbabwe Seychelles
Installed Capacity (m
18,000 17,300 10,000 4,800 4,000 2,400 Source: Karekezi and Kithyoma, 2005; World Energy Council, 2005; GEF, 2001, 2004
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Solar Water Heaters: Estimated Costs
Cost of 100-litre Solar Water Heating System in Selected African Countries (2001) Country Cost (US$) Country Cost (US$)
Botswana Eritrea 520 650-750 Namibia South Africa 610 550 Kenya Malawi Mauritius Mozambique 950 550 380 650 Swaziland Tanzania Uganda Zambia Zimbabwe 580 500 898 625 300 Source: AFREPREN, 2004
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Photo credit: RETSCREEN ® International, 2004
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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.
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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• Solar Drier from Jinja Photo credit: www.igadrhep.energyprojects.net
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
• Solar Mango Driers Photo credit: www.onecountry.org
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• Solar Drier
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
Photo credit: www.solarengineering.co.za
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
• 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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction 26
ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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.
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction 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'
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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ADB FINESSE Training Course on Renewable Energy & Energy Efficiency for Poverty Reduction
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
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