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2 Degrees 24 Hours - Nigeria
Immunisation against such diseases as tetanus, hepatitis B and polio is generally agreed to save many lives worldwide. However, a major problem facing medical staff is the lack of suitable cool storage as vaccines have to be kept at the right temperature to remain effective. In many developing countries this is a serious problem but KXN Nigeria Ltd has worked on a solution – solar refrigeration.
Health Issues
Nigeria is Africa's most populous country, but with some of the worst poverty linked health indicators in Africa, for example it is currently one of the last four countries where the wild poliovirus virus is endemic. The National Programme on Immunization (NPI), whose objectives are to eradicate, eliminate and control childhood and other vaccine preventable diseases through adequate routine immunisation activities, has faced the difficulty that existing vaccine storage facilities were inadequate.
During transportation and storage, vaccines have to be kept at a controlled temperature within limits of 2˚ and 8˚C right up to the moment of use . Where freezers were connected to mains electricity, frequent power cuts made them unreliable for storing vaccines. Small diesel or petrol generators could be used to power freezers to make ice for cool boxes, but they could not be left unattended overnight because there were issues over the safety of fuel storage, noise and fumes and they were liable to overheating, mechanical breakdown and theft. This means they were not suitable for the round-the-clock cooling which the vaccines demand and were are best used to provide emergency charging of batteries. Large generators, which were only likely to be present in central, zonal and state stores, were too expensive in fuel and maintenance costs to keep running round the clock. Refrigerators run on bottled gas were available in some areas, but supplies were expensive and difficult to obtain. Kerosene-powered refrigeration had proven troublesome with fuel quality, availability and safety. Although Nigeria is a major oil producer, it experiences frequent fuel shortages and consequent price spikes so diesel and petrol are often not available.
The series of storage and transport links for keeping vaccines in good condition until the point of use is known as the vaccine 'Cold Chain'. It is a major logistical undertaking in areas where electricity supplies are non-existent or erratic. It has been estimated that, with a refrigerator holding 75,000 oral polio doses, a potential $5,000 worth of precious vaccine could be ruined if the power went off. With other sources of power being unreliable, expensive or inadequate, solar power provides a possible solution to this health care issue wherever the sun shines. Although solar power is not cheap, the expense pales by comparison with the cost of vaccines being spoilt through not being kept cold.
Solar Solution
The amount of sunlight available in Nigeria is sufficient for the hi-tech solution of harnessing the sun's energy. Solar rays can be converted to electricity via small photovoltaic (pv) panels which have the capacity to power refrigerators. Even when there is no mains electricity supply, or when there is a failure of the mains power supply, a solar refrigerator can keep vaccines fit for use.
Photovoltaic refrigerators operate on the same principle as normal compression refrigerators but incorporate low voltage (12 or 24V) direct current (dc) compressors and motors, rather than mains voltage ac types. A photovoltaic refrigerator has higher levels of insulation around the storage compartments to maximise energy efficiency, a rechargeable battery bank for electricity storage, a charge regulator or controller that regulates the flow of electricity to the battery to protect it from over-charging and over-discharging, both of which shorten battery life. The controller can also shut down the refrigerator if battery voltage is too low (though modern solar refrigerators incorporate ‘low voltage disconnects’ disconnects’ (LVDs) which prevent damage to the battery by disconnecting before they run dry). A typical refrigerator layout is shown in Figure 1.
Figure 1: Solar refrigeration layout.
Most refrigerators include a freezer compartment for icepack freezing. Other systems have separate units to provide solely for refrigeration or freezing. Generally the battery used, on account of cost, is the lead acid type - long life, deep cycle batteries are preferred. It is useful to have an audible alarm or warning light to signal when battery voltage becomes low.
The solar panel array can be mounted on a roof or on the ground. The array size for a refrigeration system is calculated to meet the power requirements of the system, given the history of sunshine (solar irradiance data) at the proposed site. The typical requirement is 150 to 300 Wp of photovoltaic modules. The 4-module array offers great flexibility, e.g. with a 12 V systems you can have:
240 Wp array = 4 x 60 Wp modules or 3 x 80 Wp or 2 x 120WP
150Wp array = 2 x 75 Wp
300 Wp array = 4 x 75 Wp
It is better to err on the side of ‘over-sizing’, as the larger array charges a battery quicker, and a smaller battery can be substituted in an emergency. For example in the event of failure icepacks can be removed from the freezer compartment to the fridge, and that should keep the contents acceptably cool for a few daysemergency . At 32˚C an RFVB134a needs 32 Ah/day which it draws from the battery. A minimum size array will take one average day (worst month) to replace that. However, in a prolonged period of low sunlight (insolation), as in some areas like Calabar along the coast when it can rain non-stop for days, the battery reserve is drawn on because the replacement rate is less than drawdown. So a larger array would be more capable to keep a battery topped up under such conditions.
The energy consumption of a photovoltaic vaccine refrigerator is typically 400 to 800 watt-hours per 24 hours for a 100-litre refrigerator without icepack freezing and at +32°C ambient temperature. At +43°C ambient temperature and freezing 2kg of icepacks per 24 hours the energy consumption of the same refrigerator would rise to about 900 to 1900 watt-hours per 24 hours. It is important not to overload a solar refrigerator as this increases energy consumption considerably.
A good vaccine refrigerator should be able to maintain correct internal temperatures for at least ten hours in the event of being disconnected from the battery and solar array. Furthermore a capacity to run the refrigerator for five days without sun is recommended.
KXN Nigeria
In 2001 NPI, advised by KXN Nigeria Ltd, set out a strategy for a national chain for vaccine storage and distribution. It selected the Sun Frost RFVB-134a 134a vaccine refrigerator and freezer as this had proven reliable in earlier programmes and had the optimum specification for the climatic conditions. However, it needed companies to carry out solar installations to a satisfactory level. The installations had to be easy to install, reliable and require minimum maintenance. Local contractors were selected as suppliers for the complete solar refrigeration system, but unfortunately NPI did not publish a comprehensive specification for the tender, and excluded both recommended suppliers and their local distributors. The result was inconsistency in delivered system components, and purchase costs about 30 per cent higher than they could have been.
KXN had designed a ‘one size fits all’ system for 3.0 kWh/M2/day, guaranteed five-year battery and controller life, with a 20-year minimum power output from high performance pv modules. The system has six days’ autonomy so that, in areas of seasonal access or of long periods of rainfall (during the rainy season) causing low insolation, in case of a malfunction there would be sufficient time to get to those remote locations to fix the fault.
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Sunfrost Frost RFVB-134a vaccine refrigerator
donated by Rotary International in 2002 |
An imaginative collaboration between solar entrepreneurs KXN, the University of Maiduguri in Borno State, and BP Solar has enabled a dozen young engineers to be trained. They have installed 165 solar refrigerators in 90 villages spread over four northern states, including Borno. Each refrigerator stores enough vaccine to inoculate no fewer than 37,000 children against diseases such as polio, tuberculosis (TB), diphtheria and pertussis (whooping cough). Many of them come from semi-nomadic peoples not easily reached by routine health care programmes, so the solar refrigerators are particularly valuable here. For its work on solar refrigeration KXN Nigeria has been awarded an Ashden Award for Sustainable Energy. At a prestigious Awards ceremony Anthony Ighodaro (Director of KXN) was presented with his award by The Rt Hon Hilary Benn MP Secretary of State for International Development, and at a reception the following day was presented with his certificate by HRH Prince of Wales.
Improvements
Although this programme has been successful there are some issues that have to be addressed to ensure its long term viability, such as:
- ensuring consistency of supplies – If inappropriate or inadequate components are used this could affect the reliability of the system.
- on-going maintenance costs – Although the refrigerators were supplied free maintenance costs were not covered. Agreements must be made to ensure these are considered as part of the installation package.
- training solar installers – There are few trained installation experts in Nigeria. KXN worked in collaboration with the University of Maiduguri to provide comprehensive training on pv basics, followed by hands-on experience at actual sites.
- monitoring the performance of the pv systems – This needs to be carried out regularly to ensure they are working effectively. It is suggested that a pilot project comprising the existing installations is set up, and a database created to monitor the systems. The purpose would be to improve the quality of the cold chain: detect failure early, trigger rapid technical intervention, optimise a spares inventory, improve installer and maintenance performance, and deter theft.
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Training exercise, Borno State Hotel, Maiduguri, Borno State. |
| credit Ashden Awards for Sustainable Energy |
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Future
The success of the scheme has shown that there is real potential to extend the uses of solar power in remote areas on a self-sustaining, commercial basis.
These might start with services such as solar charging of the refrigerator and wireless/satellite phone batteries, to support the maintenance of the solar vaccine refrigerators. This could lead naturally to battery rental for small lighting and solar home systems, and solar water pumping and distribution, bringing educational and health benefits.
Perhaps the most useful applications in the medium outlook, in terms of numbers affected and economic improvement, would be communication centres, using mobile and satellite phones to access the outside world, even the internet. As well as helping to end the social isolation of remote communities, these could provide vital emergency health links, as well as economic benefits. For example, they could enable local food producers to keep track of market prices for their produce, so helping them maximise their own returns.
For the project to last, training locals is essential. Once trained, they should be able to construct a variety of solar systems and generate an income in addition to their earnings from maintenance services. If these people can also receive an additional income from other entrepreneurial projects the future of solar energy is promising.
Acknowledgements
Hands On would like gratefully to acknowledge the assistance of Anthony Ighodaro, Managing Director, KXN Nigeria Ltd in the preparation of this case study.
Further Information
Participating Organisations
KXN Nigeria Ltd
Sales: sales@solarsolve.com
Customer Support: service@solarsolve.com
BP Solar International Inc
Website: http://www.bp.com/modularhome.do?categoryId=4260&contentId=7004852
University of Maiduguri
Bama Road
Maiduguri
Nigeria
Website: http://www.unimaid.org/
References
Ighodaro A. Proceedings 19th. European Photovoltaic Solar Energy Conference, Paris 2004, Vol. 3 (2004) 3357. ‘Levering the national programme on immunisation’.
Ighodaro A. Proceedings 20th European Photovoltaic Solar Energy Conference, Barcelona, 2005. ‘Levering the national programme on immunisation for sustainable community benefits’.
Further Reading
Practical Action Technical Brief: Solar (PV) refrigeration of vaccines
http://www.practicalaction.org/docs/
technical_information_service/
solar_refrigeration_vaccines.pdf
Practical Photovoltaics: Electricity from solar cells. Richard J. Komp,
Chelsea Green Pub Co, 2002
Contacts
World Health Organisation
The Department of Vaccines and Biologicals of the World Health Organisation, in its Immunisation Systems Series publishes, every two years, a document entitled 'Product Information Sheets'. This catalogues equipment that has undergone tests to verify their performance is of a standard acceptable to the World Health Organisation (WHO) and United Nations Children Fund (UNICEF). The document may be obtained from: The V & B Document Centre, Department of Vaccine and Biologicals, World Health Organisation, CH-1211 Geneva 27, Switzerland. (Website: http://www.who.int/vaccines-documents, Email: vaccines@who.int )
Ashden Awards
The Ashden Awards reward outstanding, inspirational and innovative local sustainable energy schemes that both protect the environment, tackle climate change and make real improvements to people's quality of life. They are designed to encourage wider take-up of local energy solutions worldwide - proving to the public and policy makers alike that such schemes offer viable, practical ways of tackling poverty, resource shortages and climate change.
Website: http://www.ashdenawards.org/
Resources
Practical Action Technical Information Service
Schumacher Centre for Technology & Development
Bourton Hall
Bourton-on-Dunsmore
Warwickshire CV23 9QZ
UK
Tel: +44 (0)1926 634462
Fax: +44 (0)1926 634401
Website: http://www.practicalaction.org/
?id=technical_information_service
ITDG Publishing
Schumacher Centre for Technology & Development
Bourton Hall
Bourton-on-Dunsmore
Warwickshire CV23 9QZ
UK
Tel: +44 (0)1926 634501
Fax: +44 (0)1926 634502
E-mail: marketing@itpubs.org.uk
Website: www.itdgpublishing.org
Related Hands On Case Studies
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http://www.handsontv.info/series3/
fuel_for_thought_reports
/thecoldchain_bangladesh.html
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