First solar direct-drive refrigerator receives WHO prequalification

by Janos Maté, SolarChill Project, and Steve McCarney, PATH On March 18, 2010, the World Health Organization (WHO) prequalified its first solar direct-drive vaccine refrigerator (Vestfrost model MKSO44). Ten years in the making, the SolarChillvaccine cooler operates with a compressor powered directly from sunlight. Instead of storing electrical energy in a battery, the refrigerator stores thermal energy in ice, and a thermostat maintains the temperature between the required 2º to 8ºC for vaccine storage. In low-sun situations or when power is completely disrupted, the insulated “ice battery” maintains acceptable temperatures for up to five days. An intelligent fan enhances the convection circulation of the cold air and is operated by a small rechargeable battery, which is recharged by solar power. The current generation of SolarChill is prequalified for 20º to 32ºC ambient temperatures. However, in field tests the units have operated under lower and higher ambient temperatures ranges of 10º to 42ºC. The direct current compressor and “ice battery” design makes SolarChill a groundbreaking technology. The lead batteries used in most solar refrigerators are expensive, short-lived (especially in hot climates), toxic to produce, and difficult to properly dispose of in remote regions. They represent a major obstacle to the uptake of solar technology in developing countries. A recent survey of solar-powered vaccine refrigerator performance found that over 60% of equipment failures are related to battery systems (McCarney, unpublished data, 2010). It is not a question of if a battery will fail, rather when. Batteries can fail due to improper design, poor installation, over use of the refrigerator, lack of maintenance, and delay of repairs. Programs relying on batteries must plan for and fund the inevitable repair and replacement costs of batteries. First to meet the solar challengeProject Optimize is taking action to improve the success of all solar-powered vaccine refrigeration. Efforts include documenting criteria for successful solar programs, reducing the need for active refrigeration, increasing battery life, and replacing batteries with thermal energy storage. In 2008 Project Optimize leveled a challenge at industry to develop direct-drive solar vaccine refrigerators. Five proposals were received, and three were awarded support for WHO prequalification test costs including the Vestfrost SolarChill. To prequalify the technology, WHO established two new categories for refrigerators in its performance, quality, and safety (PQS) standards. Project Optimize has actively supported the development of both the WHO PQS E03 RF05.2 for battery-free solar direct-drive refrigerators or combined refrigerator/icepack freezers and the WHO PQS E03 RF06.1 for solar direct-drive refrigerators or combined refrigerator/icepack freezers that require a small ancillary rechargeable battery for control purposes. The SolarChill (19.5 liter capacity) is the first to fit the latter category. Technology that does not heat the planetFor the SolarChill partnership, which was launched in 2001, gaining WHO prequalification marks a significant milestone in the effort to produce an environmentally friendly, battery-free, affordable solar refrigerator. Prior to the establishment of the new PQS categories, all prequalified WHO refrigerators using compressors included hydro-fluorocarbons (HFCs) as refrigerants. HFCs are bioaccumulative pollutants that contribute to ozone depletion and climate change. Concerns about atmospheric concentrations of HFCs and their significant role in climate change have made them less than ideal technologies for health systems. Instead of using fluorocarbons, SolarChill uses “GreenFreeze” hydrocarbon technology developed by Greenpeace in 1993 for blowing insulation foam and for the refrigerant, which makes them safe for the ozone layer and the climate. The SolarChill Project partners[1] have no commercial interest in the project. Their sole mandate is to develop the public domain technology, make it freely available to interested manufacturers worldwide, and promote its uptake internationally. The SolarChill vaccine cooler is currently available through the large Danish appliance manufacturer Vestfrost. In 2010, the SolarChill partnership launched large-scale demonstration and technology transfer projects in Colombia and Kenya with PATH taking the lead role in implementing the demonstration projects in both countries. These projects are funded by the Global Environment Facility through the World Bank. The WHO prequalification of SolarChill enables low- and middle-income countries that require earth-friendly, less-costly, and reliable solar refrigeration solutions to specify SolarChill technologies for their vaccination programs. In a related development, the SolarChill Project is testing a larger model of direct-drive solar refrigerator, operating on the same principles, for the purpose of domestic and light commercial food refrigeration. The SolarChill Project thus bridges health, development, and environmental concerns through an innovative technology. To learn more about the SolarChill refrigerator and the partnership that made it happen, visit http://www.solarchill.org. [1] The SolarChill Project partner organizations are the Danish Technological Institute, the German Government Development Agency, Greenpeace International, PATH, United Nations Environment Programme, the United Nations Children’s Fund, WHO, and the World Bank. Please see http://www.solarchill.org “Contacts” for the names and contact information of individual representatives.