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When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study.
Leila A Haidari1, Shawn T Brown1, Patrick Wedlock2
1HERMES Logistics Modeling Team, Baltimore, MD and Pittsburgh, PA, USA; Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, PA, USA.
Vaccine
|April 3, 2017
Summary
Solar refrigerators can be cost-effective for vaccine storage, even with infrequent power outages. Their economic viability depends on outage frequency, duration, and refrigerator price, supporting broader vaccine supply chain resilience.
Area of Science:
- Health Systems Research
- Supply Chain Management
- Renewable Energy Applications
Background:
- Gavi recommends solar refrigerators for vaccine storage in areas with limited electricity (under 8 hours/day).
- World Health Organization (WHO) guidelines for vaccine storage are more conservative.
- The study investigates the cost-effectiveness of solar refrigerators in areas with less frequent electrical outages.
Purpose of the Study:
- To evaluate the economic value of solar refrigerators compared to electric refrigerators in vaccine storage.
- To determine the specific conditions of electrical outages (frequency and duration) under which solar refrigerators become cost-saving.
- To inform guidelines for vaccine cold chain infrastructure investment.
Main Methods:
- A computational model (HERMES) of the Mozambique routine immunization supply chain was utilized.
- Simulations compared solar refrigerators against electric mains-powered refrigerators at various supply chain levels.
- Scenarios assessed different frequencies and durations of electrical outages and varying solar refrigerator costs.
Main Results:
- At current price premiums, solar refrigerators are significantly more expensive annually than electric ones.
- Solar refrigerators become cost-saving with one-day outages occurring >5 times/year or two-day outages occurring >3 times/year (district level).
- Reduced solar refrigerator costs (75% premium) make them cost-saving with fewer outages (e.g., one-day outages >1 time/year).
Conclusions:
- The study supports existing WHO and Gavi recommendations for solar refrigerators.
- Solar refrigerators can offer cost savings over electric alternatives even with less frequent electrical outages.
- Specific outage thresholds and price points determine the cost-effectiveness of solar refrigerators for vaccine storage.