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Botswana: A Hypothetical Case for a Rural Health Clinic

Map of Botswana and its neighbors.

A hypothetical clinic in the Kalahari Desert of Botswana currently has a small refrigerator, lights, hematology mixer, microscope, computer, and communications equipment. It is determined that the average daily load of the clinic is 13 kWh per day with additional load of 2 kWh per day expected in the near future. The clinic is not connected to the grid and currently utilizes a diesel generator to partially meet its energy needs. An international donor agency has been working with this clinic to improve local health care service delivery and would like to explore different options for upgrading its power generation systems.

Several different modeling tools have been developed which allow a user to compare different energy generation options for this facility. For this example, we use the HOMER program, specifically developed by the U.S. National Renewable Energy Laboratory to analyze stand-alone systems that include renewable energy components. The HOMER model can be used to compare costs for a variety of different energy generation systems that can meet 100% of this clinic’s load. We considered systems with combinations of the components shown in the figure above: generator, PV, AC/DC converter (inverter) and batteries.

In addition to the load data already calculated for this clinic, other site-specific information needed for this model is renewable resource availability, cost of fuel, and component costs. Appropriate solar radiation data for this location is automatically accessed by HOMER from the NASA database. Component costs can be estimated based on in-country information.

The resulting cost estimates are shown in the table below, which ranks a variety of alternative system designs by the lifetime cost of energy per kWh. The lowest cost system is a PV-diesel-battery hybrid system. The calculations demonstrate that because of fuel and maintenance costs, the system with the lowest capital cost is not the system with the lowest lifetime cost of energy. A diesel-battery system costs 13% more than this hybrid system because the added fuel cost over the life of the system is more than the savings in initial PV investment, and a PV-battery system costs about 28% more than the least-cost design. Notice that the cost of energy from a diesel system with no batteries is over twice the cost from a diesel-battery system. The addition of batteries to a diesel system are often a good investment in terms of fuel savings.

Comparison of Alternative System Designs, diesel price $0.80/L

The total net present value of costs (NPC) of the least-cost system and its components is shown below. The fuel cost component is very small because the generator runs only 113 hours during the year. Notice that all technologies have significant O&M requirements, totaling about $300 per year. If sufficient funds are not available to cover these maintenance costs, or if trained technicians are not accessible, the systems will not be sustainable.