Economic analysis of domestic solar still in the climate of Costa Rica

Abstract

In many communities of the developing countries, including Costa Rica and especially in coastal areas, there exists s shortage of potable water. Taking into account the fact that transportation/distribution of potable water is expensive for these communities and most of these places are blessed with good sunshine, one domestic solar still per family could help in getting fresh water—at least for drinking purposes (say 10 1 per day). Although the design, construction and technical results of three small-scale solar stills studied by the author have been presented in local technical journals, these results are mentioned briefly and are used for the estimation of total quantity of water distilled per year in three different climates of Costa Rica. In one study, estimation of rain water collected over the glass cover of a solar still has also been made as this can be considered as drinkable water where potable water is not available. In the present work, economic analysis of these stills have been made at these places in Costa Rica—not to show that cost of water produced from these stills is expensive compared to a conventional centralised system (including subsidies), but to see how expensive it is. Comparisons have been made with distilled water produced from a domestic electric still. It has been found that the cost of water produced from the solar still is 15–30 times more expensive than sold presently by the centralised system, however, it is far cheaper than produced by the electric still. Another objective of this study was to produce a basis for the construction of various small stills or one big plant for one community, e.g. Island Chira, lacking potable water. Finally, some social benefits of these types of installations at remote places, even though they are expensive, are mentioned.