Assessment of Global Solar Radiation over Rwanda

Abstract

This paper aims to estimating the global solar radiation in Rwanda. We mainly treated the particular case of Kigali where meteorological data records (sunshine duration, temperature, pressure and humidity) over a period of 20 years (1974 to 1993) are available. As solar radiation data are not available in Rwanda, meteorological models (MRM) were applied and sunshine duration measurements played a particular role. The MRM basedresults were validated by satellite datasets measurements done over a 10-year period (1984 to 1993); and a good agreement between these two approaches was confirmed. Finally and referring to the five representative sites, a recommendable solar data information per region was adopted. We found out that the monthly averaged global solar radiation varies between about 4.3 to 5.2 kWh / m2. day over Rwanda, a hilly and mountainous tropical country.Index Terms--radiation, meteorological, sunshine, transmittance I. BASIC INFORMATION AND PROJECTIONIn Rwanda, energy sector remains characterized by a traditional behavior and a limited investment in modern options. For instance and among others, the lampion is still a main source [64 %] of energy lighting while the firewood covers the most [85%] part of the cooking demand.Within the 2003 year access rate to electricity was only about 5% while future electricity demand [households, public services and industrial sector] is obviously expected to be high according to some following key indicators related to the urbanization growth, the industry progress and the environmental concern.According to the last census organized in Rwanda in 2002 by the statistic department in the ministry of finance and economy, it was found out that 83 % of populations were rural against 95 % in 1991. The industry and the services are contributing more and more to the GDP, respectively 19 and 36 % within 2002. There is also a great need in deepening commitment to reducing deforestation [decrease of forest cover of about 70% between 1958 and 1996] by among others promoting the use of electricity instead of charcoal or firewood.Therefore meeting with such a high demand for future requires sufficient production. The population pressure will lead to at least 10 millions of inhabitants by 2012 and the ambitious electricity access rate of 23% being a target, this will be achieved through a capacity of 1384 GWh [about 384 MW] against 235GWh [65MW] available today. Such challenges can be addressed through an important investment in a scenario of combining different sources of energy and technologies as follows. 50% from domestic hydropower [192MW], 10% by imported hydropower [38MW], 26 % from diesel and Kivu lake methane gas generators [100MW], 7 % from solar [27MW] and also 7% by a contribution from nuclear mini-generators.Wind power alternative in Rwanda being very limited, diesel expensive as imported, methane gas an important source of CO2 emission mainly due to the composition of the crude gases extracted from the lake, nuclear option remaining a political concern, the solar energ...

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