The work presented in this thesis explored the potential of using a mix of renewable energy resources (hybrid power systems, HPSs) to generate electricity that meets power needs of mobile base stations at rural areas in Nigeria. The study was based on theoretical mathematical modeling and simulation using the hybrid optimization model for electric renewables (HOMER) software. A sample of eight hypothetical off-grid remote telecommunication base station (BTS) sites at various geographical locations in Nigeria was used for the study. These locations include: Abaji (Abuja, FCT), Nkanu-West (Enugu), Ikwerre (Rivers), Nembe (Bayelsa), Mopa-Muro (Kogi), Kauru (Kaduna), Guzamala (Borno), and Tureta (Sokoto), and were selected to reflect the various climatic conditions in Nigeria. Eight different combinations (HPS options) of four energy resources [small-hydro power (SHP), wind turbine generator, solar photovoltaic (SPV) and diesel generator (DG)] were studied and compared for each of the eight selected BTS sites. These are: Hybrid (Solar, Wind & Hydro) + DG; Hybrid (Solar & Hydro) + DG; Hybrid (Wind & Hydro) + DG; Hydro only + DG; Hybrid (Solar & Wind) + DG; Solar only + DG; Wind only + DG. Total Net Present Cost (NPC) and total CO2 generated are used as indices for measuring the optimization level of each energy solution, and the option with the highest optimization value is considered to be the best energy solution for that base station site. The quantitative results of the study (as reported here) show that the hybrid power system can be more cost-effective and environmentally friendly in providing energy to BTS sites than diesel generators. The results also show that there is no general least-cost option for powering GSM base station sites at different locations. It all depends on climatic conditions and available renewable energy resources. A major contribution of this work is the demonstration (by these results) that it is possible to develop an optimized energy map for appropriate locations of GSM Base Station sites in Nigeria, both as a design guide for network operators and for the formulation of energy use policies by the national telecommunications regulatory authority (the NCC). One of such policies could be the requirement that any network operator intending to site a base station in any location should first produce an optimized energy feasibility study of the location before an approval would be granted.