Diesel power plants use diesel engines as prime movers powered mainly by heavy fuel oil or industrial diesel oil and with potential for conversion to gas engines or dual fuel engines. The global concerns over prices of diesel and heavy fuel oil and energy related greenhouse gas emissions have created demand for natural gas as an alternative fuel for power generation by diesel power stations. This study involved a performance analysis of an operating diesel power plant and its potential conversion to dual fuel engine power plant. Dual fuel engines have reduced fuel costs and greenhouse gas emissions since natural gas is the cleanest fossil fuel. For a conventional diesel engine to run on diesel, the fuel injection system is modified to handle gas and a mixture of gas and diesel. Other modifications are the introduction of an electronic control unit, reduction in air fuel ratio, installation of a fuel mixer, and reduction of compression ratio. The conversion requires provision for natural gas storage facilities and supply system which were introduced in the proposed design modification. The study showed that dual fuel engine power plants have better performance indicators like lower specific fuel consumption, higher indicated and brake thermal efficiency, cheaper power produced, less emissions per unit power and thus reduced environmental impact. Conversion to dual fuel engines will reduce the cost of electricity generation, reduce emissions particularly Sulphur dioxide while accommodating fuel flexibility like use of biofuel to substitute diesel.