NOVELTY - The system has a turbine rotor (6) which is operated to rotate about an elongate shaft (4) as fluid in a pipeline acts on rotor. An electrical generator arrangement is provided by a first portion having a magnet and a second portion having a winding (14) where a portion is mounted to rotor and the other portion is mounted to a stator element (13) that is positioned adjacent the rotor. Housing (24,25) is provided by two modules that are releasably attached to each other such that the modules are partly separated from each other to permit access to the rotor and the generator system.    USE - Power generation system to generate electricity from fluid flowing in pipeline.    ADVANTAGE - A simple, compact, modular turbine and potential hydroelectric power generation system is provided which gives good energy efficiency. The in-pipe turbine and hydro-electric power generation system is adapted to a variety of hydraulic conditions and head heights. As the system is installed easily in an existing pipeline with flanged ends on the system which couple with the existing pipeline, the need for a dam, weir or separate man-made water source is eliminated. Hence a reduction in the land required for hydroelectric power generation, low/zero environmental impact is obtained since there is no flooding or deforestation. As there is no relocation or rehabilitation, a reduced carbon footprint due to a reduction in the construction requirement is obtained. The system is easy to maintain without need for any specific device as the inlet guide vane and outlet stay vanes are removed and repaired or replaced easily from the casing. As the system contains only a single moving module, the shaft is stationery and the system is made easy for manufacturing, assembly, installing and maintenance. As a separate power house is not needed for the system, the civil construction and land availability causing minimum environmental impact is reduced. The arrangement of power generation system is more easily approved by a local government or authority since the system is not provided with a negative environmental impact on the environment.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a power generation arrangement; and    (2) a method for installing a power generation arrangement.    DESCRIPTION OF DRAWING(S) - The drawings show a cross-sectional plan view of portion of a power generation system and a perspective view of power generation system with horizontal split generator housing.    Elongate shaft (4)    Turbine rotor (6)    Stator element (13)    Winding (14)    Housing (24,25)