Quantitative and qualitative selection criteria are determined from the particular requirements of the end user. This paper describes a method to select which turbine architecture is most appropriate for a low-head pico hydro specification using quantitative and qualitative analyses of 13 turbine system architectures found in literature. Pico hydro turbines can be applied beyond these conventional application domains, for example at reduced heads, by using non-traditional components such as low speed generators. In the pico range, under 5kW, the requirements are often different to that of larger scale turbines and qualitative requirements become more influential. Turbine types suit specific ranges of head, flow rate and shaft speed and are categorised by specific speed. However, there are still more potential uses, for example in tidal range or tidal fence situations, although research for use in these methods are currently only in the initial stages with Computational Fluid Dynamics (CFD) simulations and scale modelling required to prove the validity. The inclined and horizontal turbines offer greatly reduced environmental effects and can be used in areas previously passed over because of delicate habitats. The submerged tidal stream device can operate in low flow velocities (1 m/s) that current devices are unable to. These new devices have the possibility to unlock a wide range of applications. The Archimedes Screw turbine currently has a variety of operational modes: inclined, horizontal or submerged. With further research for turbine operation alone required. Most existing design theory is for use as pump however there are many key differences between operation as a pump or turbine, such as the direction the water flows through the device. It has been found this new turbine device has a plethora of advantages over current existing devices, with the simplicity and robustness that has kept the pump in use for centuries acting in its favour. This is now an established turbine, being used in Europe since 1994. In recent times, it has seen a major revival in modern engineering, by reversing it for use as a turbine. The Archimedes pump is one of the oldest feats of engineering still being used today.
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