The Euripus tidal stream at Halkida/Greece: a practical, inexpensive approach in assessing the hydrokinetic renewable energy from field measurements in a tidal channel

In the Euripus channel, we assess the hydrokinetic tidal resource at the narrowest constriction which is in the city of Halkida at the Old Bridge. This is accomplished by combining data from (a) several ADCP (Acoustic Doppler Current Profiler) cross-channel snapshot transects at the Old Bridge and (b) a 2-month current meter record obtained at 1.5 m off the bottom at the edge of the cross section at the New Bridge, which is a $$\sim $$∼fourfold wider constriction with lower tidal velocities compared to the Old Bridge. A linear relationship exists between the along-channel velocity at the current meter site and the maximum of the along-channel velocity on the cross section at the Old Bridge. We can, therefore, determine the cross-channel distributions of the along-channel velocity at the Old Bridge during the 2-month period of the current meter record. We examine the use of a 4-m-diameter turbine, suitable to the space limitations at the Old Bridge. This turbine functions for flow velocity values higher than $$\sim $$∼50 cm/s and with a nearly constant efficiency of $$\sim $$∼40–45 % for flow velocity higher than 50 cm/s; a constant 45 % is achieved for all velocity values higher than 150 cm/s. This machine yields an annual energy of $$\sim $$∼28.6 MWh, out of an existing $$\sim $$∼71.5 MWh for its aperture when there is zero efficiency loss. This amount of energy is not enough for wide-scale applications but it covers the needs of an exhibition place for tourists visiting Halkida, which was the first question posed in the beginning of this project.