A review of the UK and British Channel Islands practical tidal stream energy resource

This review provides a critical, multi-faceted assessment of the practical contribution tidal stream energy can make to the UK and British Channel Islands future energy mix. Evidence is presented that broadly supports the latest national-scale practical resource estimate, of 34 TWh/year, equivalent to 11% of the UK’s current annual electricity demand. The size of the practical resource depends in part on the economic competitiveness of projects. In the UK, 124 MW of prospective tidal stream capacity is currently eligible to bid for subsidy support (MeyGen 1C, 80 MW; PTEC, 30 MW; and Morlais, 14 MW). It is estimated that the installation of this 124 MW would serve to drive down the levelized cost of energy (LCoE), through learning, from its current level of around 240 £ / MWh to below 150 £ / MWh , based on a mid-range technology learning rate of 17%. Doing so would make tidal stream cost competitive with technologies such as combined cycle gas turbines, biomass and anaerobic digestion. Installing this 124 MW by 2031 would put tidal stream on a trajectory to install the estimated 11.5 GW needed to generate 34 TWh/year by 2050. The cyclic, predictable nature of tidal stream power shows potential to provide additional, whole-system cost benefits. These include reductions in balancing expenditure that are not considered in conventional LCoE estimates. The practical resource is also dependent on environmental constraints. To date, no collisions between animals and turbines have been detected, and only small changes in habitat have been measured. The impacts of large arrays on stratification and predator–prey interaction are projected to be an order of magnitude less than those from climate change, highlighting opportunities for risk retirement. Ongoing field measurements will be important as arrays scale up, given the uncertainty in some environmental and ecological impact models. Based on the findings presented in this review, we recommend that an updated national-scale practical resource study is undertaken that implements high-fidelity, site-specific modelling, with improved model validation from the wide range of field measurements that are now available from the major sites. Quantifying the sensitivity of the practical resource to constraints will be important to establish opportunities for constraint retirement. Quantification of whole-system benefits is necessary to fully understand the value of tidal stream in the energy system.

Potential Study of Tidal Stream Turbine Farm at Toyapakeh Strait, Bali

In 2015, Bali Province is mandated by ESDM ministry to become the National Region of Clean Energy, promoting efforts to explore new source of electricity namely tidal stream energy. Previous works have demonstrated that Toyapakeh Strait contains a promising tidal stream resource, with a high stream in a long period. In this study, hydrodynamic modelling and power production analysis is conducted to evaluate this potential with an aim to meet energy demand of Tiga Nusa Cluster Islands. Twenty-one Gen5 KHPS turbines are employed in this study, at an optimized location, 8.72°S, 115.44°E, which contains the highest energy potential. Financial analysis, with 25-year return period of investment and 3.60% interest rate, resulting levelized cost of energy (LCOE) of Rp 6,100.kWh-1. This value is higher than the national and regional selling nominal, in other word the energy cost of tidal stream turbine is relatively high in this location. Nearly 46% of energy cost is spent for turbine fabrication, and from the sensitivity analysis, cutting half the turbine costs may reduce the price by Rp 1,400.kWh-1 while increasing the amount of installed turbine is less significant. Despite of the high prices, the study shows that Toyapakeh Strait holds a promising resource of tidal stream energy.

The Fluid Mechanics of Tidal Stream Energy Conversion

Placing mechanical devices into fast-moving tidal streams to generate clean and predictable electricity is a developing technology. This review covers the fundamental fluid mechanics of this application, which is important for understanding how such devices work and how they interact with the tidal stream resource. We focus on how tidal stream turbines and energy generation are modeled analytically, numerically, and experimentally. Owing to the nature of the problem, our review is split into different scales—from turbine to array and regional—and we examine each in turn.