This research focuses on proposing and evaluating an optimized hybrid system of wind and tidal turbines operating as a renewable energy generating unit in New Zealand. Literature review indicates increasing worldwide investment in offshore renewable energy in recent years. Offshore energy shows a high potential as an alternative energy generation solution to that of fossil fuels. Using the capacities of wind and tidal power in renewable technologies would be a suitable alternative for fossil fuels and would help prevent their detrimental effects on the environment. It is a cost-effective procedure for the power generation sector to maximize these renewables as a hybrid system. At the design phase, turbine types appropriate to environmental conditions for an area with high wind speed and tidal flow need to be considered. When selecting which turbines should be used, horizontal or vertical axis, number and length of blades, and optimized rotational speed are all important to get maximum capacity from either the wind or tidal energy for the hybrid system. Comprehensive simulation models of the hybrid system are now being set up, using several available commercial software packages such as QBlade, Simulink, and RETScreen. Several different parameters will be required for these simulation models to run in order to test performance, capacity and efficiency of the proposed hybrid system. To decide which regions are suitable for the hybrid system, it will be necessary to analyze available wind and tide records from NIWA, and online databases such as GLOBAL ATLAS. This next phase of research will aim to create optimized scenarios for the hybrid model by considering the effect of wind and water speed on performance. After deciding which region and scenarios are suitable, it will also be necessary to evaluate the costs and returns of a hybrid system. This final phase will be performed using the RETScreen simulation model.

This paper evaluates the feasibility of using a hybrid system consisting of wind and tidal turbines connected to a microgrid for power supply to coastal communities that are isolated from a main supply grid. The case study is Stewart Island, where the cost of electricity, provided by a central diesel power station, is higher than the grid network in New Zealand. Local residents believe that reducing the consumption of diesel and having a renewable source of electricity generation are two of the island’s highest priorities. Merging a tidal energy source (predictable) with wind (unpredictable) and diesel (back-up), through a microgrid, may be a way to increase reliability and decrease the cost of generation. Several off-grid configurations are simulated using HOMER and WRPLOT software. Using two wind and four tidal turbines, plus one diesel generator for back-up, is the best design in terms of lower greenhouse gas emissions, higher renewable fraction, and reduced net present cost.

This paper evaluates supply to coastal communities that are isolated from a main supply grid compared to current used diesel station. The case study is Stewart Island, where the electricity is provided by a distribution network powered by up to ve diesel generators at a central diesel power station. Local residents believe that reducing the consumption of diesel and having a renewable source of electricity generation are two of the island's highest priorities. Merging a tidal energy source (predictable) with wind (unpredictable) and diesel (back-up), through a microgrid, may be a way to increase reliability and decrease the amount of pollutants. Using two wind and four tidal turbines, plus one diesel generator for back-up, is the best design in terms of lower greenhouse gas emissions, higher renewable fraction, and reduced net present cost. This con guration is simulated and compared with diesel generators system using HOMER PROro software. The results enable to analyse the amount of emissions for both scenarios.

This paper aims to design an integrated offshore structure capable of supporting a hybrid assembly of one wind plus two tidal turbines. The monopile has been found to be a suitable foundation type as the most inexpensive solution in water depths of less than 30 m. The Cook Strait in New Zealand is an ideal location for wind and tidal renewable energy sources due to its strong winds and tidal currents. Finite element analysis was performed to determine the displacement of the structure for different types of soils using OPTUM G3. After that, a macro-element model for soil was represented, considering the monopile as a Euler–Bernoulli beam model. The results enable the finding of optimum dimensions of monopiles with allowable tilt and deflection. Based on this, the diameter, thickness, and length of the monopile can be 6, 0.083, and 60 m, respectively. The maximum load occurs in extreme wind load scenarios when wind and waves move in same direction.

The Cook Strait in New Zealand is an ideal location for wind and tidal renewable sources of energy due to its strong winds and tidal currents. The integration of both technologies can help to avoid the detrimental effects of fossil fuels and to reduce the cost of electricity. Although tidal renewable sources have not been used for electricity generation in New Zealand, a recent investigation, using the MetOcean model, has identified Terawhiti in Cook Strait as a superior location for generating tidal power. This paper investigates three different configurations of wind, tidal, and wind plus tidal sources to evaluate tidal potential. Several simulations have been conducted to design a DC-linked microgrid for electricity generation in Cook Strait using HOMER Pro, RETScreen, and WRPLOT software. The results show that Terawhiti, in Cook Strait, is suitable for an offshore wind farm to supply electricity to the grid, considering the higher renewable fraction and the lower net present cost in comparison with those using only tidal turbines or using both wind and tidal turbines.