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Cost-effective solution for electric micro-grid in Rottnest Island

Moyo, Mondli (2017) Cost-effective solution for electric micro-grid in Rottnest Island. Honours thesis, Murdoch University.

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Microgrids are a relatively recent technology, but the concept has been around for a long time. Since the first power system built in 1881, power systems have experienced substantial changes leading to the current networks where all the electrical energy is produced in large plants that are heavily dependent on fossil fuels, hydro and sometimes nuclear power (Ernst 2014). Micro grids have always been in existence but the technology to implement them on a large scale has limited micro grids from flourishing.

Rottnest Island is a notable example of a place currently implementing the use of a hybrid micro-grid (HMG) on a large scale. Up until recently, the island was solely dependent on diesel generators for electricity, in 2004 a 600kW wind turbine was added to supplement the electricity energy produced by generators and offset some diesel fuel consumption. Due to the high costs of shipping diesel into the island, The Rottnest Island Authority (RIA) decided to upgrade the island’s electrical network by incorporating a 600-kW photovoltaic system into the network and upgrading the existing water treatment plant as the RIA had recorded increasing levels of salt levels in the island’s underground water.

This research evaluates multiple aspects of running the upgraded hybrid solar-wind-diesel micro-grid and how the levelised cost of electrical energy production can be reduced by using Homer software to analyse the island’s electrical load profile and using the data to assess every possible system combination. The current setup of the network is quite inefficient as there is excess power being produced which is then being sent to a dump load. The results have been conclusive in terms of finding better combinations that will not only increase the reliability of the HMG but also reduce the overall LCOE. Storage capabilities in the network would be advantageous not only in reducing the LCOE but also producing a high quality of power while also increasing the overall stability of the network.

Further simulations were conducted to include a theoretical load into the existing system. This was view as a theoretical thermal load that simulates the idea of hot water storage for the island. The thermal load was designed in a way that it would consume any excess energy being generated in the system to heat up water for later usage.

The conclusion has been that while the current HMG setup is functional and environmentally friendly, the LOCE of the overall network is high and impractical. For the current design of the microgrid, a lot of energy is wasted, which is energy that can be utilised by incorporating components such as storage devices or maybe utilising the already existing desalination plant to heat and store hot water. These components could help reduce the number of diesel generators used and utilises most of the electricity generated by the renewable energy sources.

Item Type: Thesis (Honours)
Murdoch Affiliation(s): School of Engineering and Information Technology
Supervisor(s): Arefi, Ali
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