Powering Rottnest Island
Rottnest Island is a unique, natural wonderland off the coast of Fremantle. The provision of water and energy are not often thought of, however the behind the scenes of how the Island ticks is quite complex and it is a balancing act all visitors play a part in.
Rottnest Island is located 18kms off the coast of Fremantle. With that being the case, the Island must source its own water and energy for consumption and dispose of litter and wastewater in a self-sufficient manner.
The Rottnest Island wind energy project has been evolving from as far back as 1979. Two initial wind turbines were erected on Forbes Hill, however due to difficulties they were removed in the 1990's and the lone wind turbine now stands on Mt Herschel. This current wind turbine, installed in December 2004, produces around 30% of the Islands’ power needs. At maximum capability, it is able to produce up to 37% of the Island's power. Through the advancement of technology, the Island is looking towards a target of 45% of its energy being produced by renewable sources with solar power soon to be implemented. The remainder of power is supplied through a generation plant with low-load diesel and standard diesel generators.
Due to a trending decline in rainfall on the Island and a decreasing groundwater supply, a desalination plant was installed to provide the majority of water, rather than through extraction of groundwater bores. Since 2012, further investment has been made in the upgrade of water utilities on the Island to create a greater capacity in desalination and waste water reuse. As a result, groundwater abstraction is now capped at 20,000kL per year, a significant reduction from the average of ~33,000kL per year abstracted since 2007.
The desalination plant and wind turbine combined also save approximately 430 000 litres of diesel per year and reduces greenhouse gases by around 1100 tons per year.
Wastewater from toilets, showers and other domestic drains is treated at the on-island Waste Water Treatment Plant. The Plant currently uses a Cyclic Activated Sludge System (CASS) to break down the waste and will soon be upgraded and converted to a Membrane Bioreactor to allow improved and more consistent treated water quality. The plant will seek to recover ~65,000kL of waste water annually, which will be used for irrigation purposes on Rottnest Island, further reducing the requirement to undertake abstraction.
Rottnest Island has a coloured lid system for the waste bins located on the Island. These coloured bins allow waste to be separated and processed on the Island at the Transfer Station, ready to be transported to the mainland for correct disposal.
Please assist us by using less water, turning off the switches and disposing of litter correctly.