Geothermal energy enabling desalination

Leader

Challenge

Western Australia (WA) is facing sustainability challenges with its water and energy resources however, there are plentiful supplies of brackish and saline water resources and geothermal energy, located across the state. The challenge is to identify desalination technologies that make it feasible to utilise the two resources.

Multi-effect desalination (MED)  is widely used in seawater desalination and in the chemical industry due to its low electrical energy consumption, low operation cost and high thermal efficiency. MED is a process that is suitable for use on a range of water types, including brackish and saline waters, and requires a thermal energy source to drive the distillation process. Typically MED has a recovery rate of 65% from a saline feedwater source and the brine can potentially reach concentrations of over 70,000mg/L total dissolved solids. Boosted MED can further increase recovery by recycling the outflowing heated fluid from the first stage back into the system.

Method 

Conduct a feasibility study for the implementation of geothermal desalination in the mid-west and north-west regions of WA, taking into account economic, technical and market factors. Identify geographical areas where the desalination could be best applied by accessing existing datasets available from the partners. Identify any potential blocks to implementation of geothermal desalination technologies that may exist in WA regulations and policies.

Outcomes

WA has eight sedimentary basins with onshore components that may provide suitable sources of geothermal energy. A desirable characteristic is temperature between 75-90ºC, which is needed in order for geothermal desalination to be competitive against alternative desalination methods such as reverse osmosis. Based on this and a number of other characteristics, the Perth, Carnarvon and Canning Basins are potential targets. The Canning and Carnarvon Basins have low density populations but local scale geothermal desalination may still be feasible.

A number of potential target towns/cities were identified and assessed for feasibility. Factors such as location to water source, future population predictions and current cost of water were taken into account for the case studies. An economic and engineering model was developed to estimate the potential cost of geothermal desalination in these locations. The findings indicate it is possible to produce water at a competitive price utilising geothermal energy resources and seawater. The use of the desalination is most feasible in locations of high water cost and a subsidy may be required in other locations. Implementation was sensitive to a range of cost factors, the most significant of which is the geothermal field development and well drilling cost.

Access to water resources in WA is limited by the regulations surrounding access to and abstraction of the resource. The management of water resources and the abstraction limits is managed by the Department of Water through the issue of licenses and permits. The limitation provided by the allocation and licensing process does not guarantee that water is available in times of drought, where additional restrictions may be applied by the Department to minimise long term damage to the water resource.

Future Direction

The next step is to conduct a field trial of a full-scale boosted MED demonstration plant at one of the target sites. There is also the potential for future development and planning of geothermal desalination opportunities, particularly in relation to regional development needs, for example through the WA Government’s Pilbara Cities Initiative.

Partners

Lieb partner logos


 

Total Value: $342,596 (cash and in-kind contributions)

Principal Investigator: Professor Klaus Regenauer-Lieb

Title: Pre-feasibility investigation of water and energy options utilising geothermal energy, multi-effect distillation and reverse osmosis

Length: 20 months

Personnel: 10 collaborators contributing 1.0 FTE

Related Project: Development of a novel low grade heat driven desalination technology

Further Information 

FR4 UWA Geothermal Summary Poster updated

Project Summary Poster – geothermal opportunities

WP-Backgrounds Lite by InoPlugs Web Design and Juwelier Schönmann 1010 Wien