Cooling of high temperature bore water using thermoelectric generated power

Finnerty, Sean (2018) Cooling of high temperature bore water using thermoelectric generated power. [USQ Project]


This report investigates the issues surrounding high-temperature bore water from the Great Artesian Basin (GAB) and seeks to find feasible and economically viable solutions. The report presents methods of recovering the heat energy from bore water as well as the history of power generation from water and geothermal energy in Australia. The report then presents options for using some of the recovered energy to cool the bore water to an acceptable level of 45o C while protecting equipment from corrosion, environment and vandalism.

The GAB underlies 22% of the Australian mainland with an area of 1.7 million square kilometres; making it one of the largest groundwater basins in the world. The GAB is an essential resource to large areas of inland Australia and the Aboriginal peoples who used the GAB natural springs for thousands of years before European settlement. Use of this resource opened the way for agricultural and pastoral expansion to the west of the Great Dividing Range and away from rivers. Today, it provides the only reliable source of water for a number of remote regional towns as well as providing water for irrigation and stock feed.

Water within the GAB is heated by radioactive decay and previous volcanic activity leading to temperatures of up to 130o C at depth and bore outflow temperatures above 90o C. Early bores flowed freely into bore drains or open ponds where the water cooled in the open air. While cheap and effective at cooling the water, a great deal of the water was lost to evaporation and seepage, and in 1999 the Australian Government began funding for the Great Artesian Basin Sustainability Initiative (GABSI) to assist with capping uncontrolled bores and replace bore drains with pipe. This created a new problem as the hot water damaged equipment and impacted on the cost, design and materials used for the delivery system.

While the hot water contained within the GAB has excellent potential for creating energy, it is often located a great distance from the power grid or any large industrial customers. This report explores possibilities of small scale power generation systems that can be used locally to power systems for cooling the bore water before entering the distribution system. The report looks at systems currently in place and the history of geothermal energy as well as the possibility of producing electricity using thermoelectric power generation.

The environment in areas of the GAB is harsh with wind, dust, high temperatures and low humidity. The bore water can also be corrosive with lower pH and dissolved salts leading to corrosion, scaling and fouling of equipment. Hence, any proposals need to be robust and easily serviceable and the designs must be protected from the possibility of damage by vandalism or wildlife.

The report proposes two methods of cooling water using power generated by thermoelectric generators (TEGs). The first design is an air cooled system that uses power from the TEGs to drive cooling fans that circulate air over cooling spirals. The system is robust and self-sufficient; however suffers from low cooling rates and a need for multi-stage cooling or the addition of cooling vanes for high temperature bore water. This system is the preferred option for remote, low flow applications.

The second option is a modified cooling tower design. Cooling towers are highly efficient and effective and with some modification can be run using TEG derived power. The commercially available systems require pumps that would require more power than can be reasonably produced from TEG power alone. However the system could be modified to run at a lower capacity and power requirement. Additionally, the system requires regular monitoring and maintenance to ensure continuous efficient operation. This system is the recommended option for towns or settlements that require higher flow rate and have the personnel to maintain the equipment.

Protection from the potentially corrosive water can be supplied by a combination of coatings and cathodic protection. This ensures efficient long term operation of the equipment. Equipment can be further protected from the environment using protective covers or enclosures.

TEG assisted cooling is a viable option for the cooling of high temperature bore water. However the output can be quite low and relies on the temperature differential between the water and air. The advantage of these systems is that the power produced is continuous and sustainable and with appropriate design is capable of cooling the bore water to acceptable levels.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Wandel, Andrew
Qualification: Bachelor of Engineering (Honours) (Civil)
Date Deposited: 15 Sep 2021 05:23
Last Modified: 29 Jun 2023 01:32

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