This proposal covers a large area extending from Daylesford in the north to the Bellarine Peninsula and Surf Coast Shire Council in the south. Notably, this area contains the major industrial centre of Geelong, and the western half of suburban Melbourne, as well as some parts of the Otway Basin. Currently, Greenearth Energy Ltd is the permit owner for this area.
Although currently in the ‘Proof of Concept’ stage, the project has received $12m of Federal and State Government funding for initial work to confirm the extent and quality of HSAs at the allocated GEP sites, with a further $20m allocated by the Victorian Government towards the construction and demonstration of a $64m, 12MW geothermal power plant.
The Proof of Concept stage is planned to commence during in the second half of 2010 with the drilling of the 4,000m deep Geelong Geothermal Production Well No. 1, followed by a second injection well upon successful completion of the first one.
While significant concerns have been raised about the company’s handling of planning processes and community consultation to date, the proposed project location nine kilometres north-west of the brown coal fired power station at Anglesea has been selected on the basis that it targets the hottest and thickest section of a HSA geothermal reservoir formation of greater than 1,000 metre thickness. Many concerns related to what appeared to be a pre-emptive public consultation process, which alienated many people who may otherwise have been supportive of the project.
As a result of concerns, the proponent has changed some aspects of how it will do its drilling. A deviated well design has been developed and directional drilling techniques will be employed to minimise the number of drilling pads and maximise the length of geothermal reservoir which is intersected. A modest deviation of 15 degrees from the vertical incline at the 1,000 metre level can achieve the adequate separation within the HSA reservoir of production and injection wells of approximately 1,500 metres at a vertical depth of 4,000 metres. This separation is necessary to regulate geothermal fluid flow and reservoir pressures.
This geothermal well couplet is designed to demonstrate the capability of producing and injecting geothermal fluid at suitable temperature as well as monitor the flow rate for geothermal power production. Depending on the success of the first stage, long term flow testing is planned for the first half of 2012 in order to enhance the development of a robust understanding of the geothermal reservoir for future commercial use. A further two geothermal wells (one production and one injection) will be created from the same drilling pad, with two geothermal well couplets from the single well pad to tap approximately 3 to 4 km2 of reservoir area.
Individual drilling pads will be utilised to locate the site for 12MWe modular geothermal power plants. This modular scale approach is intended as a model for potential replication across the Geelong Geothermal Power Project HSA resource as a cost effective method of developing the full target reservoir to its potential 140MWe Net. The culmination of these developments is detailed in the Sinclair Knight Merz pre-feasibility study of the Geelong Geothermal Power Project. It consists of 12 modular 12MW plants being developed over a (yet to be determined) period of time across the HSA reservoir, to potentially deliver 140MW of substantial base load emissions free electricity along with significant carbon displacement potential.
Further information (from the proponent) can be found here.