Closed Loop Geothermal Systems

TECHNOLOGY

Good Water Energy uses the single, closed loop well system that can be used instead of the traditional and environmentally damaging twin well system, that was also previously unsuccessful in Australia.

  • Can be implemented in any geothermal heat reservoir, irrespective of the presence of groundwater with a sufficient, inherent flow rate.
  • Can be located where there is a demand for electricity and desalinated water, or where there are existing distribution networks.
  • Only one well required for each producing unit.
  • No extraction or re-injection of potentially toxic geothermal groundwater.
  • Due to casing, scale deposits cannot form in geothermal groundwater reservoirs.
  • No depletion of geothermal groundwater reservoirs.
  • Considerably longer casing and well life.
  • Lower energy requirements from surface pumps.
  • No requirement for stimulation or fracking.
  • No downtime required for down hole pump service and replacement.
  • Easy replacement of production casing for upgrades.
  • No expensive steering of wells required (directional drilling).
  • Lower cost energy production.
Good Water Energy propose the single well system that circulates noncorrosive fluid (the working fluid) down a fully lined and isolated well by surface pumps, to be heated by the ground heat source (the geothermal heat reservoir).

The well is classified as a coaxial design, closed loop downhole heat exchanger with an insulated inner tube for the hot ascending working fluid and a conductive outer casing to allow maximum heat transfer from the geothermal heat reservoir to the cooler descending working fluid.

All surface piping and equipment is not damaged by corrosive and potentially toxic water as the geothermal groundwater reservoir is kept isolated from the well, and only thermal energy (heat transfer) flows towards the well.

Using the single well system, no fluid is extracted from or injected into the geothermal reservoir and no fracking is required for communication between the two wells. Heat only transfers from the geothermal reservoir and is transferred to the surface by a controlled fluid that is isolated from the reservoir within corrosion resistant well casing. Pumping is from the surface and no surface plant equipment is exposed to corrosive saline groundwater. Organic Rankine Cycle fluid is heated by surface heat exchangers to drive turbines that in turn drive electricity generators.

Waste heat is taken from the turbine exhausts and used to boil seawater in Multi Effect Distillation (MED) desalination plants. Good Water Energy intends to establish salt management systems for the harvesting of high-quality sea salt to reduce or even totally eliminate salt brine return to the ocean. Where possible and approved, the company will install salt evaporation ponds to produce sea salt and other minerals such as lithium and other elements which may also be extracted during this process.
This methodology minimises the environmental impact and lengthens the lifetime of the well system.

With a single well system there is no reliance on natural or stimulated permeability in the geothermal groundwater reservoir to produce a suitable groundwater flow to the producing well.

This has historically been the main problem experienced with all conventional dual well geothermal projects in Australia to date. The single well system can therefore be implemented in any geothermal heat reservoir, irrespective of the presence of groundwater with a sufficient, inherent flow rate.

This means the project can be located at the marketplace where there is a demand for electricity and desalinated water, where there are existing distribution networks, and where there are other source materials such as seawater

GWE - closed well technology