Perth Basin (varying % interest)

"Green Rock Energy, in conjunction with UWA, is preparing for the development of Australia's first commercial geothermal powered heating and air-conditioning unit at one of three commercial buildings in the Perth Metropolitan area."

Green Rock Energy holds 16 Geothermal Exploration Permits (GEPs) in Western Australia.

In the North Perth Basin where temperatures are the highest, there is geothermal potential for electricity production to be fed into the nearby power grid. In the Central Perth Basin which includes the Perth Metropolitan area, the focus will be on direct heat uses including air-conditioning and desalination of water, which displace electricity as their energy source.  

Location 

The Perth Basin is a 1,000 km long geological rift containing sediments up to 15 kms deep. Rifting ceased there in the Cretaceous age about 100 million years ago.  It contains thick sequences of permeable aquifers containing hot geothermal water with sufficient temperature and water flow capacity at depths considered to be economic for electricity generation.

The Perth Metropolitan Project

Green Rock Energy, in conjunction with The University of Western Australia, is preparing for the development of Australia's first commercial geothermal powered heating and air-conditioning unit at one of three commercial buildings in the Perth Metropolitan area. The geothermal energy will be the direct heat source which will replace conventional air-conditioners and their associated large scale electrical and natural gas consumption.

The Company is working towards the second half of 2010 with the commissioning of the commercial unit in 2011, making this the first commercial geothermal energy project operating in Australia outside the current small power plant at Innamincka.

Hot Dry Rocks Pty Ltd, a leading Australian geothermal consulting company, estimated that GEP 1 , covering 143 sq kms , contains Inferred Geothermal Resources of 30,000 PJ of storred heat (equivalent to 950,000 MWth yrs) for the purpose of a district cooling project. This is more than sufficient to supply the energy requirements of many direct heat projects in the Perth Metropolitan area including district heating, water desalination and purification of waste water by distillation.

With success of the Perth Urban Project the Company intends to replicate the concept in and around the city of Perth and at the Alkimos development to supply air-conditioning and heating needs of the other major energy users. This includes hospitals, shopping centres, data centres, industrial estates and a high density residential development of 30,000 people planned at Stirling. The Company plans to assess the geothermal potential of its Alkimos Permit whichy the developer Delfin Lend Lease hopes to be carbon-neutral.

In 2010 the WA Government granted Green Rock Energy $145,000 towards drilling two 500 metre deep exploratory holes in its Alkimos permit.This drilling will be used to confirm the heat flows and subsurface geology at the Alkimos development site.

Activities

Work carried out in relation to GEP 1 has included: evaluation of existing seismic drilling data; compilation of temperature measurements taken in the nearest petroleum wells and deep water bores; completion of gravity survey near the proposed well sites in the main University campus to confirm sub-surface geology; measurement of temperatures in a number of deep water bores and drilling of a 208 metre deep hole at the UWA campus in which the temperature profile was measured to confirm heat flow and estimate temperatures at depth and a vertical seismic profile was recorded to confirm the sub-surface geology.

In the northern Perth Basin the Company's six new Permits coincide with oil and gas producing areas, infrastructure and power lines. Our aim is to target hot water trapped underground rather than dry hot rocks.This region has been shown by an independent analysis commissioned by Western Australia's Department of Mines and Petroleum to have the Perth Basin's highest heat flows. This analysis, together with further heat flow studies commissioned by the Company using other data from our Permit areas, has further enhanced the Company's assessment of the geothermal energy prospectivity of the Permits. These surface heat flows determined from petroleum wells in the area have an average value of 95 mW/m and confirms the potential for sufficient temperatures in our Permit application areas at suitable depths for electricity generation. We will now direct our attentioin to locating areas where we can maximise the geothermal water flow rate from existing reserviors.

Objective - Perth Urban Project

Green Rock Energy is planning a 'proof of concept' project on the University of Western Australia (UWA) campus at Crawley 5 kms SW of the Perth CBD. The project will consist of two wells to approx. 3,000 metres and system flow testing. If commercial flow rates and temperatures are achieved, Green Rock will install an absorbtion chiller to supply base load chilled water for the campus reticulated chilling system. Supply of hot water and electricity may also be considered. Agreements are in place with UWA, including the pricing of geothermal energy at the full cost of the displaced retail-priced electricity. Total project cost including purchase, installation and hook-up of the absorbtion chiller is budgeted at $20.8 million.

Planning and approvals have commenced with the aim of commencing drilling in the first half of 2011.

Green Rock Energy has been offered a $7.0 million grant for the project (on a $ for $ basis) from the Commonwealth Government. The Company considers that a succesful first well will give a very high level of confidence that the second well and system flow will be commercial.

 

Using hot geothermal water to cool commercial buildings

By replacing a Conventional Chiller that uses electric energy with an Absorption Chiller using geothermal energy, large commercial buildings, including universities, hospitals, hotels, airports, data centres and shopping centres, can be air-conditioned using hot geothermal water as the principal power source.

Conventional Chiller versus Absorption Chiller

The air-conditioning units of commercial buildings conventionally use an electrical driven compression chiller (or refrigerator) to produce chilled water which in turn is used to cool the air.  An Absorption Chiller, using geothermal energy as the principal power source, is an environmentally friendly alternative to conventional compression chillers.  A comparison of the two processes is shown graphically below.

Air Chiller Diagram

 A)  Conventional Chiller
  1. High pressure vaporised, or gaseous, refrigerant flows to a Condenser where it is condensed to a liquid and the heat generated in the process rejected to the atmosphere.
  2.  The liquid refrigerant then flows through an expansion valve and depressurises in the Evaporator where it evaporates by absorbing heat which provides the cooling effect.
  3. The low pressure vaporised, or gaseous refrigerant flows into an Compressor where electrical energy is used to compress the refrigerant.

B)  Absorption Chiller 
  1.  Vaporised, or gaseous, refrigerant flows to a Condenser where it is condensed to a liquid and the heat generated in the process rejected to the atmosphere.
  2. The liquid refrigerant then flows through an expansion valve and depressurises in the Evaporator where it evaporates by absorbing heat which provides the cooling effect.
  3. The low pressure vaporised, or gaseous refrigerant flows into an Absorber where it is absorbed by a liquid absorbent to form a combined liquid refrigerant/absorbent.
  4. The combined liquid refrigerant / absorbent is pumped to a higher operating pressure Generator where geothermal energy is used to separate the vaporised, or gaseous refrigerant from the absorbent.  The vaporised refrigerant flows to a Condenser.  Having separated from the refrigerant, the liquid absorbent flows back into the Absorber. 

The cooling process

When a liquid evaporates, or boils into a gaseous state, it uses a significant amount of energy or heat.  This energy, or heat, is extracted from the surrounding environment.

Both forms of chillers, Conventional Compression Chillers and Absorption Chillers, evaporate a liquid refrigerant to produce chilled water which in turn is used to cool the air.  The difference between the two chillers is how they convert the refrigerant from the gaseous state back to a liquid.

A Conventional Chiller converts the gaseous refrigerant back to a liquid by using a compressor to increase the pressure on the gas and then condenses the high pressure gas to a liquid using a heat exchanger, or condenser.  The compressor is the main consumer of energy - in this case electrical energy.

An Absorption Chiller absorbs the gaseous refrigerant into a liquid absorbent and the combined refrigerant and absorbent are pumped to a high operating pressure generator where thermal energy (hot water) separates the gaseous refrigerant from the absorbent which then condenses to a liquid using a similar heat exchanger, or condensor, as does a Conventional Chiller.  The generator is the main consumer of energy - in this case thermal energy.

Energy usage

A Conventional Chiller raises the pressure of a vaporised refrigerant whereas an Absorption Chiller raises the pressure of a liquid absorption/refrigerant solution, the latter requiring an order of magnitude less electric power.

The Absorption Chiller uses an external thermal (geothermal) energy source to separate the pressurised and vaporised refrigerant from the absorbent.

One geothermal production well, plus one injection well, could provide enough geothermal energy to air-condition a large commercial building.

 

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