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, the Company holds nine GEPs which are held 100% by Green Rock Energy.
Of the four GEPs held in the Perth Metropolitan area, three are held 100% by Green Rock Energy and one is held jointly with the University of Western Australia (50% interest).
In the South Perth Basin (Collie area) Green Rock Energy hold three GEPs jointly with BHP Billiton Worsley Alumina in varying percentages.

There is geothermal potential in these areas for electricity production and direct use of the geothermal energy, 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. 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 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.

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

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.
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.
The low pressure vaporised, or gaseous refrigerant flows into an Compressor where electrical energy is used to compress the refrigerant.

B) Absorption Chiller

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.
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.
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.
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.