FIELD OF THE INVENTION

This invention provides a method of producing energy from a greenhouse gas including carbon dioxide and a system for producing energy from a greenhouse gas including carbon dioxide. In particular, this invention relates to a method of producing energy which utilises predominantly carbon dioxide to provide or supplement energy to existing power generating systems. In particular, this invention relates to a method and system which utilises a greenhouse gas including carbon dioxide in a manner which is advantageous to the environment.

BACKGROUND

It should be understood that any discussion of the background art throughout this specification should in no way be considered as an admission that such background is prior art nor that such background art is widely known or forms part of the common general knowledge in the field.

Given the ready availability of greenhouse gases such as carbon dioxide, especially sequestered carbon dioxide (CO ₂ ), it would be desirable to provide a method of producing energy and a system for producing energy which utilises carbon dioxide. The advantages of using greenhouse gases such as carbon dioxide (CO ₂ ) _, include low costs and also utilising a greenhouse gas which has deleterious effects on the atmosphere and the environment.

Governments across the world are becoming increasingly concerned to meet international obligations on minimising carbon in the atmosphere so as to meet the requirements of international treaties such as the Rio Declaration (1992) and the Kyoto Protocol.

Thus, an object of the method and system of this invention may include production of energy using greenhouse gases such as CO ₂ or to provide an alternative method of production of energy and associated system when compared to the prior art. Thus, an object of the method and system of this invention may include production of energy using greenhouse gases such as CO ₂ or to provide an alternative method of production of energy and associated system when compared to the prior art.

SUMMARY OF THIS INVENTION

In accordance with an embodiment of this invention, there is provided a process for producing energy from a greenhouse gas comprising carbon dioxide comprising the steps of: a) providing a compressed greenhouse gas comprising carbon dioxide in at least one underground storage cavern;

b) feeding the compressed greenhouse gas comprising carbon dioxide to at least one power generating element to generate power and decompressed greenhouse gas comprising carbon dioxide;

c) compressing the decompressed greenhouse gas comprising carbon dioxide in at least one multistage compressor to form compressed greenhouse gas comprising carbon dioxide; and

d) transferring the compressed greenhouse gas comprising carbon dioxide to the underground storage cavern for storage of compressed greenhouse gas comprising carbon dioxide.

The process may further comprise storing excess decompressed carbon dioxide in a second underground storage cavern. The power generating element may also be a turbine. The power generated from the power generating element may also be fed into an existing power generating system. The process may also be a continuous process wherein no fossil fuels may be used to provide energy or heat in the process of this invention.

In another embodiment of this invention, there is a system for producing energy from a greenhouse gas comprising carbon dioxide comprising: a) a first underground cavern for storage of a compressed greenhouse gas comprising carbon dioxide;

b) a power generating element to generate power and decompressed greenhouse gas comprising carbon dioxide; and

c) a multistage compressor to form compressed greenhouse gas comprising carbon dioxide from decompressed greenhouse gas.

In one aspect of this invention, the greenhouse gas is carbon dioxide or carbon dioxide with a mixture of other gases including but not limited to nitrous oxide, propane and water vapour. In another aspect, the greenhouse gas is predominantly carbon dioxide.

The system for producing energy from a greenhouse gas comprising carbon dioxide may further comprise a second underground storage cavern for storing excess decompressed carbon dioxide. The power generating element in the system may also be a turbine. The system for producing energy from a greenhouse gas may also feed power into an existing power generation system. The system for producing energy preferably uses no fossil fuels to provide energy or heat in the process.

BMEF DESCRIPTION OF THE DRAWINGS

This invention will now be described, by way of example only, with reference to the accompanying drawings; in which:

Figure 1 depicts a greenhouse gas emission energy production method and system (preferably carbon dioxide and mixtures thereof) in accordance with a first embodiment of this invention.

In Figure 1, there is shown a system and method (10) for producing energy from a greenhouse gas which in this example is carbon dioxide and mixtures thereof. An underground storage cavern (12) stores compressed carbon dioxide (CO ₂ ) which is fed through a valve (14) to a turbine (16) where the compressed CO ₂ drives the turbine (16) so as to generate electricity to an electricity grid (17). The compressed CO ₂ is decompressed by the turbine (16) and is fed through valve (18) to a multi-stage compressor (22) where the carbon dioxide is compressed again before being pumped to the underground storage cavern (12). Excess decompressed CO ₂ is stored in another underground storage cavern (26) with an excess cavern (28) also being in communication with the underground storage cavern (26).

In use, the compressed CO ₂ is fed from the underground storage cavern (12) through valve (14) to the turbine (16) where electricity is generated. The source of CO ₂ for the underground storage cavern may be sequestered CO ₂ . The compressed CO ₂ is decompressed by the turbine (16) and fed through valve (22) to either the underground storage cavern (26) where there is excess decompressed CO ₂ or fed into the multistage compressor (22) through valve (20) to compress the CO ₂ . The compressed CO ₂ is then fed back into the cavern (12) to complete the circuit.

The compressed CO ₂ is in the form of a liquid which enables ease of storage of the fluid for the method and systems of this invention.

The advantages of this invention include the use of sequestered carbon dioxide to produce energy as well as serving to dispose of carbon dioxide from the atmosphere as mandated by international treaties and protocols.

Modifications and variations such as would be apparent to those skilled in the art are understood to be well within the scope of this invention. It will be understood that this invention should not be restricted to the particular embodiments described in the preferred embodiment.