the nature of the present invention may be more clearly understood from the following preferred but non - limiting examples . two samples of flue gas were obtained from a queensland black coal fired power station . the samples of flue gas were then analysed to determine their composition . the composition of the flue gas samples is set out in table 1 below . an average of sample 1 and sample 2 was calculated so as to produce an average flue gas composition . calculations were then performed to determine the quantity of oxygen required for the complete combustion of all flammable gases in the average flue gas composition . ratios of the total oxygen required ( comprising the sum of added oxygen and oxygen present in the average flue gas composition ) to fuel addition ( in the form of methane ) under various conditions of combustion is set out in table 2 below . it should be noted that for complete combustion of all flammable gases , some excess oxygen is required . therefore , the calculations used to produce the data in table 2 were based on maintaining a minimum oxygen concentration of 2 % ( dry v / v ) in the waste gas . the same combustion conditions as listed in table 2 were then used to calculate the useable thermal energy and thermal efficiencies of the secondary combustion of the average flue gas composition . these results are set out in table 3 below : also calculated were the chemical compositions of the waste gases following secondary combustion under the various combustion conditions set out in tables 2 and 3 . the results of these calculations are provided below in table 4 . finally , the specific carbon dioxide produced per unit of useable thermal energy produced , as well as the pure oxygen required per unit of useable thermal energy produced were calculated . these results are set out in table 5 below . the results presented in table 4 illustrate that at all combustion conditions , the method of the present invention yields a waste gas stream having significantly higher concentrations of carbon dioxide than the flue gas . furthermore , the method displays an increase in carbon dioxide concentrations in the waste gas with increasing temperature . it may also be seen in table 5 that the carbon dioxide produced per unit of useable thermal energy in the secondary combustion ( when using methane as a fuel ) is about half of that for the burning of coal in a power station . in addition , the combined carbon dioxide produced per unit of useable thermal energy for the primary and secondary combustion is less than that for the burning of coal in a power station . this clearly demonstrates that the method of the present invention results in a reduction of carbon dioxide per unit of useable thermal energy than a single combustion stage coal fired power station . preferred features , embodiments and variations of the invention may be discerned from the following detailed description which provides sufficient information for those skilled in the art to perform the invention . the detailed description is not to be regarded as limiting the scope of the preceding summary of the invention in any way . the detailed description will make reference to a number of drawings as follows : fig1 illustrates a schematic diagram of a method for the treatment of gas according to an embodiment of the present invention . in fig1 there is illustrated a schematic diagram of a method for the treatment of gas according to an embodiment of the present invention . the method includes a coal - fired power station including a first combustion vessel 10 in the form of a coal - burning furnace . flue gas leaving the furnace 10 is directed to one or more sensors 11 for sensing the type and quantity of constituent gases in the flue gas . information gathered by the one or more sensors 11 is fed to an information collection system ( not shown ), such as a computer , dcs . scada or the like . information collection is carried out in real time as the flue gas leaves the furnace 10 . after this , the flue gases are directed to a filtration system 12 in order to remove substantially all of the particulate matter from the gas . the particulate matter is collected and disposed of , although the method of disposal is dependent on the composition of the particulate matter . once the particulate matter has been removed from the gas , the flue gas is compressed in a compressor 13 , before being directed to a storage tank 14 . when required , the compressed flue gas is transferred from the storage tank 14 to a second combustion chamber 15 in the form of a second furnace . the flue gas , and in particular the hydrocarbon content of the compressed flue gas , is combusted in the second combustion chamber 15 in the presence of oxygen supplied from an oxygen tank 16 and a hydrocarbon fuel supplied from a fuel tank 17 . the second combustion chamber 15 is also provided with an electrical ignition system 18 to assist in the ignition of the mixture in the chamber 15 . the electrical ignition system 18 may be operated continuously , or may be operated only when required ( such as when restarting the furnace 15 after a shutdown ). in embodiments of the invention in which the electrical ignition system 18 is operated continuously , the electrical ignition system 18 may be operated with or without a pulsing function . the information collection system ( not shown ) analyses the information collected by the one or more sensors 11 and compares it to programmed information to produce analysed data . the analysed data is then relayed to the electrical ignition system 18 which in turn controls the relative quantities of hydrocarbon fuel and oxygen released from the fuel tank 17 and oxygen tank 16 , respectively , into the second combustion chamber 15 . thus , by controlling the quantities of hydrocarbon fuel and oxygen fed to the second combustion chamber 15 based on the composition of the flue gas , the information collection system ( not shown ) is able to generate a mixture within the second combustion chamber 15 that is not only efficient in terms of generating a large amount of heat from the secondary combustion chamber 15 , but will also minimise the generation of noxious or greenhouse gases . heat 19 generated by the combustion in the furnace 15 is used to create electricity in an electrical generator 20 ( which may comprise a turbine and generator , or any suitable alternative ), and the generated electricity is output to an electrical grid 21 . in the embodiment of the invention shown in fig1 , an efficiency control valve 22 directs a portion 23 of the heat generated in the second furnace 15 back to the first furnace 10 , where it is used to generate steam in a boiler ( not shown ), the steam being used to drive a turbine ( not shown ) and generate electricity . by directing a portion 23 of the heat generated in the second furnace 15 back to the first furnace 10 , the amount of coal required to be combusted in the first furnace 10 in order to achieve the necessary heat to operate the boiler ( not shown ) is reduced . waste gas 24 generated in the second combustion chamber 15 is directed to a scrubber ( particularly a wet scrubber ) or particle filter 25 to remove any residual particulate matter in the waste gas 24 . in addition , passing the waste gas 24 though the scrubber or particle filter 25 acts to reduce the temperature of the waste gas 24 . the waste gas 24 leaving the scrubber or particle filter 25 is brought into contact with a first gas separation membrane 26 . the membrane 26 is selectively gas permeable , meaning that certain gases ( in this case , carbon dioxide ) are able to penetrate the membrane 26 while other gases ( including nitrogen , oxygen and so on ) are unable to penetrate the membrane 26 . thus , the waste gas 24 is separated into a first concentrate stream 27 ( which is relatively high in carbon dioxide ) and a first reject stream 28 ( which is relatively low in carbon dioxide ). the first concentrate stream 27 is brought into contact with a second gas separation membrane 29 , and , once again , certain gases ( in this case , carbon dioxide ) are able to penetrate the membrane 29 while other gases ( including nitrogen , oxygen and so on ) are unable to penetrate the membrane 29 . thus , the first concentrate stream 27 is separated into a second concentrate stream 30 ( which has a higher carbon dioxide content than the first concentrate stream 27 ) and a second reject stream 31 ( which is relatively low in carbon dioxide ). in the embodiment illustrated in fig1 , the second concentrate stream 30 represents the final concentrate stream as the carbon dioxide content of the stream has reached the desired level . the second concentrate stream 30 may then be further processed . for instance , the second concentrate stream 30 may be collected as liquid or gaseous carbon dioxide and used in any suitable application . alternatively , the carbon dioxide may be sequestered in building products , synthetic rock or aggregate or the like in order to prevent the release of the carbon dioxide to the atmosphere . the first reject stream 28 and the second reject stream 31 ( both of which are low in carbon dioxide and high in gases such as nitrogen ) may be released to the atmosphere through a flue or stack 32 . if desired a portion 33 of the flue gas from the first combustion chamber 10 may also be released to the atmosphere . a significant advantage of the present invention is that the addition of a second combustion chamber 15 and associated membranes 26 , 29 does not require any redesign of an existing power station , and the additional equipment can be added to an existing flowsheet relatively easily . in the present specification and claims ( if any ), the word ‘ comprising ’ and its derivatives including ‘ comprises ’ and ‘ comprise ’ include each of the stated integers but does not exclude the inclusion of one or more further integers . reference throughout this specification to ‘ one embodiment ’ or ‘ an embodiment ’ means that a particular feature , structure , or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention . thus , the appearance of the phrases ‘ in one embodiment ’ or ‘ in an embodiment ’ in various places throughout this specification are not necessarily all referring to the same embodiment . furthermore , the particular features , structures , or characteristics may be combined in any suitable manner in one or more combinations . in compliance with the statute , the invention has been described in language more or less specific to structural or methodical features . it is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect . the invention is , therefore , claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art .