The gas composition must be considered, because natural gas appliances are designed for gas with a heating value of about 1,000 BTU (British thermal units) per cubic foot, or nearly pure methane. If the gas contains more than a few percent non-flammable gases such as nitrogen or carbon dioxide, either these will have to be removed or it will have to be blended with higher-BTU gas to achieve "pipeline quality". If the methane composition of the coalbed gas is less than 92%, it may not be commercially marketable.