attractive numbers than are used in conventional power plant terms. The conventional power industry had used HHV (high heat value) exclusively for decades, even though virtually all of these plants did not condense exhaust either. American consumers should be aware that the corresponding fuel-consumption figure based on the higher heating value will be somewhat higher. The difference between HHV and LHV definitions causes endless confusion when quoters do not bother to state the convention being used. since there is typically a 10% difference between the two methods for a power plant burning natural gas. For simply benchmarking part of a reaction the LHV may be appropriate, but HHV should be used for overall energy efficiency calculations if only to avoid confusion, and in any case, the value or convention should be clearly stated. Accounting for moisture Both HHV and LHV can be expressed in terms of AR (all moisture counted), MF and MAF (only water from combustion of hydrogen). AR, MF, and MAF are commonly used for indicating the heating values of coal: AR (as received) indicates that the fuel heating value has been measured with all moisture- and ash-forming minerals present. MF (moisture-free) or dry indicates that the fuel heating value has been measured after the fuel has been dried of all inherent moisture but still retaining its ash-forming minerals. MAF (moisture- and ash-free) or DAF (dry and ash-free) indicates that the fuel heating value has been measured in the absence of inherent moisture- and ash-forming minerals. Heat of combustion tables Note There is no difference between the lower and higher heating values for the combustion of carbon, carbon monoxide and sulfur since no water is formed during the combustion of those substances. BTU/lb values are calculated from MJ/kg (1 MJ/kg = 430 BTU/lb). Higher heating values of natural gases from various sources The International Energy Agency reports the following typical higher heating values per Standard cubic metre of gas: Algeria: 39.57MJ/Sm3 Bangladesh: 36.00MJ/Sm3 Canada: 39.00MJ/Sm3 China: 38.93MJ/Sm3 Indonesia: 40.60MJ/Sm3 Iran: 39.36MJ/Sm3 Netherlands: 33.32MJ/Sm3 Norway: 39.24MJ/Sm3 Pakistan: 34.90MJ/Sm3 Qatar: 41.40MJ/Sm3 Russia: 38.23MJ/Sm3 Saudi Arabia: 38.00MJ/Sm3 Turkmenistan: 37.89MJ/Sm3 United Kingdom: 39.71MJ/Sm3 United States: 38.42MJ/Sm3 Uzbekistan: 37.89MJ/Sm3 The lower heating value of natural gas is normally about 90% of its higher heating value. This table is in Standard cubic metres (1atm, 15°C), to convert to values per Normal cubic metre (1atm, 0°C), multiply above table by 1.0549. See also Adiabatic flame