A 200 MW natural gas Brayton cycle gas turbine power plant has a capacity factor of 90% and an overall efficiency of 42% based on lower heating value. Assume the natural gas is 90% methane (CH4), 8% ethane (C2H6), and 2% nitrogen by volume. The lower heating value of methane and ethane are 32.8 MJ/m3 and 58.4 MJ/m3, respectively. The density of natural gas at standard temperature and pressure (1 atm, 25°C) is 0.716 kg/m³. The mass fraction of carbon in the natural gas is 73.9%.

What is the lower heating value of the natural gas on a volumetric basis (MJ/m3)?