Heating Value

HHV vs LHV

When selecting Powermax Energy gas generator sets, two core heat value indicators – HHV and LHV – are key reference benchmarks. Our energy efficiency ratings for all gas-fired generator sets are calibrated based on the low heat generation (LHV) of the fuel.
When hydrocarbon fuels are completely burned, they will produce water vapor, whose vapor volume is proportional to the hydrogen content in the fuel. The combustion chamber operates at extremely high temperatures, allowing water to exist in the form of steam, thereby retaining the latent heat of evaporation contained within the steam. This latent heat energy is the key difference in distinguishing between high heat value (HHV) and low heat value (LHV) calculations.

HHV ( Heat generation) is used to measure the total heat released per unit of fuel, including the latent heat contained in the steam in the exhaust gas. In some thermal facilities, this steam can be condensed to recover additional heat. However, the exhaust temperature of gas engines is always higher than the condensation point of water; The steam carrying latent heat is discharged through smoke and is not utilized.
LHV (Net Heat Value) subtracts the unrecoverable latent heat vapor heat from HHV, representing the available thermal energy that can be converted into electrical energy for gas engines. All energy input designs for Powermax-Energy gas equipment must be based on LHV as the benchmark standard.

Typical Calorific Value Range of Gas Sources

Blast-Furnace Gas

3.6 – 4.3 MJ/Nm3
1.0 – 1.2 kWh/Nm3

Syngas

4.3 – 5.0 MJ/Nm3
1.2 – 1.4 kWh/Nm3

Biomass Gas

4.3 – 5.8 MJ/Nm3
1.2 – 1.6 kWh/Nm3

Producer Gas

5.4 – 6.1 MJ/Nm3
1.5 – 1.7 kWh/Nm3

Pyrolysis Gas

5.4 – 7.2 MJ/Nm3
1.5 – 2.0 kWh/Nm3

Semi-Coke Gas

6.1 – 7.2 MJ/Nm3
1.7 – 2.0 kWh/Nm3

Coal Gas

14.7 MJ/Nm3
4.1 kWh/Nm3

Coke Gas

17.3 – 18.7 MJ/Nm3
4.8 – 5.2 kWh/Nm3

Landfill Gas

18.0 – 20.9 MJ/Nm3
5.0 – 5.8 kWh/Nm3

Biogas

20.5 – 23.4 MJ/Nm3
5.7 – 6.5 kWh/Nm3

Sewage Gas

24.5 MJ/Nm3
6.8 kWh/Nm3

Coal Bed Methane

34.5 MJ/Nm3
9.6 kWh/Nm3

Natural Gas

33.5 – 35.6 MJ/Nm3
9.3 – 9.9 kWh/Nm3

CNG

33.5 – 35.6 MJ/Nm3
9.3 – 9.9 kWh/Nm3

Coal Mine Methane

36.0 – 39.6 MJ/Nm3
10.0 – 11.0 kWh/Nm3

LPG

46.1 – 50.4 MJ/kg
12.8 – 14.0 kWh/kg

LNG

46.1 – 54.4 MJ/kg
12.8 – 15.1 kWh/kg

Propane

96.5 – 100.4 MJ/Nm3
26.8 – 27.9 kWh/Nm3

Powermax Energy Solutions

Fuel suppliers typically report prices and volume costs based on HHV indicators. For natural gas, the ratio of HHV to LHV is approximately 1.108:1. When conducting an economic return analysis of our combined heat and power (CHP) solution, HHV data should be used to accurately calculate operating fuel costs.
The lower heating value (LHV) of the fuel directly determines the gas supply flow required to enter the Powermax Energy gas engine. Each unit has a fixed total energy demand to achieve the target power output, so the gas supply must match the heat input defined by the LHV level.
LHV is usually expressed in MJ/Nm ³. Based on the known power input requirements of the equipment, operators can immediately use this standard unit to calculate the hourly gas consumption, which facilitates system planning and operation monitoring.