LHV vs HHV in Data Centers: The Point of View of Clarke Energy

With the data center boom, technology in this sector has had to face the choice between various power generation and delivery systems. This is without considering burning issues such as cooling. We have drawn on the insights of Alex Marshall on LinkedIn, on behalf of Clarke Energy, regarding  the difference between Lower Heating Value (LHV) and Higher Heating Value (HHV).

Clarke Energy explains the Practical Difference between HHV and LHV

• Higher Heating Value (HHV) represents the total energy content of the fuel, including the latent heat stored in water vapor.
• Lower Heating Value (LHV) excludes this latent heat and represents the energy actually available for conversion into mechanical and electrical power in an engine.

Because gas engines cannot recover the latent heat, engine efficiency is always stated on an LHV basis. This applies whether engines are used for prime power, grid-parallel operation, or standby within a microgrid architecture.

Regarding Data Center Projects

Data center operators increasingly compare onsite generation against grid power, utility tariffs, and alternative technologies. If one solution is evaluated using HHV and another using LHV—often unintentionally—the comparison becomes misleading.

Key implications include:

• Efficiency benchmarking: Gas engines may appear less efficient if compared against HHV-based figures from other technologies.
• Fuel cost modeling: Engines consume fuel based on LHV performance, while gas is billed using HHV.
• PUE and energy reporting: Misaligned assumptions can skew internal performance metrics and sustainability reporting.

For natural gas, the typical ratio is:

HHV ≈ 1.108 × LHV

While this difference may appear modest, across multi-megawatt facilities operating thousands of hours per year, the financial impact is significant.

Fuel Billing vs. Engine Performance

In the US, fuel suppliers bill natural gas using HHV, expressed in kWh or MMBtu. This is the value that appears in gas supply contracts, utility bills, and operating expense models.

However, engine fuel input, efficiency, and power output are governed by LHV.

For accurate data-center financial modeling:

• Use LHV for engine sizing, efficiency calculations, and performance guarantees
• Use HHV for fuel cost calculations and operating expense forecasts

Aligning these two perspectives is essential to producing reliable long-term cost projections—particularly for campuses deploying onsite generation at scale.

LHV and Gas Infrastructure Sizing

LHV also determines the volumetric gas flow rate required to support a given electrical load. The energy input required by the engine is fixed; if the LHV of the supplied gas changes, the gas flow rate must change accordingly.

This affects:

• Gas supply capacity and redundancy
• Pressure regulation and metering
• Contracted gas limits and future expansion headroom

For data centers planning phased expansion or modular deployment, this becomes a critical infrastructure consideration.