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Compressor Fuel Gas Calculator

Engine & Turbine Fuel Consumption Estimation

Compressor Fuel Gas Calculator
Estimates fuel gas consumption for gas engine and gas turbine compressor drivers. Accounts for altitude derating, ambient temperature derating, fuel gas heating value, and load factor to determine daily/annual fuel use and cost.

Driver Type & Rating

Rich-burn/lean-burn natural gas engine (RICE)
BHP
Nameplate rated power at ISO conditions (sea level, 59°F)
%
Percent of rated BHP; typical 75–95% for pipeline service
Tip: Gas engines are typically used for <5,000 HP. Gas turbines dominate above 5,000 HP where power-to-weight ratio and lower emissions are critical.

Fuel Gas Properties

BTU/SCF
Pipeline quality: 950–1100 BTU/SCF; field gas varies widely
$/MMBTU
For annual cost estimation; enter 0 to skip
hrs/yr
Typical: 8,000–8,400 hrs/yr for pipeline; 95% availability = 8,322 hrs
Note: Use HHV (higher heating value) for all fuel gas calculations. LHV (lower heating value) is approximately 90% of HHV for natural gas. Manufacturer heat rates may be quoted on LHV basis.

Site Conditions & Heat Rate

ft
Elevation above sea level; derating starts above 1,000 ft
°F
ISO standard is 59°F (15°C); derating above 59°F
BTU/BHP-hr
Gas engine BSFC: 7,000–8,500 BTU/BHP-hr (HHV basis)
Uncheck to enter manufacturer-specific value
Altitude Derating: Approximately 3% per 1,000 ft above 1,000 ft elevation for naturally aspirated engines. Turbocharged engines derate less (1–2% per 1,000 ft above 3,500 ft).

Quick Reference: Typical Heat Rates & Fuel Consumption

Driver Type Heat Rate (HHV) Typical Size Fuel Use (MSCFD/1000 HP) Application
Gas Engine (Rich-burn) 7,500–8,500 BTU/BHP-hr 100–3,500 HP ~7.5 Field, gathering
Gas Engine (Lean-burn) 7,000–7,800 BTU/BHP-hr 500–5,000 HP ~7.0 Pipeline, process
Gas Turbine (Industrial) 9,500–11,000 BTU/BHP-hr 3,000–30,000 HP ~10.0 Pipeline mainline
Gas Turbine (Aero) 8,500–9,500 BTU/BHP-hr 5,000–50,000 HP ~9.0 LNG, offshore
Electric Motor N/A (use kWh) Any N/A All; zero on-site emissions

📚 Learn the Theory

Gas engine vs turbine selection, derating factors, fuel conditioning, and emissions regulations (RICE MACT, NSPS JJJJ).

Read Engineering Guide →

Formula

Fuel Gas Consumption:
Q = BHP × LF × BSFC / HHV

In MSCFD:
Q(MSCFD) = Q(SCF/hr) × 24 / 1000

Altitude Derating:
f_alt = 1 - 0.03 × (Alt - 1000) / 1000
(for Alt > 1,000 ft)

Temp Derating:
f_temp = 1 - 0.005 × (T_amb - 59)
(for T_amb > 59°F)
Q = Fuel gas flow (SCF/hr)
BHP = Rated brake horsepower
LF = Load factor (decimal)
BSFC = BTU/BHP-hr (heat rate)
HHV = BTU/SCF (fuel heating value)
f_alt = Altitude derating factor

Standards & References

  • GPSA
    13th/14th Edition, Section 13 & 15
  • 40 CFR 63 Subpart ZZZZ
    RICE MACT (Emissions)
  • 40 CFR 60 Subpart JJJJ
    NSPS for SI Engines
  • API 616
    Gas Turbines for Petroleum Industry
  • API 618
    Reciprocating Compressors

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