LNG liquefaction: electric-drive versus gas-turbine energy cost

AI-generated editorial illustration; it does not depict a verified project, actual prices or chart data.

1. Compare useful work, not fuel labels

Electric drives can reduce local combustion and separate compressor operation from turbine maintenance. They are not automatically cheaper. The economic comparison starts with identical refrigeration duty and compressor shaft work per tonne of saleable LNG. Feed composition, ambient temperature, cooling-water conditions, train loading and refrigerant arrangement affect this work. Substituting an electric motor for a gas turbine does not itself prove that the refrigeration cycle needs less shaft energy.

2. Market evidence through early October

The World Bank October 2 release puts Henry Hub at 2.77 USD/MMBtu in August and 2.95 in September, compared with TTF at 21.11 and 25.42. A liquefaction plant's fuel opportunity cost may be tied to feed-gas acquisition, alternative sales or a contract formula, not a distant hub. Gas consumed by the turbine cannot simultaneously be sold as LNG; however, valuing it at a delivered destination LNG price without subtracting transport and conversion costs overstates the local opportunity cost.

The October 6 EIA outlook, with October 1 cutoff, forecasts 2026 US wholesale electricity at 52 USD/MWh. A high-voltage plant's delivered bill also depends on network, demand and reliability arrangements. There is no observed full-October average or verified plant-specific August/September drive quotation in this comparison.

3. Physical boundary

EIA explains LNG as cooled natural gas enabling storage and transport. Here the modeled service is compressor shaft work only: 0.30 MWh per tonne LNG, deliberately hypothetical. Electric input is shaft work divided by motor-drive efficiency. Turbine fuel input is shaft work divided by thermal efficiency and converted with 3.412 MMBtu/MWh. Use one agreed HHV basis throughout. A fleet EIA heat rate is not a guarantee for a particular turbine at hot ambient conditions.

4. Worked energy-only comparison

Assume motor-drive efficiency 0.96, gas-turbine efficiency 0.30 on HHV, electricity 100 USD/MWh and fuel opportunity cost 8 USD/MMBtu. These are illustrative nominal USD inputs, tax excluded. Electric consumption is 0.30 / 0.96 = 0.3125 MWh/t. Turbine fuel is 0.30 / 0.30 × 3.412 = 3.412 MMBtu/t. The same LNG output denominator is used for both.

At 1000000 t/year, the modeled electric energy premium is 3954000 USD/year. That number excludes grid connection, transformer and drive losses outside the assumed efficiency, additional auxiliaries, capital, maintenance and outage production loss. If the agreed electrical meter includes such losses, do not add them again.

5. Price crossover and sensitivity

At the stated fuel price, equal energy-only cost occurs at 27.296 / 0.3125 = 87.3472 USD/MWh electricity. Electric prices of 60, 100 and 140 USD/MWh produce 18.75, 31.25 and 43.75 USD/t. Every 10 USD/MWh adds 3.125 USD/t; every 1 USD/MMBtu of gas adds 3.412 USD/t to the turbine case. These slopes help evaluate a power contract against a fuel-indexed alternative without predicting either price.

Illustrative electric-drive energy cost per tonne LNG at electricity 60, 100 and 140 USD/MWh; 0.30 MWh/t shaft work and 96% motor-drive efficiency are fixed. Gas-drive comparator is 27.296 USD/t, excluding capital and auxiliaries.

6. Contract and operating evidence

Require efficiency maps across load and ambient temperature, guaranteed output at the chosen inlet conditions, auxiliary consumption and the actual revenue-meter location. For the electrical option obtain connection capacity, protection coordination, harmonics, restart time and power interruption history. A low average tariff does not price lost LNG output during a grid disturbance. For the turbine option separate maintenance availability, fuel quality requirements and combustion emissions charges. If heat recovery has a genuine useful sink, quantify its avoided cost rather than assuming every thermal loss becomes a credit.

7. Questions and limitations

Does electric drive make LNG zero-emission? No. Electricity generation, feed treatment and upstream emissions remain; emissions accounting and local cash costs have different boundaries.

Can fuel gas be treated as free because the plant owns it? No. Use its feasible alternative value, constrained by the contract and physical outlet.

Is 87.3472 USD/MWh a procurement ceiling? Only for this energy-only model. Reliability, capital and maintenance can move the full-system crossover, while partial-load operation can change both efficiencies.

8. Sources and next decisions

Use World Bank gas benchmarks, EIA's dated forecast, LNG context and heat-rate scope with their stated boundaries. Continue to LNG voyage energy for transport and PPA profile risk for power procurement. The sizing tool supports the electrical equipment discussion, not a refrigeration performance guarantee.