How to Select Generator Sets with Different Fuels: Economic Analysis and Decision Guide

1. Background and Analytical Framework

A user consulted on the fuel selection for a 20kW generator set, requiring an economic evaluation of gasoline, diesel, methanol, and liquefied petroleum gas (LPG) from the perspective of energy consumption. This analysis quantifies the "fuel consumption - unit price - cost" model under full-load operation, comparing usage costs in four regions: China (Asia), Mexico (North America), Spain (Europe), and South Africa (Africa), to provide a scientific decision-making basis.

2. Fuel Consumption Calculation (20kW Generator at Full Load for 1 Hour)

2.1 Gasoline Generator

Conventional power generation efficiency: 270g gasoline per kWh.

Total consumption for 20kWh:

20 kWh × 270 g/kWh = 5400 g

Volume conversion at gasoline density 0.722g/mL:

5400 g / 0.722 g/mL ≈ 7.48 L

2.2 Diesel Generator

Fuel consumption: 215g diesel per kWh.

Total consumption for 20kWh:

20 kWh × 215 g/kWh = 4300 g

Volume conversion at diesel density 0.86g/mL:

4300 g / 0.86 g/mL = 5.00 L

2.3 Methanol Generator

Fuel consumption: 445g methanol per kWh.

Total consumption for 20kWh:

20 kWh × 445 g/kWh = 8900 g

Volume conversion at methanol density 0.79g/mL:

8900 g / 0.79 g/mL ≈ 11.26 L

2.4 LPG Generator

Industry data shows full-load consumption of ~5kg LPG per hour (calculated at the median density of 0.5-0.58kg/L).

3. Multi-Regional Fuel Cost Comparison (USD)

Region	Gasoline Cost	Diesel Cost	Methanol Cost	LPG Cost
China (Asia)	8	5	2.59	3.2
Mexico (NA)	9.33	6.33	2.93	6.85
Spain (EU)	12.34	6.8	2.93	10
South Africa (AF)	8.77	5.91	2.85	6.85

4. Decision Conclusions and Recommendations

4.1 Economic Ranking

Methanol (2.59-2.93 USD/h) < Diesel (5.00-6.80 USD/h) < LPG (3.20-10.00 USD/h) < Gasoline (8.00-12.34 USD/h). Methanol offers the lowest cost due to its low unit price (0.23-0.26 USD/L).

4.2 Application Suggestions

• Prioritize methanol generators where methanol is readily available (e.g., regions with industrial by-product methanol), reducing fuel costs by over 50%;
• Choose diesel generators if methanol is unavailable, as their energy efficiency (215g/kWh) outperforms gasoline generators (270g/kWh);
• LPG and gasoline generators are recommended only for special scenarios (e.g., remote areas without pipeline access), with caution advised in Spain due to high LPG costs (10 USD/h).

5. Extended Considerations