When businesses evaluate diesel generator adoption, the most crucial operating cost—beyond equipment price—is fuel consumption.
So, how much diesel does a generator actually burn per hour?
How many liters does it take to produce one kWh of electricity?
And what factors affect fuel efficiency?
This article explains everything you need to know with simple formulas, reference charts, and real-world scenarios—to help you plan your TCO (Total Cost of Ownership) more accurately.
⛽How Much Fuel Does a Diesel Generator Use Per Hour?
Fuel consumption depends on key factors:
- Rated power (kW)
- Load factor (actual usage %)
- Engine efficiency (brand & design)
Rough formula:
Fuel per hour (L) ≈ Rated kW × Load % × 0.25~0.3
🔸 Example: A 100kW generator running at 70% load:
100 × 0.7 × 0.25 = approx. 17.5 liters/hour
⚠️ Actual results may vary depending on brand, model, and operating environment.
📊Fuel Consumption Reference Table (70% Load)
| Rated Power (kW)額定功率(kW) | Fuel/hr (L) | Fuel per kWh (L/kWh) |
| 30kW | ~5–6 | ~0.27 |
| 50kW | ~9–10 | ~0.26 |
| 100kW | ~17–18L | ~0.25 |
| 200kW | ~33–35 | ~0.24 |
| 500kW | ~80–85 | ~0.23 |
📌 Larger generators have lower fuel use per kWh, offering better economy of scale.
💡What Increases Your Fuel Usage?
- Running below 40% load for long periods （<40%）➜ poor efficiency, carbon buildup
- Poor maintenance ➜ clogged filters or fuel systems increase consumption
- Older/non-efficient models ➜ higher fuel use & emissions
- Harsh conditions (heat, humidity, altitude) ➜ lower engine performance
📦Real Case: 100kW Cummins Generator Annual Fuel Cost組一年油費試算
Scenario:
- Avg. use: 6 hrs/day × 300 days/year
- Diesel price: NT$30/L
- Consumption: 17.5L/hr
🔍 Total annual fuel use = 17.5 × 6 × 300 = 31,500L 🔍 Annual fuel cost = 31,500L × NT$30 = NT$945,000
✅ By switching to a high-efficiency model, you could save 1015%, or NT$100,000140,000 annually!
🔍 How to Lower Operating Costs
- ✅ Choose high fuel-efficiency models (e.g. Cummins series)
- ✅ Use smart load control to reduce low-load inefficiency
- ✅ Select Tier-certified eco-friendly engines
- ✅ Schedule maintenance and load testing regularly
📌Summary: The Right Generator Makes Fuel Costs Controllable
Fuel is unavoidable—but smart equipment selection, proper upkeep, and intelligent management can help your diesel generator operate with better efficiency and lower cost.
📞 Want to assess your current system’s fuel performance
or find the best-fit generator combo?
Contact KINGBEST powersystemtoday!
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