Use the diesel generator cost per kWh calculator below to quickly estimate the real-world operational expense of your diesel generator. Accounting for fuel consumption, fuel cost, and maintenance allows you to determine the true cost of power generation.
Diesel Generator Cost per kWh Calculator
Diesel Generator Cost per kWh Formula
The calculation is based on dividing the total hourly operating cost (fuel + maintenance) by the total power output (kW).
Cost/kWh = ( (C_fuel × R_consumption) + C_maintenance ) / P_output
Formula Source: EIA Power Generation Costs | EPA Generator Emissions Data
Variables
Understanding what each variable represents ensures an accurate cost estimate:
- Fuel Cost per Gallon (USD): The price you pay for diesel fuel, typically including taxes.
- Fuel Consumption (Gallons/Hour): How many gallons of fuel the generator consumes per hour at its current load. This is usually provided by the manufacturer.
- Generator Output (kW): The actual electrical load (in kilowatts) the generator is producing during the operating period.
- Hourly Maintenance Cost (USD/Hour): An estimated cost to cover scheduled maintenance (oil changes, filters, belts) and potential repairs, usually annualized and divided by operating hours.
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What is Diesel Generator Cost per kWh?
The Cost per Kilowatt-Hour (C/kWh) is the single most important metric for evaluating the operational efficiency and expense of any power generation source. For a diesel generator, this metric isolates the ongoing costs—primarily fuel and maintenance—and presents them as a direct cost for every unit of energy produced. This allows for direct comparison against utility grid prices or other generation methods like solar or natural gas.
A low C/kWh is crucial for businesses relying on generators for continuous or peak shaving power, as it directly impacts profitability. For backup power, knowing the C/kWh helps in accurately budgeting for potential outage scenarios. Since fuel accounts for the vast majority of operating cost (often 75-95%), optimizing consumption and purchasing fuel efficiently are key strategies to lower this figure.
How to Calculate Diesel Generator Cost per kWh (Example)
Follow these steps using the input fields provided for a real-world calculation:
- Determine Hourly Fuel Cost: Multiply the Fuel Cost per Gallon ($3.50) by the Consumption Rate (5.0 Gallons/Hour). Example: $3.50 * 5.0 = $17.50/Hour.
- Add Hourly Maintenance Cost: Add the estimated Hourly Maintenance Cost ($0.50) to the Hourly Fuel Cost. Example: $17.50 + $0.50 = $18.00 (Total Hourly Operating Cost).
- Input Generator Output: Specify the power output in kilowatts (kW). Example: 50.0 kW.
- Calculate C/kWh: Divide the Total Hourly Operating Cost ($18.00) by the Generator Output (50.0 kW). Example: $18.00 / 50.0 = $0.36/kWh.
Frequently Asked Questions (FAQ)
What is a typical C/kWh for a diesel generator?
It varies significantly, but typically falls between $0.20 and $0.50 per kWh, heavily dependent on the current diesel price and the generator’s load level (efficiency decreases at lower loads).
Does the size of the generator affect the cost per kWh?
Yes. Larger industrial generators are often more fuel-efficient per unit of energy produced than smaller, portable units. However, they also have higher capital and maintenance costs. The C/kWh is best when the generator is running at 70-80% of its rated capacity.
How can I reduce my generator’s C/kWh?
The most effective methods are: 1) Purchasing fuel in bulk when prices are low. 2) Ensuring the generator runs at its optimal load level. 3) Performing scheduled maintenance to keep the engine operating at peak efficiency.
Why is the cost per kWh higher than my utility bill?
Utility providers benefit from economies of scale, generating power at a massive scale and distributing it through an established network. Diesel generators have no such scale, making their operational C/kWh inherently higher than standard residential or commercial utility rates.