Sometimes it can. Often, though, the engines themselves are the limit, and the real choice is between converting part of the station and adding HFO-capable engines alongside it. This page explains how to tell which applies and what a conversion involves.
Step One: Can the Engines Burn HFO?
Most high-speed diesel gensets cannot burn heavy fuel oil. Their injection systems, combustion chambers and materials are designed for light distillate fuel, and HFO would quickly foul and damage them. For those engines, conversion is not realistic.
Some medium-speed engines, on the other hand, are designed to run on either fuel, or can be converted with new fuel injection equipment, heated fuel lines and changes to the engine settings. If the station already has medium-speed engines, the first step is to check with the engine specialist whether each model is HFO-capable and what conversion it needs.
What Has to Be Added Around the Engines
Even where the engines can burn HFO, the station needs systems a diesel plant does not have. These are the bulk of most conversion projects.
- Heated storage tanks, or heating coils added to existing tanks, to keep the fuel pumpable.
- A fuel treatment plant with separators to remove water and solids, and heaters to bring the fuel to injection viscosity.
- Heated and insulated fuel piping from treatment to each engine.
- Sludge handling for the residue the separators remove.
- A light fuel supply kept in place for starting, stopping and flushing the engines.
- Heat sources for all of this, often waste heat from the engines with a boiler as backup.
Convert, Add or Replace?
| Option | When it fits | Main drawback |
|---|---|---|
| Convert existing engines | Medium-speed engines that are HFO-capable and in good condition | Downtime during conversion; fuel systems still needed |
| Add HFO engines alongside | High-speed diesel fleet that must keep running | New engine hall and fuel plant |
| Replace the station | Old diesel fleet near the end of its life | Largest investment |
Our article on diesel station life extension versus replacement helps frame the long-term choice, and HFO versus diesel fuel strategy covers the fuel economics in general terms.
Fuel Quality and the Fuel Farm
HFO quality varies more than diesel. Density, viscosity, sulphur, water, ash and catalytic fines all affect how well the fuel treatment plant and engines cope. A conversion plan should include a fuel sampling programme, clear purchase specifications and a laboratory routine. USP&E’s notes on heavy fuel oil quality explain what to test for.
The fuel farm usually needs rework too: bunding, drainage, tank heating, unloading for viscous fuel and segregation between HFO and diesel. Our page on fuel farm design for diesel stations is a useful starting point.
Running and Maintaining the Converted Station
HFO operation is more demanding than diesel. Operators must manage fuel temperatures, separator performance and changeovers between fuels, and maintenance intervals for injectors, turbochargers and cylinder components usually shorten. Training and an updated maintenance plan are part of the conversion, not extras.
USP&E has converted, extended and replaced engine stations for mines and utilities, supplies Wartsila, Bergen and Caterpillar MaK engines as an independent supplier and service company, and provides O&M afterwards. The company is certified to ISO 9001 for quality and ISO 45001 for safety and has 150+ power projects in 45+ countries behind it.
Conversion questions
Can a containerised diesel genset run on HFO?
Generally not. High-speed diesel engines are not designed for heavy fuel oil, so adding HFO-capable engines is usually the better route.
Do converted engines still need diesel?
Yes. Light fuel is normally used for starting, stopping and flushing, so a diesel supply stays in place.
What is the biggest part of a conversion project?
Usually the fuel treatment plant, heated storage and fuel piping rather than the engine work itself.
Does HFO increase maintenance?
Typically yes. Injectors, turbochargers and cylinder components need more frequent attention, and the fuel treatment plant needs its own maintenance.
Review Your Station
Send USP&E your engine list and running data, and we will assess conversion, addition or replacement. Browse multi-megawatt engine generators in stock, or call +27 10 822 2324 or email info@uspeglobal.com.
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