When the generator is the grid
Most generators exist to cover short outages. Some sites have no outage to cover because they never had a utility connection in the first place. Remote mines, construction camps, oil and gas field sites, island facilities and temporary events often rely on generators as their only electricity source for weeks, months or years. This is prime power duty, and it changes almost every selection decision.
A set rated for standby service is built on the assumption that it will run for limited hours. Run it continuously and it may wear far faster than expected. Prime-rated equipment is designed to run for long periods at a variable load, and some sites need continuous-rated units for a steady, near-constant load. The exact definitions vary by manufacturer and by the rating standard used, so read the rating’s fine print rather than assuming. The ideas below are general and do not replace professional engineering.
Step one: build a load profile
Because the generators must carry the whole site, you need to understand how demand changes over time. Start by listing every load: motors, lighting, heating and cooling, compressors, pumps, office and camp loads, and process equipment. For each, note its running power, how many hours it runs, and whether it starts under heavy load.
Then look at the shape of demand over a day and a season. Many sites have a high daytime peak and a low night base. A flat estimate of “average load” hides this, and matters because engines tend to run best within a middle band of their rating. Running at very low load for long periods can cause problems such as unburned fuel residue in some diesel engines, while running near maximum constantly shortens life.
A hypothetical illustration, not a recommendation: suppose a camp has a daytime peak of 400 kW and a night base of 120 kW. A single large unit would spend nights at a small fraction of its rating. Two or three smaller units that can be added or removed as demand changes would run closer to their best range. The right number depends on the real profile.
Step two: size and arrange the units
The usual approach is several generators operating in parallel, sometimes called a power plant arrangement. Parallel operation offers:
- Redundancy. If one unit fails or is serviced, others keep the site powered. A common principle is “N+1”, meaning enough units to meet the load with one spare, though how much spare capacity is reasonable depends on the site’s risk.
- Efficiency at part load. Units can be started or stopped to follow demand.
- Maintenance flexibility. A unit can come offline for service without a shutdown.
- Growth. Capacity can be added as the site expands.
The cost is complexity, including control systems for load sharing and synchronization, which should be designed and commissioned by qualified specialists. Sizing must also cover the largest motor starts, since a motor draws several times its running current as it starts, and electronic loads can distort the waveform. Altitude and ambient temperature reduce the output of many engines. Working out the numbers follows the same logic as generator sizing, with greater emphasis on continuous operation and redundancy.
Step three: choose the fuel
Fuel choice is mostly a logistics decision when the site is remote.
- Diesel is common because it is energy dense, easy to store in tanks and available in many places. Delivery by road, rail or ship may be the weak link.
- Natural gas suits sites close to a pipeline or a gas field. Where gas is a by-product of the site’s own operations, gas-fueled engines can be attractive, though gas quality must be checked against the engine’s requirements.
- Propane or other liquefied gas can be trucked but tank logistics and vaporization limits apply.
- Dual-fuel and hybrid systems mix fuels or add solar and batteries to cut run hours. Such hybrids draw on alternative power sources to reduce fuel burned.
For each choice, ask what happens if a delivery is late. Storage tanks sized to cover a defined period give a buffer, but they require containment, safe handling and rules compliance. The design of storage tanks, with spill containment and venting, is specialized work. Fuel quality also matters, since contaminated or aged fuel is a leading cause of engine trouble.
Step four: plan the logistics
Long runs require a plan for everything that gets consumed or worn:
- Fuel supply. Delivery schedule, storage volume, transfer pumps and filtration.
- Lubricating oil and coolant. Quantities for regular changes and top-ups.
- Maintenance windows. Service intervals are set by running hours, so a prime plant needs a schedule that rotates units without dropping the load.
- Spare parts. Filters, belts, hoses, sensors and critical items kept on site, especially in remote areas where shipping takes time. Deciding on critical spares is easier when you know which failures would stop the site.
- Skilled people. Operators and technicians able to run and troubleshoot the plant.
Step five: installation and protection
Engines need clean combustion air, adequate cooling, exhaust routing away from occupied spaces, and vibration isolation. Electrical distribution from the generators must include protective devices, a proper grounding system and arrangements for paralleling. Fire protection, fuel spill response and emergency shutdown are part of the design. All of this should follow local codes and be carried out by licensed professionals.
Weigh the alternatives honestly
Before committing, compare generator-only supply with a connection to the grid or with a hybrid approach. A line extension may cost a lot up front but reduce fuel and maintenance burdens. Adding solar or wind can cut fuel use, though results depend on local conditions. Cost estimates, emissions limits and permitting requirements vary widely, so treat any figure you read, including those from a supplier, as something to verify for your own site.
Summary checklist
- Know your load profile, not just a peak number.
- Choose a prime or continuous rating that matches how the set will really run.
- Use multiple units for redundancy and part-load efficiency.
- Treat fuel supply as seriously as the engine.
- Plan maintenance and spares before commissioning.
- Involve qualified engineers for design, installation and testing.