Temporary power is foundational to nearly every job site, event venue, and emergency operation. Whether you need a compact 20kW unit to keep a construction trailer running or a 500kW+ micro-grid powering an entire festival grounds, selecting the right generator determines whether your operation runs smoothly or grinds to a halt.

This guide walks through the key decisions involved in sizing, selecting, and deploying mobile generators for temporary applications.

Step 1: Calculate Your Load

Before selecting a generator, you need to know how much power your site actually requires. This starts with an inventory of every piece of equipment, tool, and system that will draw power simultaneously.

List each load by its wattage or amperage rating. For motor-driven equipment such as compressors, pumps, and HVAC units, account for startup surge, which can be 2 to 3 times the running wattage. Add all running loads together, then add the largest single startup surge on top of that total. This gives you your peak demand.

The 20% rule: Once you have your peak demand number, add 20 percent headroom. This buffer accounts for unexpected loads, future additions, and ensures the generator operates well within its optimal efficiency range (typically 50 to 80 percent of rated capacity). Running a generator at full capacity continuously accelerates wear, increases fuel consumption, and reduces the lifespan of the unit.

Common Load Examples

Equipment	Running Watts	Startup Surge
Construction trailer (HVAC + lights + outlets)	5,000 – 8,000 W	12,000 – 15,000 W
5-ton portable HVAC unit	6,000 W	18,000 W
Welding machine	7,000 – 10,000 W	12,000 – 15,000 W
Light tower (4-head LED)	1,200 – 2,000 W	Minimal
Security trailer	500 – 1,500 W	Minimal (solar primary)
Concrete pump	15,000 – 25,000 W	30,000 – 50,000 W

Step 2: Choose Your Fuel Type

The two primary fuel options for mobile generators are diesel and natural gas. Each has distinct advantages depending on your application, site conditions, and runtime requirements.

Diesel Generators

Diesel remains the workhorse of the temporary power industry for good reason. Diesel generators are more fuel-efficient than natural gas at equivalent output levels, typically consuming 15 to 20 percent less fuel per kilowatt-hour. They are also more durable under continuous heavy loads, making them the default choice for construction, oil and gas, and remote site applications.

Diesel fuel is energy-dense and widely available, and on-site fuel tanks can be refilled by tanker truck without interrupting operations. Most rental generators in the 100kW to 500kW range are diesel-powered. The primary downsides are higher exhaust emissions, louder operation (typically 75 to 85 dB at 7 meters), and stricter environmental regulations in some jurisdictions.

Natural Gas Generators

Natural gas generators are gaining ground in applications where noise, emissions, or fuel logistics are primary concerns. They run significantly quieter than diesel units (often 65 to 75 dB) and produce roughly 30 percent fewer NOx emissions. If your site has access to a natural gas line, fuel cost and logistics are simplified since there is no need for on-site tank storage or delivery scheduling.

Natural gas generators are increasingly common for events in urban areas, healthcare facilities, and commercial properties where noise ordinances or air quality regulations apply. They are generally less fuel-efficient than diesel under heavy loads but offer lower operating costs when connected to utility gas lines.

Step 3: Match the Configuration to Your Use Case

Generator needs vary dramatically by application. Here are common configurations for the industries Hoss serves most frequently.

Construction Sites

A typical mid-size construction site (5 to 15 acres) runs on a single 60kW to 150kW diesel generator powering construction trailers, tool charging stations, welders, and temporary lighting. Larger projects with tower cranes, concrete pumps, or on-site batch plants may require 250kW to 500kW units or multiple generators operating in parallel.

Events and Festivals

Large-scale outdoor events often require a micro-grid approach: multiple generators distributed across the venue to power stages, vendor areas, lighting, HVAC for VIP tents, and production equipment. A 50,000-person festival might use 6 to 10 generators ranging from 100kW to 400kW each, managed centrally with load balancing to optimize fuel consumption and provide redundancy.

Emergency and Backup Power

Facilities that lose grid power need generators with automatic transfer switches (ATS) that detect an outage and switch to generator power within seconds. Hospitals, data centers, and water treatment plants typically require N+1 redundancy, meaning one extra generator beyond what the load requires. For temporary backup applications, a towable generator with an ATS panel can be connected to a facility's main distribution in under an hour.

Fuel Management Considerations

Fuel is the largest ongoing operating cost for any generator. Effective fuel management can reduce costs by 10 to 25 percent and prevent the most common cause of generator failure: running out of fuel.

• On-site tank sizing: Size your fuel tank or belly tank for a minimum of 24 hours of runtime at 75 percent load. For remote sites, 48 to 72 hours of autonomy is recommended to account for delivery delays.
• Automated monitoring: Modern generators include telematics that report fuel level, consumption rate, and estimated time to empty. This data enables proactive refueling schedules rather than reactive emergency fills.
• Fuel delivery logistics: Establish a standing delivery contract with a local fuel supplier before the generator arrives on site. Emergency fuel delivery typically costs 30 to 50 percent more than scheduled deliveries.
• Spill prevention: All fuel storage and transfer must comply with EPA SPCC (Spill Prevention, Control, and Countermeasure) regulations. Use secondary containment around all tanks and follow proper transfer procedures.

Noise Considerations for Urban Sites

Noise is often the deciding factor in generator selection for urban construction, events, and commercial applications. Most municipalities enforce noise ordinances that limit construction equipment to 80 to 85 dB at the property line during daytime hours, with stricter limits (often 65 to 70 dB) during evenings and weekends.

To reduce generator noise impact, consider the following strategies:

• Select sound-attenuated enclosures: Factory-enclosed generators (often marketed as "super silent" or "quiet" models) typically operate at 65 to 72 dB at 7 meters, compared to 80 to 90 dB for open-frame units.
• Position generators strategically: Place the generator as far from property lines and occupied buildings as cable runs allow. Every doubling of distance reduces noise by approximately 6 dB.
• Use natural gas when possible: Natural gas engines are inherently quieter than diesel. For overnight or extended urban deployments, this difference is significant.
• Consider temporary sound barriers: Portable acoustic barriers or jersey barriers with absorptive panels can reduce noise by an additional 5 to 10 dB when positioned between the generator and sensitive receptors.

Getting the Right Generator for Your Project

Choosing the right generator involves more than matching a wattage number. The fuel type, enclosure rating, noise profile, fuel management plan, and site logistics all influence whether your temporary power solution performs reliably or becomes a liability.

Working with a full-service provider simplifies the process. A qualified partner will survey your site, calculate loads, recommend the right equipment, handle delivery and setup, and manage fuel and maintenance throughout the deployment. This end-to-end approach eliminates the coordination burden and ensures your power stays on.