Continuous Power Generator Buying Guide

Continuous Power Generator Buying Guide

How to Choose a Prime Power Generator

Heavy-duty applications require heavy-duty power. And, unfortunately, some of the most demanding industrial jobs are isolated from a central electrical grid.

Gillette Prime Power Generator

In other instances, the task at hand is so critical that there isn't room for any utility power outages, like a hospital or cold-storage facility.

If you manage such an industrial or critical facility, then you need a constant source of electrical power that only a continous power generator can provide.

What are Contiuous Power Generators?

Continuous power generators, also known as prime power generators, serve as the primary source of electrical power for a given application and typically have an output ranging between 25 kilowatts and 1 Megawatt. They can run continuously (24/7) at variable and maximum loads to completely replace the utility provider, if necessary.

Prime-rated generators are not to be confused with emergency standby generators, which are meant for emergency power only. Typically, standby generators shouldn't be run for more than 200 hours per year and cannot permanently replace the utility provider. Continuous power generators, on the other hand, can run for an unlimited number of hours when properly maintained.

Prime power diesel and natural gas generators are available. We will discuss the pros and cons of each fuel type in more detail below.

Who Uses Prime Power Generators?

Prime power generators are used as the main power source in a variety of industrial, medical, and heavy commercial applications.

  • Gas IndustryMicrogrids around the country must, by definition, operate independently of electric utilities and require prime power.

  • Fracking and mining applications are often in remote areas of the country and need prime power to stay in operation.

  • Off-grid military bases need their own source of power to operate anywhere in the world, from the front lines to the home front.

  • Hospitals and critical medical facilities use prime-rated generators to guarantee that their life-giving equipment will stay powered no matter what.

  • The cannabis cultivation industry, among the fastest-growing in the country since legalization, needs prime power for its vast agricultural facilities.

Primary generator uses and applications go beyond the short list above. Any remote or off-grid need is a possibility.

EPA Tier 4 Regulations

Before making any continuous power generator purchase, you need to determine whether your application falls under the Environmental Protection Agency's (EPA's) Tier 4 regulations.

Tier 4 is designed to reduce emissions, such as nitrogen oxides and particulate matter, from diesel engines. If your application intends to use a diesel generator as its primary power source, then you need a unit that meets Tier 4 requirements.

However, using a natural gas prime power generator is environmentally cleaner and therefore does not fall under Tier 4. But, natural gas generators are
subject to their own special EPA compliance guidelines.

It's important to familiarize yourself with the full extent of Tier 4 regulations (diesel) and EPA guidelines (natural gas). Find more information in the EPA's Regulations for Emissions from Heavy Equipment with Diesel Engines.


Prime Power InstallationInstalling a prime power generator is an involved process that should be handled by a certified installer that specializes in prime power or industrial applications.

One of the most important aspects of the installation process is being aware of local codes and standards, especially air quality compliance boards. These typically supersede EPA requirements and can be more exacting.

South Coast Air Quality Management District
(SCAQMD) in southern California is a good example of a local/regional compliance board that has mandatory requirements governing engine emissions, such as those coming from prime power generators. Anyone installing prime power in that region, or regions with similar regulations, will need to familiarize themselves with those codes.

Because applications are so varied, in most cases your generator will need to be customized and built-to-order. Expect to undertake a thorough sizing and planning process with your manufacturer before anything gets installed.

Prime Power Load Management

In some instances, continuous power generators can be used alongside utility power to benefit everyone involved.

For example, the utility provider will supply a user with power up to a certain threshold. Once that threshold is reached (usually during peak usage), the user's generator will provide any supplemental power to make up the difference.

The utility will often pay the user for providing the additional power. It can also work in reverse with the generator running at a fixed output. If demand peaks, the utility provider makes up the power difference.

These load management deals allow the utility to more effectively predict and manage the amount of power supplied across the entire grid. They also minimize the electrical burden on both the utility and end-user while allowing both to meet their power goals.

Diesel vs Natural Gas

As mentioned above, there are pros and cons to both diesel and natural gas prime-rated generators. The table below compares the two types.

Diesel Prime Power
Gas Prime Power
Diesel Prime Power natural Gas Prime Power
Less maintenance/downtime More maintenance/downtime
Smaller in size Larger in size
Louder Quieter
Can be more expensive due to Tier 4 requirements Less expensive; no Tier 4 requirements
Diesel must be acquired and stored; not as readily available A gas line provides consistent fuel; can be interrupted in disasters

Ultimately, your continuous power generator fuel choice should reflect the needs of your application. For example, someone in the fracking business will have access to cheap natural gas. On the other hand, a military base far away from a gas line will obviously need to choose diesel.

Considering the application, along with the equipment/maintenance costs and current fuel prices, will help you make the right choice.


Gillette SPJD-1000In order to operate continuously at peak performance, prime-rated generators should be on a regular maintenance schedule. You should base this schedule on NFPA 110 standards, manufacturer recommendations, and environmental conditions such as altitude and humidity.

Large companies might have an in-house engineer who can handle maintenance, while smaller ones can hire a local generator contractor. Some manufacturers also offer maintenance services themselves.

Typical maintenance includes:

  • Inspecting the system (engine, battery, fluid levels, air flow, etc.)
  • Replacing or upgrading worn parts
  • Changing the fuel and air filter

The most important aspect of maintenance is to have a trained and certified professional doing it consistently. Never skimp on maintenance; otherwise, problems may creep up when you can least afford them.

Picking Prime

Ultimately, installing a prime power generator isn't about choice; it's about necessity. If you need continuous, reliable power and don't plan on using the utility, then you need prime power.

Once you recognize this need, you should familiarize yourself with EPA regulations depending on which fuel choice is best for your particular application. Finally, ensure that a licensed professional installs and maintains the generator throughout its life.

If you're understandably hazy about this whole process, our in-house, factory-trained product experts are here to answer questions and make recommendations.

You can even discuss sizing, pricing, and financing by calling:
1 (800) 800-3317.

NEXT: Shop Prime Power Generators

Jared, the Generator Expert
Generator Expert
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