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Power Generation

During power outages, emergency backup electrical generators powered by diesel engines provide reliable, immediate, electric power to protect public health and safety and minimize economic losses.

Emergency backup electrical generators help save lives. That’s because losing power, even for a little while, can create situations threaten public health and safety. Blackouts also wreak economic havoc on businesses. Consider our dependence on technology and interconnected systems that rely on electricity, and you’ll see that power reliability is critical. Hospitals, data centers, water supplies, sewage treatment systems, fueling stations, communication outlets, and transportation systems require non-stop power.

Diesel generators are a technology of choice for emergency and backup power systems because they can best provide immediate, full-strength, electric power when the primary power supply system fails.

The nation’s electrical grid is increasingly vulnerable to severe weather events and cybersecurity threats. Emergency preparedness and climate resilience plans are developed to ensure alternatives to ensure continuous electrical grid power. Technologies designed to restore power to full operation must be reliable and proven, which is why most all utility system operators rely on diesel emergency generators as part of their so called “black start” systems.

In 2020, extreme weather events accounted for 1.33 billion outage hours in 2020, up 70% since 2019. According to the U.S. Department of Energy, the cost of outages to the US economy is $150 billion annually. Market surveys of eight economic sectors including batch manufacturing, healthcare/hospitals, continuous manufacturing, digital economy, government/education, grocery/food stores, and retail found that a four hour power disruption costs individual businesses an average of $10,000 to $20,000.

Features of Diesel Powered Electrical Generators

  • Quick start-up time: 10 seconds or less. Other fuel sources may take up to two minutes, which may be too long in many emergency situations and out of compliance with health and safety codes and state and federal laws.
  • Power density/fuel efficiency: Due to the chemical structure of diesel fuel, more energy is released per unit than any other source of commonly used power. For the same size engine, a diesel can produce twice the kilowatts of a gas engine generator. Greater power density means less fuel consumption than other sources of fuel.
  • Continuous strength: Diesels provide a steady supply of power and can handle wide swings in power use. A diesel generator does not "flicker" or dip in power output when appliances such as a large air conditioner turn on, surge, and drain power. Gas and turbine engines can slow down when strained, causing failure of the electrical equipment.
  • Disaster utility: Diesel generators have their own self-contained fuel, which is readily available and replenishable.
  • Reliability: Diesel generators provide power quickly and continuously during power blackouts.
  • Availability: It is easy for any person, business, or facility to select, finance, install and service a generator in the United States. That’s because of a comprehensive system of local dealers, and readily available supplies of diesel fuel.
  • High quality power: Diesel units deliver a steady supply of high-quality power and superior performance for transient, or fluctuating, power demands. High-torque characteristics of diesel engines ensure high quality power is particularly essential for supporting sensitive electronics, telecommunications, and digital networks
  • Portability: In addition to stationary units, diesel generators of various sizes and capabilities are highly mobile and available to be transported and positioned in virtually any setting to meet emergency power needs. Clean diesel fuel supplies are readily available in most locations and portable tankage accompanies the mobile units.
  • Durability: High-quality generators and engines last 20,000 - 30,000 hours before their first overhaul. That's equivalent to one and one-half million miles in an automobile.

Many international building codes and standards effectively require diesel generators for code compliance because of the need for rapid response time, load carrying capacity, fuel supply and availability, and reliability.

For example, the National Electrical Code 517-13, as well as the California Electrical Code, requires all hospitals and critical care facilities to have backup power systems that start automatically and run at full capacity within 10 seconds after power failure. The California Building Code requires emergency facilities to operate during disasters. This effectively limits the use of natural gas as a source of power for generators in these settings because during a disaster, like an earthquake, gas lines are immediately turned off to avoid the risk of fire and explosion during a rupture.

Diesel generators for emergency use are available in a range of sizes all based on electricity demands. Units can be permanently installed at fixed locations such as hospitals. They can also be transported on a mobile trailer to disaster sites or other outage areas. The actual system consists of the diesel engine unit and generating system, fuel storage/supply, and electrical switchgear.

Emissions Performance, Regulations, and Standards

Since 2015, advanced technology diesel generators are manufactured to achieve near zero emissions for particulate matter and nitrogen oxide emissions. Modern prime power diesel generators emit 26 times less particulate matter than those manufactured a decade Ultimately product use and permitting requirements determines emissions performance of each diesel-powered generating unit.

Diesel generators are covered by a wide range of federal, state, and local requirements regarding emissions performance and operating conditions. Facility owners must determine the type of use and application for the generator — emergency, non-emergency standby or prime power. Federal regulations governing the hours of operation are different for emergency and non-emergency uses. Regulations do not limit the use of backup generators during emergency situations. However, federal regulations in place since 2006 limit the number of hours generators may be used for non-emergency purposes. State and local regulations may also stipulate the size, location, and use of generators. Additionally, federal regulations require the use of emission control devices to improve emissions for older, non-emergency, backup generators.

In 2006, the U.S Environmental Protection Agency (EPA) finalized the first national emission standards for new stationary diesel engines under the New Source Performance Standards (NSPS). The NSPS requires all new diesel engines to be certified to emission standards that generally follow EPA's non-road or marine mobile emissions standards which generally require over 90% reduction in emissions of particulate matter and nitrogen oxide.

Generators run on the same ultra-low sulfur diesel fuel used in commercial trucks and off-road engines and equipment. Advanced technology diesel generators are able to run on high-quality renewable and biodiesel fuel blends in prime power applications, not just diesel. Doing so helps reduce emissions.

Older, existing non-emergency diesel-powered generators are also subject to regulations under EPA's National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Reciprocating Internal Combustion Engines (RICE). In many cases, these regulations require retrofitting with emissions control technology such as a diesel oxidation catalyst in order to meet the requirements.

For more information, view Power Solutions for Ensuring Electric Grid Reliability and Resilience- Webinar.

Grid Reliability and Microgrids

While used most frequently as a source of emergency backup power, some diesel generators with specific emissions performance located at various businesses, industrial parts or college campuses are now part of the response options to shore up the electrical grid during times of peak electrical demand and risk of brownouts or blackouts.

One option for responding to high electricity demand days and preventing grid failures is to bring on supplemental electrical supply through the strategic use of existing standby diesel generators in a “demand response” mode. In this instance, during periods of peak electrical demand, the generator owner activates the building generator to take the electrical demand off of the grid. Or, in some instances, operates the generator to put power back into the grid. Through the use of diesel generators in this way, load on the grid is reduced during periods of high demand, thereby avoiding more prolonged use of emergency generators in the case of a power outage. While wind and solar energy, is clean, it is also intermittent. So stationary generators are needed as well to provide ongoing power reliability.

Diesel generators are also incorporated into new Microgrids; self-sustaining networks providing and distributing electrical power outside the conventional utility service. Microgrids integrate the use of solar and wind for generating prime power, batteries for storage, and backup diesel generators to backstop any shortages of prime or stored power for example during extended periods of cloudy weather or calm winds when prime power generation is greatly diminished. Rural or remote locations where grid power and other fuel sources are unavailable are common applications. The portability of diesel-powered generators, and their fuel storage also make them a great choice for temporary power needs like those used on construction sites.

Evaluating power needs to help businesses and cities protect critical facilities during a power outage, consider:

  • Assess the risk: Identifying your facility's critical loads is an important first step. Assign a cost to the risks associated with utility power interruptions, production losses, and downtime.
  • Install a standby generator: Frequent outages can disrupt production lines and have significant cost implications to businesses. While other generator drivers take up to two minutes to engage, diesel-powered generators are uniquely qualified to provide power quickly during a power outage and offer the most cost-effective source of reliable backup power available.
  • Have sufficient fuel storage: Diesel fuel's energy density, and the engine's high efficiency, allow for smaller fuel storage facilities compared to other fuels. That saves money. Still, it is important to make sure that you have sufficient fuel storage capacity on-site for an extended outage of several days.
  • Maintain your equipment: As required by electrical and safety codes, standby generators should be "exercised" periodically to ensure they will operate as designed in the event of an emergency.
  • Contract rental power: If installing your own standby generation is not feasible for your business, you might consider contracting with a firm to reserve rental generator power for use in the event of an extended outage.

Resources to Learn More About Diesel Technology in Power Generation and Providing Black Start Capabilities

DTF Webinar - Power Solutions for Ensuring Electric Grid Reliability and Resilience

DTF Webinar - Power Generation 101 – Technology Choice in Emergency Backup and Prime Power

DTF Webinar - Power Generation 201 – Industry Perspectives on Regulations and Requirements for Standby and Prime Power Generation

Caterpillar: Power Systems and “Black Start” Diesel Generator Provides Stand-Alone Capability

Cummins: Generators and Power Systems and Never in the Black - three Cummins diesel generator sets provide ‘black-start’ power for one of Australia’s largest gas-fired power stations, recently commissioned on the NSW central coast.

mtu: Power Generation Solutions

Deere: Generator Drive Standby/Stationary Power 

Volvo Penta: Industrial Power Generation Engines and Solutions

Isuzu: Power Generator Sets

Yanmar: Energy Systems 



Microgrids are a growing option for reliable off-the-grid electrical supply, integrating renewable sources like wind and solar with storage and back up from traditional fossil-fueled sources like diesel generators, which can also be fueled with renewable biofuels.


Ensuring continuous supplies of electricity are critical to daily living, but recent man-made and naturally occurring events have demonstrated the fragility of the nation’s electrical generating system and transmission grid. Grid power outages of several hours or several days result in severe economic disruptions. Weather-related events that knock out grid power are predicted to increase, and their economic costs are expected to rise. Recent notable weather events such as Hurricane Maria in Puerto Rico (2017), and Superstorm Sandy in the eastern US (2012) are prime examples of the severe consequences of extended electricity disruptions when the grid is substantially affected.

Reducing or eliminating reliance on the central electrical power utility and generating grid are the focus of microgrids. Microgrids are a system of decentralized electric power generation and distribution. Serving a smaller number of users in generally smaller area, these self-sustaining systems have been used successfully for decades by both the military as well as some isolated communities in Alaska and other areas around the world. 

Microgrids are typically a four-part integrated system: A prime power source- renewable electricity from solar or wind, storage capacity in the form of batteries or other technologies, fossil-fueled backup systems such as diesel generators, and advanced integrated control systems.

The back-up generators serve an important role when renewable prime power sources are intermittent, or not available due to weather, as well as when storage has been depleted. The integrated system enables the operator to minimize the use of more expensive fossil fuels as a prime power source but keeps them at the ready to ensure continuous electrical supply.


Whether decentralizing the generation of electrical power and its distribution to be less susceptible to grid outages or be more powered by renewables, microgrids are emerging as an important option in settings everywhere. That’s because microgrids include the renewables that you want with the reliability that you need.


Cities, colleges, industrial campuses seeking to reduce or eliminate reliance on the centralized electrical grid and/or establish new resiliency and climate change adaptation strategies are increasingly turning to microgrids.

While diesel engines have a long history of prime power source for generating electricity, the cost and access to continuous supplies of fuel can be an issue. Microgrids in Alaska have proven their value, as it is the state with the highest electricity costs and for many communities in remote locations, diesel generators have long served that role. To help lower costs and use the available, almost-free renewable sources of electricity, some communities in rural Alaska use windmills and solar panels for prime power while retaining diesel generators for most of their electricity needs. 

For other communities, needs are more focused on creating an alternative to central grid-generated power from fossil fuels to pursue more sustainable renewable sources of electricity such as wind and solar.

Microgrids: Sustainable Power for the Future