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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

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:

Resources to learn more about diesel technology in power generation and providing black start capabilities include:


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