While diesel has been the conventional fuel of choice for backup generator sets because of its initial capital cost advantages, things are changing as regulations, costs and technologies have evolved, and, because of that evolution, natural gas generators have gained in popularity.
“Over the past 15 years, there have been numerous performance developments in gas generator set technology to improve fuel efficiency, reduce exhaust NOx emissions and increase ratings,” according to Clay Hardenburger, senior staff applications engineer for Kohler Co. Hardenburger is the author of a new whitepaper, Gas Generator Set Performance Characteristics, that takes an in-depth look at characteristics of natural gas powered generators, the fuel used, their applications, and more. (To get a copy of the free whitepaper, click here.)
“These key development characteristics combined with incentives to develop renewable energy biogas fuel sources have moved the industry forward to consider gas generator sets as the preferred electrical power generation technology for continuous duty applications when paralleled with the utility,” writes Hardenburger. “In addition, recent expansion of natural gas fuel sources in the United States has resulted in low fuel prices, which is also driving the marketplace to utilize gas generator sets for standby and prime applications typically served by diesel generator sets.”
Kohler Co.’s Power Division offers a slew of EPA emissions-certified LP and natural gas generators in the up to 400 kW range, delivering an installation-ready product for residential power and light commercial applications. Kohler also developed a new line of large natural gas generators that are designed specifically for standby, prime or continuous power applications in the North American market. The large gas gen sets range from 425 kW to 1300 kW (and growing). For applications that require larger industrial generator sets, contact Steiner’s Power Systems division experts and they can help you choose the most appropriate generator.
These natural gas generators run on relatively clean burning fossil fuels such as propane. The lower emission gaseous gen sets significantly reduce carbon monoxide and particulate emissions.
Get your generator locally from Steiner
Steiner Electric, a local authorized distributor of Kohler products, offers an extensive inventory of residential and commercial generators that primarily operate in standby-rated mode utilizing LP or NG fuel.
Models rated for residential and light commercial applications include the 14/20kW RESA models that feature Kohler’s PowerBoost Technology for improved starting power. The generator can easily start and run a 5-ton air conditioner. The 38/48/60kW RCL model offers quiet operation and the Fast-Response II excitation system that delivers excellent voltage response and short-circuit capability using a permanent magnet alternator. The 60kW ERESB model for light commercial application, which utilizes NG and LPG gas, and depending on voltage achieves
a multitude of standby ratings for both gas types. The 80 to 150Kw ERESD models have numerous features including the Fast-Response X excitation system, and sophisticated control systems.
In addition to Steiner’s large inventory of generators, as a registered, certified distributor of Kohler generators, generator experts are available 24 hours a day, 7 days a week for emergency situations. In addition, all Steiner generator experts undergo rigorous training programs that must first be completed and are routinely updated.
Burn it Lean, Burn it Rich
These models operate differently depending on the fuel used, mixture of air and fuel, applications and other factors. Often, there are tradeoffs such as between power and efficiency.
To help straighten out the web of generator options, and best understand the unique factors of each, Hardenburger’s whitepaper addresses the
performance characteristics found in gas generator sets that utilize different fuels and engines, power factor, generator set rating, load requirements, and more parameters.
Fuel sources, for instance, typically come in two categories: methane-based fuels sources and hydrocarbon-based fuel sources. As Hardenburger explains, methane-based fuels such as pipeline natural gas are for use in high-compression ratio, lean-burn engines. Hydrocarbon-based fuel sources such as propane can be used in low-compression ratio, rich burn engines.
Hardenburger says that gas engines are classified as either lean-burn or rich-burn combustion types. Each type has its own advantages and disadvantages depending upon the application.
Lean-burn engines are associated with high-electrical efficiencies, and are typically used in continuous parallel with the utility applications as a primary power source because of limited transient response capabilities. Whereas rich-burn engines are usually associated with applications where transient load response is more critical than fuel efficiency. They are typically applied in emergency standby applications where the generator set system is the secondary power source when utility power is not available.
Rich-burn engines are a better choice in applications where large transient load changes above 30% are required. An LPG fuel source can be utilized in these applications without derate if low compression ratio engines are utilized.
Lean-burn engines are a better choice in applications where the utility is always present, and the required operational capacity exceeds 8,000 hours per year. Fuel efficiency is a key consideration in continuous applications, so engines with high compression ratios are typically utilized. Heavy hydrocarbon fuels such as LPG cannot be utilized in these applications without significant engine derate.
To help understand the basics of gas generator characteristics, their benefits and tradeoffs, download the Kohler whitepaper, Gas Generator Set Performance Characteristics, or reach out to your local Steiner Power Systems application engineer at 1-800-STEINER (783-4637).