Start saving with bi-fuel diesel engines

Replace diesel fuel with natural gas


This Cummins engine has been retrofitted with a GTI-Altronic conversion system to allow simultaneous operation on diesel fuel and natural gas, thereby lowering the operating cost and reducing the on-site fuel storage requirement. Photo courtesy Altronic LTo avoid confusion, let’s define what we’re going to discuss: bi-fuel engines -- sometimes called dual-fuel engines -- use diesel fuel and natural gas simultaneously for stationary on-site electric generation.  The terms “bi-fuel” and “dual-fuel” can have various meanings. They are both used at times to describe engines that can burn multiple fuels, but individually, or engines that use combinations other than diesel fuel and natural gas. But this discussion focuses on diesel and natural gas as combination fuels for reciprocating engines.

Fuel Challenges

Owners of both standby and continuous-duty engine generators operating on diesel fuel alone face several challenges. It is expensive and space-consuming to have enough diesel fuel on site for continuous use or to supply standby generation that may need to operate for several days or longer. Diesel fuel is likely to continue to rise in price. Keeping liquid fuel in good condition also adds cost. Further, emissions from diesel engines operating long hours on diesel fuel only may exceed federal, state or local air quality standards.

A practical solution is to equip an existing engine or purchase a new engine to replace 70% to 80% of the diesel fuel with natural gas supplied via pipeline. Diesel fuel is still needed for pilot compression ignition but the necessary stored fuel quantities are much smaller. Natural gas on a $/MMBtu basis is far less costly in most markets, and bi-fuel operation dramatically reduces emissions of sulfur oxides, particulates and carbon dioxide.

Convert an Existing Engine

Several companies supply systems for conversion of recip engines to bi-fuel operation. These require no or minimal engine internal changes, and can be installed in a matter of hours. Because of lower fuel costs with natural gas, some owners of peaking generation systems may choose to operate these over longer hours or even continuously, thus reducing electric demand and energy charges. With longer operating hours comes the increased practicality of heat-recovery, making these installations true combined heat and power (CHP) systems.

Even pure standby diesel generation units can benefit from installation of bi-fuel capability, because the necessary onsite fuel storage and fuel holding costs are dramatically reduced, and system reliability improves with two potential fuel sources.

Package Conversion System

One system for converting existing diesel engines to bi-fuel operation is the GTI Bi-Fuel system from Altronic LLC. With this addition to the engine, natural gas is introduced downstream of the engine air cleaner and upstream of the turbocharger. The gas is supplied at approximately atmospheric pressure using a proprietary air-fuel mixer that provides a high level of gas mixing. The air-gas mixture is compressed in the turbocharger and distributed to each cylinder by the engine air-intake manifold.

The lean air-gas mixture is compressed during the compression stroke of the piston and ignited by the diesel injector. Flow of gas to the engine varies with the engine load. The system varies gas flow according to changes in engine vacuum level, thus allowing it to respond to engine fuel requirements while maintaining the integrity of the OEM governing system.

Short Paybacks for Prime Power

Multiple Caterpillar engines with bi-fuel conversions. Photo courtesy Altronic LLC.According to Steven Roix, Altronic GTI Sales Manager, the bi-fuel approach offers major savings to owners. “They are seeing rapid payback and huge savings on prime power and peak shaving applications. The lower fuel cost allows extending runtimes by 300% or more, depending on the type of installation.” For standby applications, the bi-fuel approach dramatically reduces the on-site fuel storage requirement.

Roix also points out that because of the cleaner burning characteristics of natural gas, typical installations reduce air emissions significantly. He notes that although the engine burns cleaner in the bi-fuel mode, the recommended service intervals do not change. “We always encourage customers to follow engine OEM maintenance instructions.”

The Altronic system monitors engine and fuel flow characteristics, and can quickly revert to all-diesel operation if there is an interruption or change in the flow of natural gas. Roix says, “It’s a simple add-on system that can be taken on and off easily.”

Bi-Fuel Capability from the Factory

Some generator package manufacturers offer bi-fuel capability with new generator sets. Generac offers bi-fuel as an option on its offering of standby diesel generation systems. Although these units are designed for standby service only, the bi-fuel capability still reduces fuel cost and makes a major reduction in the amount of standby fuel needed on site.

According to Michael Kirchner, Technical Support Manager for Generac, bi-fuel makes sense for many buyers of standby engines. “Because they run on both diesel and natural gas, they capitalize on both the availability of on-site diesel fuel (required by many authorities) and the long running times that come from utility-supplied natural gas. Because they typically run on a mix of about 75% natural gas, their running time is extended by a factor of four without a fuel delivery.”

Where Reliable Power is Essential

This Generac standby generator is factory-equipped for bi-fuel operation. For standby systems such as this, bi-fuelling reduces fuel cost, storage requirements and plant emissions. Photo courtesy GeneracAccording to Kirchner, Generac bi-fuel units are the only ones on the market that have this capability from the factory: Others need to be modified in the field. He notes that common applications for this product are health care facilities, data centers, and other facilities such as wastewater treatment plants and 911 call centers, where continuous access to electric power is essential.

Kirchner says that emission reduction by adoption of the bi-fuel option is variable, but the company has seen evidence of reduction of emissions of NOx and particulates in excess of 25%.

Might be an Opportunity

If your facility is currently using diesel fuel only for engine generation, it is worth considering the benefits of changing to a bi-fuel system. If you are looking at adding standby generation, it certainly is an important option. Ask your consulting engineer to look into potential savings and reduction in the need for on-site fuel storage. 

More Info:

Altronic LLC 

Cummins Dual Fuel Conversion

Caterpillar Dual Fuel Generator Conversion Information:


This story appeared in the Summer 2013 Gas & Technology supplement. See additional stories below.

The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
Doubling down on digital manufacturing; Data driving predictive maintenance; Electric motors and generators; Rewarding operational improvement
2017 Lubrication Guide; Software tools; Microgrids and energy strategies; Use robots effectively
Prescriptive maintenance; Hannover Messe 2017 recap; Reduce welding errors
The cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Mobility as the means to offshore innovation; Preventing another Deepwater Horizon; ROVs as subsea robots; SCADA and the radio spectrum
Research team developing Tesla coil designs; Implementing wireless process sensing
Commissioning electrical systems; Designing emergency and standby generator systems; Paralleling switchgear generator systems
Natural gas engines; New applications for fuel cells; Large engines become more efficient; Extending boiler life

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
Featured articles highlight technologies that enable the Industrial Internet of Things, IIoT-related products and strategies to get data more easily to the user.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Maintenance Manager; California Oils Corp.
Associate, Electrical Engineering; Wood Harbinger
Control Systems Engineer; Robert Bosch Corp.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me