Dual Fuel Technology

Test Aims To Combine Best Aspects Of Diesel And LNG The M/V Olympic project underway in Tacoma, Wash., will go into the record books as the "first" in many categories. Noteworthy among those is first marine mass transportation vessel fueled by both LNG and diesel utilizing the newest dual-fuel technology. Plus, first LNG training platform, first opportunity for U.S. Coast Guard (USCG) and ABS to set LNG standards, and first long-term economic and environmental impact study on LNG for the maritime industry. The Clean Air Act Amendments of 1990 and the Energy Policy Act of 1992 both paved the way for the coming growth of natural gas technology. Specifically mentioned in the legislation as an alternative energy source, natural gas' clean emission profile and domestic abundance make it of major interest.

Largely-overlooked bonuses are the good engine wear and maintenance characteristics achieved with natural gas fuel.

Compressed natural gas (CNG) has been a safe, reliable alternate fuel for transportation. Liquid natural gas (LNG) has seen some use in buses and as "boil-off" fuel from LNG cargo tankers.

LNG has two primary advantages over CNG: the ability to carry more fuel in the same space, and no need for large volumes of high-pressure gas. However, LNG presents its own tactical problems, cryogenic liquefaction being the most obvious.

Storage of the liquid in its - 260- degree "comfort zone" is another stumbling block.

For LNG to become universally available, liquefaction, or cryogenic, plants are needed relatively close to consumption sources. Specially-designed fittings and hoses used in the fueling process must be leakproof, and personnel must be trained in cryogenic handling techniques. Early problems with carbon steel holding tanks which failed at cryogenic temperatures have been rectified.

Today's tanks are constructed of eight percent nickel stainless steel, double-walled and vacuum-insulated.

High-horsepower commercial engines designed for use with LNG are nonexistent, but running a standard diesel engine on LNG reduces its power output by 25 - 40 percent. Until now, converting to gas meant investing in more power or reducing power production, two no-win scenarios.

Energy Conversions Inc. (ECI) of Fife, Wash, offers an alternative. A dual-fuel conversion kit developed by ECI Engineers allows largehorsepower, medium-speed diesel engines to run on 92 percent LNG and eight percent diesel, reportedly achieving the economic and environmental benefits of LNG while maintaining full diesel-rated power. The ECI conversion kit is designed for use on General Motors EMD model 645 two-cycle diesel engines.

Paul Jensen of ECI believes his company has proven the viability of the system on two locomotive engines currently in use by Burlington Northern Railroad.

The maritime connection for the MV Olympic project will include Marine Design Associates, Inc. (MDA) of Victoria, B.C. MDA developed the first approved CNG marine passenger vessel conversion for the British Columbia Ferry System.

MDA representative Bill Berlin states that natural gas vessels have shown "much less engine repair, multiple times over expected measures the same for lubricating oil and filters." Building on the experience gained on the two B.C. ferries, MDA will provide vessel engineering designs, as well as act as an interface between the consortium and the regulatory bodies.

Systems Management Sciences, Inc. (SMS) will provide contract and shipyard management services, and will work as primary interface between the project and the various governmental agencies. Prime operatives John Pounds and Wesley Moore will oversee both the conversion phase and the long-term testing procedures.

ECI and SMS have been working for nearly a year on the acquisition of the surplussed vessel, funding of the projected $5-million project, and coordinating the input from sources as varied as Russian cryogenic specialists in Moscow, Russia to the staff of the National Center for Advanced Transportation Technology (NCATT) in Moscow, Idaho. Integrated parties from the College of Engineering at Washington State University have also been involved.

Methane, the major component of natural gas, exhibits ideal knock characteristics for sparkignited engines, but not for compression-ignited engines like standard high-horsepower diesels. ECI's system injects a small amount of diesel oil near the top of the piston stroke. The diesel fuel with its lower ignition temperature acts as a pilot charge, igniting the gas mixture.

This approach requires a lower compression ratio than normal. To alleviate the lower efficiency generally associated with lower compression ratios, ECI's patented piston crowns and cylinder heads are specially designed to minimize loss and allow for full diesel-rated horsepower. The Gas Inlet Valve, an electricallyactivated pneumatic device, is also patented by ECI. In a standard natural gas power generating plant, monitoring equipment within the engine room constantly checks for gas leaks. Should one occur, the system automatically shuts down. While an excellent safety feature in a stationary plant, such a shutdown on a moving vessel could prove disastrous. To assure uninterrupted power flow, ECI's patented Electronic Control Unit automatically switches the fuel mix to pure diesel the instant a shutdown occurs.

Another important aspect of the Olympic project is the opportunity for engineers, scientists and regulatory bodies to work together to set realistic standards for this blossoming new industry. According to SMS's John Pounds, his initial contacts with UCGG representatives have been positive and encouraging. Mr.Pounds said, "The Coast Guard has been given a number of studies over the years. This project will prove the concept and provide a foundation for setting the rules for (LNG) passenger vessels." The year-long test period will include fuel efficiency tests under demanding conditions providing conservative baseline fuel consumption figures. Engine wear testing will include beforeand- after micrometer measurements of all wear parts providing comparisons to manufacturer's expected wear data. Routine maintenance — repair parts, lubricating oil, filters, etc. — will be performed on an as-needed basis over the course of the test period and consumption levels will be compared to the manufacturer's expectations from a diesel fueled system. Once testing is complete, the vessel will continue to serve the industry as a training and research station in the areas of cryogenics, LNG technology, environmental enclosures, and synthetic lubricants, among several other possibilities. Government officials and industry insiders foresee a rebirth in the regional maritime trades if this project proves its worth.

For more information on the system Circle 11 on Reader Service Card