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Aug 25

Can you convert a diesel truck to run on natural gas?

Posted on August 25, 2017 at 8:13 AM by Andy Tudhope

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Yes, you can! Western Washington Clean Cities is currently working with Omnitek Engineering Inc., American Strategic Group, and Adtra Inc. to demonstrate the conversion of diesel truck engines to compressed natural gas (CNG). Through a pilot project funded by the Port of Seattle, Omnitek is developing new conversion systems, taking them through the U.S. Environmental Protection Agency’s (EPA) alternative fuel certification process, and deploying several demonstration trucks in container hauling service at the Port of Seattle.

Converting a truck from diesel power to CNG has numerous benefits. Due to lower fuel costs, switching to CNG saves fleets money and can offer a quick payback. Natural gas-fueled trucks produce less emissions, are less prone to breakdowns, and quieter for both truck operators and their surroundings – an added benefit. Additionally, natural gas can be sourced domestically, which benefits all of us.

For the pilot project, Omnitek developed conversion products for the Detroit Diesel Series 60 engines and the Cat C15 series engines. These systems are emission-tested and have passed the EPA certification process. Soon four of these trucks will be operating in Puget Sound-area fleets.


Two kinds of natural gas conversions

Unlike other diesel conversion systems that “piggyback” on an existing diesel engine, Omnitek converts the diesel engine to a spark-ignition engine, which allows them to completely switch to natural gas.  These systems are referred to as dedicated natural gas conversions.

The alternative approach, known as dual fuel systems, retains the diesel fuel system to act as a liquid spark plug. Dual fuel trucks start on diesel fuel and continue to use a reduced amount of diesel fuel throughout their duty cycles. As the truck begins to pull a load, natural gas is injected along with the diesel fuel to propel the truck, significantly reducing the diesel used by the truck.

Dual fuel systems are easier to install than dedicated conversion systems but are not as effective in reducing emissions and diesel fuel use.

EPA-certified conversion systems are now available for a wide variety of engine platforms in both dedicated and dual fuel configurations. The EPA certifications for the conversion products are specific to the engine type and vintage, but a large number of manufacturers have some of their engines covered under one or more natural gas conversion type.



How do I convert my truck to run on natural gas?

Today, glider trucks are the most commonly-seen example of a natural gas conversion. Most of the time, the glider truck is converted to a dedicated or dual fuel natural gas engine prior to the customer taking delivery. It is also possible to convert these trucks after they are in service.

Dedicated natural gas conversions are most cost-effective if they are installed when an engine is due for an overhaul or major repair. Installing the dedicated system can be more involved, so undertaking the engine conversion at a time when the truck already needs to be serviced will reduce labor costs. Bundling the conversion cost is just like having your water pump replaced when your car is due for a timing belt replacement because the added cost is low compared to having to replace the water pump down the road.

Dual fuel systems can be added at any time in a vehicle’s life. Conversion kits are certified for different vintages of vehicles, so some kits can only be installed on relatively low mileage vehicles, and others are prohibited for installation until a vehicle is considered beyond its useful life. These limitations are related to how a conversion company approaches the process of certifying their conversion system with the EPA.

For more information on CNG conversions, contact Clean Cities for assistance – we can review the conversion products that are certified for your engine types.