There are millions of diesel powered vehicles and stationary engines around the world. Although diesel dual fuel systems have already been developed for specific engines, there are very few universal diesel-CNG systems available to retrofit other engines. Besides being cheaper to operate and reducing dependence on foreign oil, diesel-CNG systems reduce the particulate emissions that have been found to be a health hazard (see CARB School Bus Study). However, although diesel dual fuel systems (diesel-CNG and diesel-LPG) are proven technology, they do not appear to be recognized as alternative fuel systems by the US Department of Energy's AFDC.

For those people having a fleet of diesel engines and readily available supply of natural gas, Technocarb has recently developed the EcoDiesel System, which is a universal, self-calibrating diesel-CNG system that can be installed on any turbocharged engine. Depending upon the amount of diesel fuel purchased annually, a diesel dual fuel system could be a viable option to reduce operating costs, emissions, and dependence on foreign oil.

Tags: CNG, Conversion, Diesel, EcoDiesel, System, Technocarb

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A better dual fuel might be diesel and DME. DME is made from methanol which is made from natural gas. The natural gas can be replaced with renewable methane created by gasification of biomass. DME burns cleanly and can be stored as a liquid at low pressures, much like propane. It would take smaller and less expensive containers than CNG for the same range.
I'm not aware of any commercially available DME injection conversions for diesel engines. A Diesel Dual Fuel System requires an alternative fuel with a high Octane Number and DME instead has a high Cetane Number (~55). A system that switches between diesel and DME (either-or) would require parallel fuel systems and extensive modifications to the engine.

A study of dimethyl ether (DME) as an alternative fuel for diesel e...

Safety considerations of dimethyl ether (DME) as an alternative die...
Whether CNG or DME, extensive modifications must be made. DME can be stored in tanks at lower pressure, thus reducing the costs of the tanks and compressor. It has been used in several applications with success.
From what I can tell, converting an engine to use diesel and DME requires extensive modifications at an OEM level because a second injector must be added to each cylinder in the cylinder head. A diesel-CNG dual fuel system is completely different because it supplies a homogeneous fuel mixture to the cylinders either at injection point in the intake manifold or upstream of the turbocharger. Although DME can be stored in lower-priced tanks compared to CNG, there is NO commercially available, aftermarket DME conversion system at this time. Even if there were, there is no infrastructure in place (comparable to CNG or LPG) to refuel on-road vehicles.

Technocarb's EcoDiesel System can be retrofitted to ANY turbocharged diesel engine. A complete installation by a skilled CNG system installer takes approximately 8-10 hours, including the installation of the CNG cylinders. The delivery of CNG to the engine is controlled by a microprocessor according to a preprogrammed, load-based fuel map.

If you want to continue talking about DME conversions, please feel free to start your own discussion.


Butanol may be used as a fuel in an internal combustion engine. Because its longer hydrocarbon chain causes it to be fairly non-polar, it is more similar to gasoline than it is to ethanol. Butanol has been demonstrated to work in some vehicles designed for use with gasoline without any modification

just because of mention of alternative liquid fuel
What is the point?
I posted this a year ago

MUMBAI: Worried by the rising fuel bill, Indian Railways has now started attempts to convert the conventional diesel engine into a dual fuel engine using Compressed Natural Gas (CNG). With consumption of two million kilolitres of diesel every year, Railways is banking heavily on the experiment with CNG, a proven pollution-free fuel.

The Railways has already started using bio-diesel to cut down on the spiralling fuel bill. In fact, it has decided to set up four bio-diesel plants across the country on its surplus land to manufacture and supply bio-diesel to trains. Now, in its pursuit to control consumption of diesel, it is experimenting with CNG.

CNG is used a fuel by trains in many countries, including the US, Japan and Malaysia.

Indian Railways Organisation for Alternative Fuels (IROAF), an autonomous body under the ministry of railways, has called for tenders from engine manufacturers to collaborate in the engine conversion project. As per the tender, the IROAF wants to convert the conventional engine in a Diesel Power Car (DPC), self propelled coaches, into a dual fuel engine using CNG.

The diesel-powered cars are used in trains plying on short routes up to 200 kms. Instead of using a conventional locomotive, these trains have two diesel-powered cars after every five coaches to push the rake forward.

R Srivastava, Chief Mechanical Engineer (CME) at IROAF, said the attempt is to fit in a CNG tank and cylinders adjacent to the diesel tank under the engine of the DPC. "We would like to run the diesel power car using 70% diesel and rest using CNG. This proportion can be gradually increased if the technology is successful," he said.

Officials in the railway ministry said conversion of the engine in a DPC is the first step towards saving fuel. The next step is to try and convert the engine in a locomotive used in express trains.

Meanwhile, Srivastava said IROAF is looking at both ignition and fumigation technologies for conversion to CNG.

While the ignition technology allows using maximum of 30 % CNG along with diesel, the fumigation technique can ensure that the green gas can be used upto 90 %, entailing a huge saving for railways. "But the fumigation technology is not available with too many engine manufacturers. However, it is not impossible to get the technique," said Srivastava.
The technique is not impossible, for it has been done. The power loss is too dramatic and the popularity of spending money to lose power is not high on people's lists. In order for change to happen it requires the desire and not just the regulation to adopt change. What Frank is talking about is REAL, ACCEPTED and is in use right now. These key points make it viable and people will use it. Offer something people want and they will buy it, force it on them and they will relucktanly take it but always look for ways to defeat it. Another definition would be "human".

CNG fumigation systems for diesel engines are real and do work, it is also not a new idea but the emerging technology is. The magnitude of the performance realized whether it be power, economy, or reduced emissions is dependent on the level of technology. There are a number of systems available that are fairly economical to purchase, simplistic in their design, however the consistancy of the performance can be less than desirable. Systems that incorporate controllers with various sensors have a better handle on sustaining repeatable levels of performance, again those being power, economy and emissions ( the order of the above list has no significance by the way).

You can also bet that these systems will become regulated in some degree by EPA and CARB to ensure sustained consistancy in performance. One main objective will be anti-tampering with said systems as well, which cannot be achieved with simpler technologies. I did read up on the Technocarb system mentioned by Frank and it seems that they have hit the nail on the head in this regard.

I should point out that their system is also designed to work with LPG so this can be a more economical option. What should be considered is the cost of the fuel. A CNG system may cost more because of the higher tank cost, however may be practical in the long run if CNG prices are low enough. The questions that should be asked are:

1 - what end result do you require - reduced emissons, better economy etc.

2 - what is the distance that the vehicle will travel each year

3 - what fueling infrastures are in place

4 - what is the fuel cost difference

each fuel will achieve similar results, although you may uses 10% - 15% more CNG that LPG for the same result.

The main overwhelming reason to do a conversion, other than your concience questioning how much you are hurting the environment, will be the regulations placed on particulate matter from diesel engines which is in the gun sights of both EPA and CARB. Many climate scientists also balme particulate matter for being the major reason for polar melting ( and not green house gasses). I do not wish to discuss that one here though as it will take away from the original idea of this post started by Frank.

Although this may become regulation, this type of technology can help reduce operation costs so it is favorable in the eyes of fleet operators. Selling people on using this type of technology won't be as hard a sell as some straight emission reduction regulations that only cost money and don't help recover it.


There are a lot of links on this.


Type in "CNG diesel dual fuel" and you get lots of them.
Diesel-CNG is not a new concept and there are several companies making these systems for specific vehicles. The EcoDiesel System is economical UNIVERSAL system that can be installed on ANY diesel engine.

Incidentally, Technocarb makes several model-specific CNG conversions. The only difference between a universal system and a model-specific system is that the model-specific kit contains model-specific brackets, fuel system components, and programming so that it works perfectly out of the box. Universal systems require custom bracket fabrication and software configuration by the installer.

Also, it is the CNG conversions for gasoline engines that have lower power. Diesel-CNG conversions actually gain power because the additional fuel supplied makes use of the excess oxygen already in the combustion chamber.
This article shows the DME and diesel can be used.
Discussions that exclude other options do no one any favors.
I'm not sure why you want to continue comparing R&D projects with commercially available products. DME may very well be a viable alternative fuel for diesel engines but no-one can convert their vehicles with a DME system at this time. Even if such a system were available, there is no refueling infrastructure in place for it yet. Maybe diesel-CNG isn't perfect but you can buy an off-the-shelf system today.

I've started a new Diesel-DME discussion for you. I think that might be a more suitable place to promote this concept.


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