Diesel engines are greener than electric engines? In some cases, yes!


There has been a lot of recent publicity regarding the development of electric vehicles, and in addition, electric propulsion for marine use. Much of what is said highlights the reduced emissions from electric propulsion. It is true: electric engines can be cleaner than diesel or other petroleum engines. However, the media usually neglect an important fact, and that is that electric engines need to be charged somehow. That somehow usually means connecting to the power grid. Depending on where the engine is used, the carbon footprint of that electric engine can be much higher than that of an equivalent diesel engine. In regions where the bulk of electricity is produced by coal or other dirty fuels, that electric engine actually produces up to four times the amount of CO2 as a modern diesel engine.

The diesel fuel in 2015 is not the same as your grandfather’s diesel fuel. Modern diesel fuel is cleaner than ever before. All diesel emissions from vehicle use can be minimized and controlled, depending on the emission type. Right now, in the EU, there is some controversy regarding the fact that even though the introduction of ULSD reduced SOX emissions, there was an increase in particulate matter emissions (PM) and NOX emissions. However, PM can easily be reduced by filtration, and NOX can be reduced by the use of a SCR.

When compared to the use of electric propulsion, on the surface it can seem that the electric engine will produce fewer emissions at lower cost. Yet, when you compare the emissions and cost of charging, with the lower efficiency of electric engines (they are typically larger and heavier than diesels, with lower power output), the advantages of electric become less clear and straightforward. One additional problem that electric engines for marine use have faced is the limited range (electric cars don’t have the same issue as much on land): Limited range means limited places to charge. This fact has restricted the use of electrical engines to hybrids or coastal use.

MarineDiesel is in compliance with all emissions regulations in the EU and North America. Our engines can be used in regions with the strictest emissions standards and regulations (like the polar regions). Our research and development team are constantly modifying and improving the fuel efficiency of our engines, and reducing the emissions they produce.

If you want to learn more, there is an interesting discussion of the subject at





55.74 Kilograms



55.74 Kilograms.

That weight equals:

  1. The weight of an average adult octopus.
  2. 1.3 times the weight of a toilet.
  3. 2/3 of the weight of an adult kangaroo.
  4. 1/4 the weight of a cubic meter of snow.
  5. 4.5 times the weight of a gold bar.
  6. The amount of SOX produced by a MarineDiesel VGT350 over its’ lifespan, using Ultra Low Sulfur Diesel fuel.

SOX is regulated by the EPA in the United States and the EU in Europe. It is regulated because it is a component of acid rain. However, SOX is a different type of emission. Whereas NOX and Co2 are products of the combustion process, and, therefore, produced by the engine, SOX is a product of the fuel itself, and must be refined out of the fuel prior to combustion.

Today, nearly all diesel fuel sold in North America and Europe is Ultra Low Sulfur Diesel, ULSD. No controversy, right? Wrong. The controversy typically arises from the fact that the refining process required for ULSD makes the fuel far more expensive. As we covered a couple of days ago in our posting, 670,000 Liters, small changes in the price of fuel or the amount of fuel consumed have enormous impact on the bottom line. Naturally, the tradeoff is in emissions, and making a cleaner product.

The MarineDiesel VGT Series has been rated to consume ULSD fuel. When the engines burn ULSD, the power and performance is what you expect, and the amount of SOX produced is in full compliance with regulations.






My engine is now non-compliant for emissions. What can I do?



Fortunately, for most MarineDiesel customers, the emissions regulations coming soon will impact large vessels, mostly. The vast majority of our customer vessels are under the 30 ton limit (And our engines are Tier IV, so the expense of ULSD is their biggest concern). However, we still receive some inquiries asking, “What do I do?”

The answer is, unfortunately, complicated. Different emissions are controlled by different methods. SOx, in particular, is often the biggest concern, given the added expense.

With the size of our engines, replacement is often the most cost efficient method. On container ships, with power measured in mW, the story is different. Those engines can cost into the millions of Euro. But, to simplify things:

1. SOx can be removed by scrubbing (using chemical treatment) or ULSD. Those are the options. Scrubbing is not only expensive, but requires a lot of space for the scrubbers themselves. Not really practical when dealing with a 500 hp engine.

2. PM and Smoke can be controlled by filtration.

3. NOx can be controlled by the use of an SCR (Selective Catalytic Reduction). A SCR is, essentially, a mesh in which a chemical (usually urea) “washes” over a catalyst that makes the Nitrogen atoms “stick” to the catalyst. Expensive equipment, though a few MarineDiesel customers have goner this route rather than replacement, usually in situations where our engines are used as auxilliary engines in multi-engine installations.

CO cannot be controlled. CO2 can be controlled by scrubbing, to a certain extent, but on small engines, this is not really practical.







Green Engine Regulations and Development



Whether you agree with the premise of climate change or not, tighter emissions controls are coming, and engine users around the world will soon be forced to ensure that their engines are in compliance with new, stricter emissions regulations. These regulations impact not only the marine market, but all industrial, on road vehicles, and off road vehicles.

The next batch of regulations coming for the marine industry will come into effect in 2016, with further reductions coming in 2020.

On this blog, we have published the following resources for your reference, that we hope you find useful.

Emissions Page

Links Page

Yes, the regulations are complex. Yes, they can be confusing. In general, the following organizations make and enforce the regulations:

  • IMO (Global Shipping)
  • EU (Europe)
  • EPA (USA)
  • CARB (California)

Though there is quite a lot of overlap in the limits, the IMO has tried to at least make the rules somewhat consistent. The specific regulation regarding maritime emissions is known as MARPOL Annex VI.

Generally, there are a number of Emissions Control Areas (ECAs) that govern the maximum amount of emissions that may be emitted. The current ECAs are:

  • North America, including all of the USA, all of Canada, and large parts of the Caribbean
  • Most of Europe (Stricter regulations in areas like Bodensee)
  • The Black Sea
  • The Arctic (Separate treaty)
  • The Antarctic (Separate treaty)

ECA Boundaries

seca map

Additionally, engines are classed based on the tier of environmental regulations with which they comply. All MarineDiesel VGT engines have tested for Tier IV and are awaiting certificate issuance in 2014. Current Tier IV regulations are listed HERE.

If your vessel will operate in any of the ECAs, your engines must be in compliance.

The following emissions are covered under the regulations:

CO2 (Carbon Dioxide)

NOx (Nitrogen Oxide)

PM (Particulate Matter)

CO (Carbon Monoxide)

Smoke (as a percentage of emissions)

The above list of emissions are products of combustion. They can be removed or reduced through engineering, aftermarket treatment options, or a combination of methods. All MarineDiesel VGT engines are in compliance with the above (no after treatment required). Additional regulations apply to:

SOx (Sulphur Oxide)

SOx is a product of the fuel used. All diesel fuel has some level of SOx present. The use of Ultra Low Sulphur Diesel (ULSD) can control SOx emissions.

All of these regulations are controversial to one extent or another, in particular SOx regulations.


The answer is cost. ULSD is over twice the cost of lower grades of diesel (Due to more refining, politics, and other reasons), and since vessel operations have fuel as their biggest operating expense, by far, this has a huge impact on operating costs. In fact, within the ECAs, lower grades of fuel than ULSD are increasingly unavailable.

Our posting tomorrow will address your options if you own a non-compliant, older engine.