Is the strategy of IMO for reduction of GHG emissions realistic? IMO is going to be discussing short-term measures starting this May and going into some details. Of course there is also mid-term measures to be discussed later, and long-term measures. The short-term measures, among others, include:

  • strengthening of EEDI and consideration of other indicators of efficiency;
  • Speed Reduction / optimization;
  • Promotion of Alternative fuels.

For the mid-term measures, except for the MBM, there is a paragraph that in effect says ‘make sure that there is an uptake of alternative fuels’. So IMO is putting a lot of faith on Alternative fuels.

If we look at the efficiency indicators, I consider them to be utopian, - we cannot rate ships’ efficiency with a single number. EEDI is a "sea trial" design indicator and should not be used as synonymous to "efficiency' in real waves while operational indicators such as EEOI are nothing more than random number generators. I have covered that in detail in past presentations so very fast we can scratch out the first item,  i.e. by looking at strengthening EEDI and so on,  as being able to deliver any real CO2 reductions.

Speed reduction and optimization

What do we mean by that? If we mean speed limits, then there is problem. I don’t think speed limits are going to be efficient to make any decent reductions in CO2 emissions.  In a study submitted to IMO, we see that if we reduce the speed of the whole fleet by 10, 20 or 30%, you get for every year the equivalent reductions in million of tons CO2. Other studies say that the real CO2 reduction if you reduce the speed, is less than half of what this study says.

But the question is, if you reduce the speed of the whole fleet, how many more ships are you going to need to satisfy world trade demand?  The study itself answers that and it says that ‘for the first year alone, if you reduce the speed by 30%, you are going to need 23% more ships’. For the duration of the study, which is 12 years, you are going to need 37% more ships and 47% more tankers. Some people don’t have a problem building more ships, but my question is how much CO2 will you emit to build these extra ships? According to the study by Professor Psaraftis, Dr. Gratsos, and myself, to build these -otherwise unneeded- new ships you are going to emit nearly 2 billion tons of CO2  in few years. This in order to save 180 million per year as per this study, or 80 million according to more reliable studies ? In addition, if you apply speed limits you have a lot more problems, for example speed limits are not fair to efficient ships. It’s not fair to put the same limit to a ship that has half the consumption than another ship of older design. They don't promote new technology nor good operational practices. The same ship with dirty hull consumes 30% more fuel than an identical clean ship. Yet both, by going at the speed limit, fully comply with the regulation. Concluding on the issue of speed reduction,  speed optimization has good potential, but I would scratch out speed limits.

Alternative fuels

Firstly, I would like to take a look at global warming. Undeniably there is a rise in temperature and my question is what causes it. According to UN IPCC, they have a diagram where the red stuff -Green House Gases- causes it. On the diagram, the blue staff is actually cooling the atmosphere. These are aerosols; these are SOx and NOx which cool the atmosphere. Concerning the temperatures recorded within the last century, there is a very big upward slope since the year 1970, the year that the US applied the "Clean Air Act" for SOx  and other countries followed.  MIT doesn’t think it’s a coincidence. It says that ‘a forthcoming UN regulation, could speed up climate change. Ships have a net cooling effect on the planet. The cooling effect is about 0.25 degrees and for somebody who is trying to stay below 2 degrees that’s a big helping hand, which we are about to take away with the 2020 fuels.’

So let’s have a look at alternative fuels.

Natural Gas

I consider natural gas the mother of all alternative fuels; Almost all of them originate from natural gas. LNG is produced when you clean and cool down natural gas. For every process, you need to put energy in and therefore CO2 out. Just for the liquefaction part alone, you emit 0.4 kg CO2 for every kg of liquid LNG you get from natural gas.  But the big problem of natural gas (which is methane)  is its lifecycle methane slip. Only at the extraction facilities there is a 4% worldwide average leak, with US sites being higher.


Methane is 86 times worse than CO2 in warming the atmosphere on a 20 year time horizon into the future. An engine burning LNG, especially Dual Fuel and Otto, has much worse CO2 equivalent emissions than an engine burning diesel.  The last years there was a 50% increase of CO2 in the atmosphere, but a 250% increase of methane. Now, going back to what causes global warning, I think something that rises 5 times faster and does 86 times the damage is a bigger problem. If you account for the 20 year time frame, methane is responsible for over 80% of global warming. So let's promote LNG for its SOx reduction but it is time to stop claiming it reduces GHG.


95% of the production of hydrogen right now globally, comes from natural gas -using a very carbon intensive process, not from water electrolysis. For the 5% that comes from water electrolysis, you need huge amounts of electricity; about 55 kWh per kg of hydrogen produced. If you take that electricity from a typical city grid, you will emit for every kg of hydrogen you make, 49 kg of CO2. Only if that electricity is from renewable sources, then you can say that the hydrogen you use is clean. So when I hear that ‘my ship is green because it uses hydrogen’, my first question is ‘where did you get that hydrogen from?’


Methanol comes also from natural gas through the same very carbon intensive process, called ‘methane stream reforming.’ For every kg of methanol that you get, you emit 9-12 kg of CO2, in addition to the emissions you have from the production of natural gas. If you use methanol, make sure at least its origin is from bio-gas.


You get ammonia from hydrogen by adding nitrogen to the hydrogen. You get the nitrogen by burning air.  So you have all the hydrogen GHG effects that we talked about before, plus the GHG for the process to make it.


The truth about LPG is that when you burn it on an engine you indeed emit 10-15% less CO2 compared to diesel or fuel. The problem with LPG is that it is not sufficient in enough quantities. You cannot make it, it’s a by-product of natural gas production by 1-5% and a "by-product " of fuel oil refining in the same percentages.


For biofuels I would say don’t ask. There is a great debate whether the CO2 you emit in order to make biofuels, balances out the CO2 reductions of their combustion. And most studies are negative.

So what do we do? Some people say don’t forget nuclear energy. New technology, such as better batteries, synthetic fuels,  is what we need if we are going to make IMO’s goals reality.


Above text is an edited version of Mr. Panos Zachariadis’s presentation during the 2019 GREEN4SEA Conference.

You may view his presentation herebelow:

The views presented hereabove are only those of the author and not necessarily those of  SAFETY4SEA and are for information sharing and discussion  purposes only.

Panos Zachariadis, Technical Director, Atlantic Bulk Carriers Management Ltd

Panos Zachariadis is a Mechanical Engineer (BSc) and Naval Architect (MSE) from the University of Michigan with a 35-year experience in shipping, having served for years as Marine Superintendent in New York, after periods of shipbuilding supervision in Japan and sea service in bulk carriers and oil tankers. He is Technical Director of Atlantic Bulk Carriers since 1997 and a member of the Greek Delegation to IMO since 2004, having contributed to the development of several well-known regulations (e.g. GBS, PSPC, FSA) and the prevention of others (e.g. double hull bulk carriers). In cooperation with major Korean shipyards he has applied numerous energy saving ideas, some of which have become industry standards. He is a member of Technical Committees of several classification societies, UGS and Hellenic Chamber of Shipping, BIMCO Marine Committee, BoD HELMEPA and MARTECMA. He has been honored with the 2011 Efkranti award for his contribution to Greek shipping, the Hellenic Shortsea Shipowners Association 2017 Maritime Personality award and the 2017 Lloyd’s List “Achievement in Safety or Environmental Protection” award.