How to comply with IMO’s 2050 CO2 targets? In SWZ|Maritime's March issue, editor Willem de Jong takes a look at the different options that may help solve this question. Read his article online now.
At this moment in time, ship owners still worry about how to comply with the IMO 2020 Sulphur Regulations and the Ballast Water Management Regulations. Yet, pretty soon they need to consider the consequences of the IMO 2050 CO2 emissions targets. Today, owners have to decide what fossil fuel to use after January 2020, with or without scrubbers. Well before 2050, they have to find fuels and propulsion systems using much less fossil content; an even more difficult task.
IMO GHG Reduction Strategy
In April 2018, the IMO’s Marine Environment Protection Committee (MEPC) adopted a strategy on the reduction of greenhouse gas (GHG) emissions from ships. Total GHG emissions from international shipping should peak as soon as possible and be reduced by at least fifty per cent by 2050 compared to the total amount of these emissions produced in 2008, whilst pursuing efforts towards phasing them out entirely. This strategy is shipping’s answer to the international agreement reached at the 2016 Paris Climate Conference.
In 2008, the total CO2 emissions of shipping amounted to some 900 million tons. This figure – for all international shipping – should at least be reduced to some 450 million tons or less by 2050. A very ambitious goal indeed. The success of this strategy will depend on:
- The conversion of the agreement into legally binding regulations in association with fair and proper enforcement by flag states to ensure compliance – Not an easy task for the IMO and the governments of maritime countries, but essential. Only putting down targets will not work; there have to be regulations and enforcement. Perhaps this process started from 1 January 2019, when vessels became obliged to submit data on their emissions to the IMO. In the European Union such a requirement (the monitoring, reporting and verification scheme (MRV)) was already introduced in 2018 and the first data obtained with that scheme will be published mid-2019.
- The development of the demand for shipping – Will shipping continue to grow and how much? Seaborne trade in the past increased on average with some 3.2 per cent per year. According to Martin Stopford from Clarksons, this percentage could in future go down to 2.2 per cent. Others claim that it could go down more, taking into account changing economic models leading to more local manufacturing, agriculture, et cetera. Transport of fossil fuels may go down, but perhaps transport of various kinds of biomass for the production of low carbon fuels will increase. There could be more transport of grain, rice and other food because of a growing world population. Higher transport costs due to the increasing amount of environmental regulations might also have a damping effect on our transport needs.
The more shipping grows, the more we have to reduce CO2 emissions per ship in order to reach the 2050 target. Stopford’s estimate of shipping growth would result in some 1800 million tons of CO2 emitted in 2050 when nothing would be done to limit carbon emissions. To reach the target of 450 million tons in 2050, with that transport growth assumption, on average, the emissions per ship or transport unit should go down by some 75 per cent. The ship owner association Bimco has also recognised the importance of this issue and has asked the IMO to base the Fourth International IMO Greenhouse Gas Study on realistic economic growth projections and not on some existing estimates claimed to be based on unrealistic projections. - Further improvements in ship energy efficiency – How much can we gain with better hulls, more efficient propulsion equipment, wind assistance, lower speeds? In some areas, we are perhaps nearing the limit of what is possible, in other areas, there may be ample room for further improvements, such as with auxiliary wind propulsion. According to an article in The Naval Architect of November 2018, lowering the speed of large container ships and Panamax tankers could result in a reduction of energy demand and CO2 emissions by approximately 20 to 25 per cent, taking into account realistic weather conditions and the extra tonnage needed for the same transport capacity [1].
- Availability of alternative fuels – Low or zero carbon fuels will be required to substantially lower shipping’s CO2 emissions. These fuels should not just be of the zero or low carbon type when being burned on board, but also when being produced; from well to wake. This means that for the production of these fuels only renewable energy should be used.
Low and Zero Carbon Fuels
This section describes a number of fuels which may potentially help to reach the IMO’s target of fifty per cent less CO2 emissions by 2050. Batteries and methane (LNG or CNG) will not be considered. Although both these “fuels” are attractive for quite a number of applications, for large international deep sea shipping they are not expected to achieve the target of fifty per cent reduction, either because they are not sufficiently low carbon (methane), making them only suitable as an interim fuel, or because they are less suitable for larger ships requiring high power and sailing long distances (batteries). Dimethyl ether (DME) is not discussed either in spite of the good combustion properties claimed for use in diesel engines. Production is still very limited and there is insufficient information available to paint a useful picture of this product.
Low and zero carbon fuels can be produced as power-to-liquid (PTL) and power-to-gas (PTG) fuels from carbon dioxide and water or as biofuels from biomass. PTL and PTG fuels, also called electro fuels, are made by breaking down water into hydrogen and oxygen with the use of electrical energy (electrolysis). The hydrogen together with CO2 from a non-fossil source, is used to produce different types of energy carriers such as methanol and ammonia. In order to get zero carbon fuels, the electricity should come from renewable sources such as hydropower, sun or wind.
Unfortunately, these conversion processes have very low efficiencies. For instance, the overall efficiency of producing hydrogen with electrolysis from water, convert it for storage and transport and convert it to electricity again in a fuel cell, lies in the order of twenty per cent. The efficiencies of the production of ammonia and methanol from renewable energy are similar. A huge increase in the production of renewable electrical energy at an acceptable cost will be required to allow large scale use of such fuels.
Biofuels are made from biomass and include fuels like biodiesel, bio-methanol, bio-ethanol, bio-DME and biogas. Biofuels from the first generation are made from agricultural production otherwise available for food for humans and animals. Biofuels from the second generation are made from for example residues from harvests and forestry and do not compete with agricultural land. It has been calculated that the land required for production of enough biofuels of the first and second generation together for international shipping (300 million tonnes of fuel oil presently being used by shipping per year) would be somewhat larger than five per cent of the current total agricultural land in the world. This is evidently a non-starter, even more so when we think about other powerful industries that would like to use this energy source, such as aviation.
So the first and second generation biofuels will not really help us to achieve the IMO’s target and are only possible for a limited number of ships. More could perhaps be expected from third generation biofuels that do not compete with food production. Yet, these biofuels, for example produced from types of algae such as seaweed, are still in the development phase and it will take years before these may be used at an attractive scale. If ever, because there will also be a hefty price tag connected to this type of fuel. A further drawback of biofuels is that they can cause harmful NOX, CO, PM and black carbon emissions.
The properties of the fuels referred to in this article with those of natural gas (methane) and diesel oil for the sake of comparison.
Methanol
Methanol, also known as methyl-alcohol (CH3OH) is a transparent liquid at room temperature with a boiling point of 65°C and a density of 0.79 kg/l at atmospheric pressure. It is toxic and methanol vapours are heavier than air at ambient temperature and pressure. It has a large flammable range in air and a low flashpoint. Its heating value is approximately half the typical value of diesel fuel. Methanol can be used as a marine fuel in diesel engines with relatively small modifications. It requires additional provisions in view of the low flashpoint (explosion danger) and its corrosive nature. Regulations for application both for conversions and new ships are in place. Recently, a consortium of major Dutch maritime companies has joined forces to look into the feasibility of using methanol as a sustainable alternative bunker fuel under the Green Maritime Methanol project.
Ethanol
Ethanol, also known as ethyl alcohol or alcohol (C2H5OH), is a volatile, flammable, colourless liquid with a boiling point of 78°C and a density of 0.79 kg/l at atmospheric pressure. The energy density is about half of that of heavy fuel oil (HFO), it is corrosive, has a low flashpoint (explosion danger) and cannot be used in diesel engines without additional processing. Regulations for marine application are not yet available.
Ammonia
Ammonia (NH3) is an inorganic compound, used as fertiliser and as such widely stored and transported, either at low temperature (-34°C) or pressurised (10 bar at 20°C). It contains more hydrogen per unit volume than liquid hydrogen, which potentially makes it an attractive fuel. The heating value is half of that of HFO in terms of mass and a third in volume. As a fuel, it can be used in diesel engines, be it with some additional treatment, and it has the potential to be consumed in fuel cells.
As ammonia is less combustible than fossil fuels, the compression ratio needs to be significantly higher. It is toxic and highly corrosive and burns through any component using copper, zinc or an alloy thereof. Green ammonia, that is, ammonia produced by renewable electricity (power to ammonia), would be the best form of ammonia for shipping to comply with the 2050 CO2 target. However, that form of ammonia is also popular for the production of sustainable fertilisers. So far, there is no experience in using ammonia in vessels, but research is ongoing and should lead to demonstration projects. It is considered one of the best potential zero emission solutions for ships.
A graphic presentation of the gravimetric and volumetric densities of some fuel alternatives.
Hydrogen
Hydrogen at ambient conditions is a light, odourless, colourless and non-toxic gas, highly flammable and easily forms explosive mixtures with air. The liquefaction temperature is -253°C at atmospheric pressure. In order to get a meaningful energy density, it is necessary to cryogenically cool hydrogen to make it liquid. Its liquid density is approximately 70 kg/m3, less than one-tenth of a typical hydrocarbon fuel, whereas its heating value is 120 MJ/kg, which is three times more than diesel fuel or natural gas.
It would by no means be easy to build ships that use hydrogen as a fuel. It requires various precautions to deal with the storage system, flammability, cryogenic temperatures, avoidance of leakages, embrittlement behaviour, and so on. As yet, there are no prescriptive requirements for the use of hydrogen as a fuel, but IMO guidelines for the carriage of hydrogen as a cargo do exist. Together with diesel oil, hydrogen may in principle be used in dual-fuel diesel engines, or it can be used in fuel cells, producing electricity for an electric propulsion system. In view of limited fuel cell capacities and other issues, for the time being, hydrogen fuelled propulsion is only possible for small installations. The highest energy output so far installed is 302 kW in a submarine.
Massive Investment in Research and Development
The content above is partly based on information received from CE Delft and Lloyd’s Register, which is very much appreciated. The subjectncovered in this article is very wide ranging. By no means does the article give a complete overview of all the fuels that are currently being developed and which in future should help deep sea shipping to successfully deal with IMO’s strategy to reduce GHG emissions by fifty per cent before 2050.
None of the low or zero carbon fuels mentioned are readily available at this moment and a lot has to be done to make them technically and commercially available by 2030. Taking into account the usual service life of a ship of at least 20 to 25 years, it is evident that timing to achieve the 2050 target is becoming very critical.
The urgency of the matter cannot be better illustrated than by the following statement made on 12 February by Esben Poulsson, Chairman of the International Chamber of Shipping: ‘The ICS Board agreed that the industry cannot achieve the 2050 GHG reduction target by using fossil fuels. […] Over the next decade we are therefore going to require massive investment in research and development of zero CO2 emitting propulsion systems and other technologies which do not exist yet in a form that can be readily applied to international shipping, especially in deep sea trades.’
Please Comment
Your comments on this article are very welcome. It would be great if we could start a useful and informed discussion on fuels and alternative marine power systems in our magazine. Send your response to swz.rotterdam@knvts.nl.
The article above is also available in pdf.
References
- “Speed and Emission Reduction from Ships” by Hans Otto Kristensen; The Naval Architect, September 2018
- “Alternative Fuels: The Present and Future of Containment Systems and Their Impact on the Design and Construction of Ships” by F. Cadenero, E. Fort, L. Blackmore; Lloyd’s Register EMEA; presented in January 2019 at a RINA Conference in London
- “Methanol as a Marine Fuel: The Shipyard Perspective” by Daniel Sahnen from the Methaship project; The Naval Architect, January, 2019
- “C-Job Explores Ammonia’s Fuel Potential”; The Naval Architect, June 2018
