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Marine Engineering - An Independent Approach

In the last 20 years, GHG (greenhouse gas) emissions from land-based modes of transport have continued to decrease, however the same cannot be said for international shipping.

14 April 2015

Defence and Security

Marine Engineering - An Independent Approach

In fact, the increase in the global trading of goods has led to a rise in emissions which is placing the International Maritime Organization (IMO) under greater scrutiny and pressure to introduce measures which will help to limit or reduce the shipping industry's emissions of CO2.

John Buckingham, Chief Mechanical Engineer of BMT Defence Services Ltd discusses how the maritime industry can evolve and become more environmentally friendly, through improved efficiency at an engineering level. He goes on to outline how improvements in current technology and the implementation of new technology can be deployed, to deliver the balanced situation of reduced emissions and fuel consumption.

According to the IMO's 2009 Second GHG Study, international shipping is estimated to have emitted 870 million tonnes (mt) of CO2 in 2007, no more than approximately 2.7% of the global total for that year. That said, projections show that, by 2050, those emissions could grow by a factor of 2 to 3 if no regulations to stem them are enacted. Furthermore, in the UK specifically, it was highlighted in a report by the Department for Environment, Food and Rural Affairs (DEFRA) that CO2 emissions associated with imported goods and services consumed in the UK accounted for around a quarter of the carbon dioxide footprint in 1990 (166 mt CO2, 27 per cent). By 2009 their share had increased to just under half (331 mt CO2, 45 per cent).

These figures clearly show we are importing more goods and services by sea, therefore understanding the importance of shipping and its contribution to CO2 and taking remedial action has never been so important. Successfully addressing climate change will be far from easy; but failing to do so have consequences for us all. For some time now the IMO has been pursuing the limitation and reduction of GHG emissions from international shipping through a package of technical and operational measures to improve energy efficiency and reduce GHG emissions from international shipping. Such measures comprise the Energy Efficiency Design Index for new ships (EEDI), the Ship Energy Efficiency Management Plan (SEEMP) and the Energy Efficiency Operational Indicator (EEOI). 

There is however, still widespread disagreement over the suitability of the EEDI to rate new ship designs and how they should be compared with best practice. Specifically, the faster ships such as Ro-Ro and containerships would be penalised the most if the situation was to stay as it is. The EEDI certainly continues to be a disputed index for designers as it is contested that it cannot form the basis of a legally binding design objective because it is unable to consider the commercial aspects of ship operations. The EEOI however, uses actual data from ship operators to identify the same metric which allows much greater accuracy than that of the EEDI. 

Furthermore, there is currently an oversupply of vessels due to the significant amount of vessels which were built between 2000 and 2008. Couple this with the global financial crisis and we now have overcapacity which will endure for some time to come. This means that we are unlikely to have the chance, in the near future, to transform the fleet of new ships or, introduce new technologies which will help to reduce CO2. As such the EEOI will be become more relevant than the EEDI moving forward, in order for the industry to look at ways of improving existing ships and their current operating indicators.

The three IMO measures are designed to bring about a 30% reduction in CO2 emissions from new ships by 2025. However, the consensus is that they are unlikely to fully offset the emissions due to the future growth of shipping. Between 1990 and 2007 global international shipping CO2 emissions grew on average by 3.7% p.a. With the EU watching the IMO closely, additional measures such as carbon taxes may yet be applied if the IMO measures do not have the desired effect.

The widespread recognition that shipping emissions will increase, whilst other transport sources are in decline places greater political and moral pressure on the maritime industry as a whole, to take action. Introducing energy efficient measures to existing fleet can be costly and will often require additional equipment and on-board support and training, therefore the ROI needs to be realised and the financial risk minimised, for it to appear as an attractive option for ship-owners.

With this challenge in mind, ship-owners and operators can look at improving efficiency at an engineering level through on-board husbandry, maintaining equipment more effectively and ensuring that machinery is being used at the optimum loads. For example, the judicious loading of diesel generation sets all the way through to variable speed pumps - all of which can enhance the efficient running of the ship. Of course this can only be made possible if the crew are sufficiently informed and are given the opportunity to better understand the impact these efficiencies can have.

As part of a multi-disciplinary consortium made up of researchers from five universities and international industrial partners such as Lloyd's Register, Shell and Rolls-Royce, BMT is playing an important role in supporting the work packages for the Low Carbon Shipping consortium research project. The three year project which aims to find feasible ways to limit the environmental impact of carbon emissions from the world's shipping systems, is currently researching technologies for low carbon shipping (including innovation in retrofit solutions), as well as energy efficient ship operations, much of which will include human factors.

Improvements to current technology can also be made. For example, the extraction of waste heat from engine exhausts using a turbo-generator is an area which has already had success with heavy duty land vehicles. Energy recovery methods such as this can allow for the effective use of fuel in the engine to be decreased by 12% or more and is widely used in ships such as the Queen Mary 2 and in offshore applications. The adoption of electric gearboxes to allow engines and propellers to both operate at their most efficient region are also strong candidates for the maritime environment as are contra-rotating propellers, Mewis ducts and air lubrication which have all been shown to offer benefits to specific ships for particular speeds and duties. Technologies such as these can collectively provide fuel and emission savings in the region of 10 to 15%.

New technologies also have a part to play and modern batteries could play a significant role, especially within the ferry industry where coastal emissions are important. The Scottish Government for example, is making progress in this area where they are looking at using energy from the wind turbines that are situated off the west coast to drive their new ferries.

The ability to carry out an independent technology assessment and effectively match the right technology to a particular ship is something that BMT has been doing for over ten years. By conducting power and propulsion studies for a wide range of commercial and naval clients, BMT can help customers to improve power generation and propulsion efficiency and promote energy conservation. To achieve energy efficient power and propulsion requires a robust assessment of the ship, its operating profile and the technology options available. By carrying out this assessment, BMT is able to provide an independent viewpoint on the technical benefits whilst providing valid reasons for owners and operators to either consider or disregard certain technologies. This allows for effective decisions to be made to improve machinery and equipment efficiencies.

This approach was most recently adopted for the Royal Navy's MARS (Military Afloat Reach and Sustainability) Tanker project which saw BMT's AEGIR® design winning the contract. This project required an energy efficient approach and we were assessed on whole life costs with fuel consumption playing a major part. This in turn, allowed us to carry out a technology assessment and identify the most energy efficient solution.

Increasingly, commercial ships are becoming much more specialised and complex. Add to that, the fact that there are over 150 different energy saving technologies of varying degrees of maturity, ship-owners and operators looking to identify the technologies which have the most merit face an unenviable task. Each technology needs to be considered in conjunction with the specific operating profile of the ship. By carrying out an independent technical assessment, BMT is able to quickly assess and provide the necessary information so that ship owners and operators can realise the benefits and make a valuable contribution to reducing the shipping industry's emissions

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