Electrifying the Future

How batteries will super-charge the energy transition within the marine market


Gavin Forward CEng, Senior Project Manager

Owners and Operators are looking for new alternative fuels and technologies for greener shipping and to improve vessel efficiency whilst reducing their operating costs. Several drivers are at work:

  • Imminent IMO requirements for reducing global fleet emissions by 2030,
  • Introduction of the EU’s Emission Trading Scheme (ETS) for carbon taxes
  • and the rising cost of traditional bunkers,

Battery hybrid systems are now seen as proven technology offering a cost-effective, near-term solution for many vessel types, from new build and through retrofitting. These systems have an important role in the energy transition and the decarbonisation of the world fleet, particularly in the offshore, short sea and inland shipping sectors where the biggest benefits can be realised. Battery hybrid systems are seen as a steppingstone to fully electric shipping, now becoming a reality in some short sea markets.

Energy storage systems

Numerous Battery hybrid / Energy Storage Systems (ESS) exist on the market, from containerised systems to fully integrated. Each is specifically designed for the intended vessel and operational profile. An ESS can be used to replace and/or supplement existing diesel engines onboard a vessel. The ESS can supply instantaneous power to the vessel’s grid, peak shaving engine loads and allowing for the remaining diesel engines to run at their optimal load,. The result is better fuel efficiency, reduced emissions (NOx, SO2 & CO2) and smoother load variations for improved operations. These systems can also be used to deliver short-term emergency power back up in the event of an engine failure. Larger systems allow for longer periods of emission free sailing. Battery hybrid systems typically result in 15% to 20% fuel savings1 with resultant emission reductions. They have the added benefits of reduced running hours and subsequent maintenance costs for the remaining diesel engines. Overall hybridisation delivers a safer and more responsive vessel.

Hybrid Market

Adoption of battery hybrid technology within the marine sector has seen rapid grown in recent years. This has been driven by several factors, most notably the increase in fuel prices and more stringent requirements for reduced emissions set by IMO. Its guidelines target decarbonisation and reduction in Green House Gases (GHG) of 40% by 2030 and 50% by 2050. Domestic policies are also driving this change, with Norway setting its emission limits at 50% by 2030 whilst also placing a ban on the use of Diesel fuel from 2026 within its UNESCO Fjords. In Asia, Japan is targets for Net-Zero greenhouse gas emissions by 2050 within the shipping industry. Indirectly shipowners are being influenced to switch to more efficient operations, with major financial institutions making it clear that there is a benefit in being able to demonstrate future environmental performance when looking for newbuild vessel financing and chartering. Many operators are now seeing the benefits of cleaner vessel operations whilst being able to market their ‘green’ credentials.

Considerable developments have been achieved in lithium-Ion battery technologies over the last ten years, and when combined with the substantial fall in the unit price of batteries (60%-70% in the last four years)1, this technology has become of increased commercial viability within shipping. This downward trend in battery price is likely to continue, with predictions of up to 50% price reductions when compared to current market levels by 20301. Battery hybrid systems have a relatively low cost of investment and minimal footprint when compared to other solutions with comparative emission reductions such as an LNG fuel system, which require integration of complex double walled pipework and large cryogenic storage tanks.

The uptake of hybrid technology can be seen across almost all the maritime sectors to some degree, with the largest adopters to date being in the ‘offshore & renewables’ segment. The operation of high powered dynamically positioned (DP) vessels requiring increased levels of redundancy can benefit from significant fuel savings in this market. In addition, higher levels of investment have been available in this sector and many energy firms have been pledging to reduce emissions within their value chain.


The ‘Ferries’ segment has witnessed large scale hybrid adoption, with over 80 hybrid ferries already in operation and a strong order book for new vessels. The majority of these are operating on short sea routes within Scandinavia, particularly Norway, where there has been a significant regulatory push for reduced emission in recent years. The cargo market has seen a slow move to hybrid technology, with no large uptake across the global fleet. Cargo ships generally operate slow and medium speed main engines on deep sea routes where there is currently limited potential for a good return on investment for hybridisation. To date, adoption has been seen on more specialised cargo ships and when combined with LNG fuel where hybrid systems can optimise its application. However, recently several Scandinavian owners have placed substantial orders for battery hybrid general cargo coasters in the 5000 DWT range where the benefits of these systems are more attractive.

In addition to the hybrid Fleet already operating and the large order book for new hybrid vessels, there are also a considerable number of planned conversions. Several operators in the cruise, offshore & renewable markets have declared major fleet investments in battery conversions over the next five years.

Electric Fleet

Pure electric shipping is not applicable to all vessels and sectors due to the high-power demands over long periods. However, it has seen substantial growth in the short sea ferry market over recent years, with over 30 fully electric ferries currently in operation and a further 37 on order as of April 2022. These vessels are predominantly operating within Norway, where there has been considerable investment in port charging infrastructure to align with the country’s goals for a full electrification of this sector by 2025. Electric shipping will play a key role in the development of autonomous short sea shipping, currently in its infancy, with the first fully electric autonomous vessel ‘Yara Birkeland’ completed at the end of 2021.

In summary

The anticipated future developments in both hybrid technology & battery density will allow for wider application of energy storage systems across the global fleet. The predicted fall in battery unit prices, the continued instability of world diesel bunker prices and the levying of CO2 taxes will see these systems having increased commercial viability. Energy storage systems will also play an important role in the role out of alternative marine fuels, allowing an easier shift to more modular fuel systems in the future. This can be seen with the adoption for Hydrogen Fuel cells combined with an ESS, where the full benefits of a Diesel Electric/Battery system can be realised whilst producing Zero emissions. Operators and owners will be compelled to adopt new technologies to comply with the increasing number of countries, regions and ports imposing specific emission reduction requirements on seaborne trade within their jurisdiction. Norway can be seen as one of the world leaders for emission reductions in the maritime sector where energy storage systems have already played a key role in meeting their environmental obligations. International collaboration will be required to align emission reduction limits for the world fleet, in addition to further investments incentives for adopting this new technology if the rest of the world is to follow Norway’s lead.

Houlder Ltd

Houlder has a proven track record on the Design and Engineering associated with integration of battery hybrid systems, including new build hybrid ferries & research vessels, fully electric ferries and assistance with the conversion of specialised offshore vessels. In addition to several key hybridisation projects, Houlder has conducted various energy efficiency studies for our clients and have completed several preliminary battery hybrid concept conversion FEED studies for various vessel types.

Houlder can offer a flexible design and engineering package to suit our clients’ requirements, drawing on a wealth of in house knowledge and expertise’s, including but not limited to piping design, electrical system & automation design, marine system and machinery design, structural engineering, 3D modelling, naval architecture, project management,  site survey, laser scanning and marine operational experience across all maritime sectors.

Read about Houlder’s Battery Hybrid Capabilities here: Houlder Capabilities Statement – Battery Hybrid

Published July 2022. References: 1DNVGL



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