Going Green – Batteries

In the current pathway, global shipping greenhouse gas (GHG) emissions are forecast to rise in this decade and eventually return to 2010 levels by ~2050.

The chart represents the three scenarios for shipping emissions developed by the International Energy Agency (the IEA) and adds in the IMO Strategy targets for emissions reduction. The IEA’s aspirational case (i.e. what governments and companies aspire to do rather than are actually doing – that is the current pathway) closely mirrors the IMO’s 2023 updated strategic direction. The challenge is clear to see - the gap between current actions and the overall ambition to reduce emissions from shipping.

Foundation for Change

The foundation for “going green” is the 2023 IMO Strategy on Reduction of GHG Emissions from Ships which aims to reduce the carbon intensity of international shipping by at least 40% by 2030 and increase the use of zero or near-zero emission fuels to account for 5-10% of the energy used by ships by 2030. The ultimate aspiration of the strategy is to achieve net zero GGH emissions in international shipping by or around 2050. Interim targets include reducing well-to-wake emissions by at least 20% by 2030 and by at least 70% by 2040 versus 2008 baseline. It should be noted that the aspirations are an agreed strategy but many of the mechanisms and rules for achieving these targets are being negotiated at the IMO’s working group.

What is Shipping Doing?

Norwegian Classification Society DNV has been following and reporting on the alternative fuels segment for many years and reports that over 99% of the current operational fleet operates on conventional marine bunker. In terms of the order book, vessels featuring alternative fuels (LNG, LPG, methanol, ammonia and hydrogen) account for ~17% of energy carriers.

Both conventional and alternative fuel segments record vessels with battery energy storage systems.

Drilling Down into Battery Energy Systems

Our earlier chart has established that there are slightly more than 1,000 battery vessels in operation and a further ~550 are currently on order.

Battery energy storage systems (BESSs) deployed in for a variety of reasons:

• Low and zero emission operations, using electricity as an alternative energy carrier to MGO and liquid energy carriers that produce well-to-wake emissions.

• Peak shaving: BESSs support the efficient and optimal loading of internal combustion engines and can help smooth out engine load peaks recorded during short-term additional power requirements.

• Spinning reserve: A BESS can replace combustion engine capacity by providing a spinning reserve, which means they can be an instantaneous back-up system supporting the stable supply of electrical power during critical operations.

Battery hybrid solutions remain popular, where batteries are combined with main internal combustion engines. ~65% of all operational and on order vessels recorded as featuring batteries are hybrid, where the batteries are charged by the main engines. A further ~17% of the segment are plug-in hybrids that feature charging connections that allow for charging in port or at offshore locations. Pure electric vessels that feature only batteries account for ~17% of the segment.

Just over two-thirds of battery vessels are active in Europe and Norway. Batteries have featured in the short-sea shipping segments most suited to battery operations, including ferries, offshore oil & gas and wind support and tugs.

Where Battery Vessels Make Sense

Norway’s installed electrical generation base is ~40 GW, ~85% of which is hydropower, ~13% onshore wind and solar ~1%. Thermal plants account for less than 2% of the installed capacity. Low carbon electricity is available.

With a long coastline and a distributed population, Norway has developed an efficient fjord and coastal ferry network. Since 2023, the government established that ferry tenders will only be awarded to low or zero-emission ferries. The government support has created the confidence for ferry operators to develop charging infrastructure throughout Norway and build plug in hybrid and fully electric vessels, much of which is fully automated and fast charging.

Ferries are considered a comparatively easy segment to abate given their trading patterns. Further, Norway’s exceptionally high proportion of clean electricity production is a clear bonus. However, many segments and countries do not enjoy the same advantages as seen in the ferry segment in Norway and full vessel electrification remains a challenge in these cases. Hybridization though remains and option.

Challenges to Deployment

Battery systems storge electrical energy produced from a range of sources. Given the IMO direction to reduce emissions on a well-to-wake basis, how electricity is produced remains a key challenge to certifying that a vessel is carrying and converting energy that is truly zero or low-emission. Given that the electricity generation base in many countries is a mix of conventional natural gas, oil and coal, nuclear and renewable energy, tracing and certifying the energy stored in a battery system is a key challenge.

Battery systems required to power 100% of vessel operations are generally physically quite large and heavy, impacting on the ship’s design. This is less of a problem in the short sea segment.

Batteries often need frequent charging. It is comparatively easier to plan for 100% battery electric operations for vessels operating on a fixed route or close to charging infrastructure. But where vessels risk being away from charging infrastructure then the need to charge from internal combustion engines increases.

Charging itself is a challenge, where there is currently not one single standard for charging plugs. Another issue is the different charging currents at different ports and offshore charging infrastructure.

Finally, there is a capital cost premium for battery systems, which also generally need replacing after 10-15 years of operations.

Investment in marine battery systems is clearly increasing, whether it be full electrification or hybrid solutions. Challenges remain to address, but solutions will continue to provide opportunities to increase vessel electrification.