Shipping poses a particular challenge from an energy transition point of view. The maritime transportation sector emits more than a billion tons of carbon dioxide a year and accounts for around 2.5% of the world’s greenhouse gas emissions a year, set to increase by up to 250% by 2050.
Unlike activities such as electricity generation, the carbon emissions from shipping are hard to avoid. Maritime transport belongs to a group of sectors, also including aviation and cement production, that cannot easily switch to renewable power generation to reduce carbon emissions.
Sailboats aside, maritime transport requires fuel. Traditionally, this has been obtained from the heaviest fractions of oil, which are highly polluting.
Concerns over sulfur emissions have led the International Maritime Organization to enforce reductions that have often required the use of scrubbers.
However, dealing with shipping’s carbon footprint will take a move away from bunker fuel—and batteries could play a key role, in at least two ways. The first is to allow for full-scale electrification of certain types of maritime transport.
Ships that travel short distances, for instance on ferry routes, can effectively become carbon neutral by using batteries for motive power and recharging them with renewable energy when at port.
This strategy is already being embraced by operators such as Washington State Ferries, which runs the world’s second-largest ferry system and is Washington’s biggest diesel polluter.
Last year, the company began an electrification program that will ultimately see it reducing carbon emissions from the consumption of 20 million gallons of diesel across a 22-vessel fleet. A spokesman for the ferry company has said the move will save “millions of dollars annually.”
Because ferry electrification can deliver up to 100% fuel savings today, a study by DNV GL for the European Maritime Safety Agency in May 2020 calculated batteries could achieve a payback time of less than five years for the sector.
Ferry electrification does not only need vessels to be equipped with battery systems, but also will likely require quayside batteries to optimize recharging times since smaller ports may lack the grid infrastructure for rapid charging.
Furthermore, the energy storage requirements for ferry electrification are likely to be significant. Although the ferry industry might not seem like a major transportation sector, in reality it is as big as commercial aviation, transporting more than 2.1 billion people a year.
For ocean-going vessels, meanwhile, batteries could still play an important part in decarbonization even though long-term solutions will require the use of alternative fuels such as biofuels, green hydrogen or ammonia.
The deployment of these alternative fuels is still in its infancy and there is no consensus on which fuel might become the ultimate replacement for bunker crude.
Even once this consensus emerges, it will take many years to convert existing vessels and refueling infrastructure to the new source of power. Hence, the current focus for decarbonization efforts is to try to reduce emissions by improving engine efficiency, with battery storage emerging as a key enabler.
In particular, there is growing interest in combing battery systems with existing propulsion units to optimize energy use onboard vessels. While fossil-fuel generation takes care of forward propulsion, batteries can supplement or replace auxiliary engines used for electric loads and maneuvering.
One review of onboard fossil-fuel and energy storage system (ESS)-based microgrids has found there are significant benefits to integrating batteries into existing power units.
“It is observed that ESS can be useful to flatten the vessel’s load profile, to facilitate starting and stopping of generators, and reduces the number of online prime movers,” say the authors. “Moreover, it helps the prime movers to run at their optimal fuel-consumption efficient point.”
In addition, says the study: “ESS in peak-shaving applications further economizes the fuel consumption and therefore results in a reduction of emissions by reducing the number of online generators.”
Lithium-ion battery systems are the ESS of choice for the shipping industry, the study notes. Typically, the systems are deployed as fully integrated, containerized units comprising batteries, power converters, controls, cooling and ventilation, and fire detection and suppression measures.
The popularity of these lithium-ion systems likely has several reasons, including:
- Lithium-ion battery systems are relatively inexpensive and their cost is continuing to fall rapidly compared to other forms of energy storage.
- The batteries come with long-term performance guarantees and chemistries such as lithium iron phosphate have high levels of safety.
- Container-based lithium-ion battery systems are easy to stow on deck and can be integrated into onboard microgrids without difficulty.
- Lithium-ion systems are easy to procure and highly scalable, making it easy to adapt them to all vessels within a fleet.
- There is already a strong track record and knowledge base of deploying lithium-ion systems in the shipping industry.
- The technology is mature and bankable.
The fuel reductions that battery systems can deliver for ocean-going ships will vary greatly on the type of vessel and how it is used. Pacific Green Technologies Group estimates fuel savings of anything from zero with some deep-sea or bulk vessels to 100% for all-electric tugboats.
However, since many ocean-going vessels have considerable fuel requirements, even modest reductions in consumption can lead to rapid payback times for battery systems.
To take some examples, DNV GL says the payback time for batteries can be as little as a year for offshore drilling units or bulk vessels with cranes. Shuttle tankers, traditional tugboats and offshore supply and wind farm support vessels can all cover the cost of batteries within a couple of years.
Since fuel costs represent a significant portion of vessel operating costs, the implication is that many shipping operators could benefit from an investment in battery storage today even without wanting to cut the emissions from their fleets.
Furthermore, the business case for battery storage is only likely to improve as authorities seek to impose low-carbon policies that put a higher price on emissions.
At Pacific Green Technologies Group, we combine a heritage in vessel emissions reduction with the latest technology know-how in energy storage, so contact us now to find out how you can benefit from this growing trend.