Safety and Technology


Battery technology has evolved very quickly, but hybrid and electric marine propulsion is still a relatively young industry. As of today, there are still no commercial systems that can claim to have been in operation for 10 years. Despite this, the economic and environmental advantages of battery storage have meant that there are now dozens of ships operating in hybrid and full electric modes. By recent estimates, Energy Storage Systems (ESS) are now being incorporated in roughly 75% of refits and newbuild vessels around the world.


In 2009 I designed my first lithium batteries for marine applications. These were designed to demonstrate the principal that MW scale ESS could work like traditional propulsion while delivering real commercial value; and there were a lot of doubters. Today, we have evolved not only performance, but safety, integration, cost and risk management to much more predictable levels. The data obtained from constant commercial use of the battery system provided invaluable information that allowed us to evolve and continuously improve our systems.


The Classification Societies and Flag Authorities have also constantly pushed for better and better systems. These agencies have been incorporating powerful risk evaluation tools to ensure operator and passenger safety as system capacities got bigger and bigger.


Operational data and experience have led to significant


60 | The Report • March 2020 • Issue 91


improvements in battery design resulting in improved safety, system life, risk reduction and overall performance. The improved performance of modern marine batteries has also changed the market. Lower system cost means more and more marine verticals are now finding ROI from energy storage. For example, during the formation of the marine ESS industry, tugboats and ferries represented the best commercial applications for energy storage systems. Today we can add cruise ships, oil and gas, offshore and wind farms vessels to an ever-growing list of commercial vessels that are making an ever- greater use of energy storage.


The key considerations of effective battery design start with two principal issues 1) an ESS must be an improvement to the existing methods of operating ships, and 2) the solution has to deliver financial benefits without external support (government grants or tax credit schemes) in order to permanently earn its place as a part of system design.


These are the key questions that we asked when at the design table for our current systems, understanding that they are the key to success. However, we also knew from years of real-world experience that the following criteria are also critically important to long term commercial success:


Safety: we had to be able to effectively eliminate the possibility of thermal runaway in a battery


by Brent Perry


system, otherwise we will never see true acceptability in the markets and growth in system size. This challenge was at the top of our minds in every design decision, and we addressed it by creating our patented CellCoolTM cooling system that effectively removes the risk of thermal runaway.


The principal is very simple; reduce the temperature of the cells at a faster rate than the cell increases in temperature. No matter how hard you work them, with CellCoolTM they will not achieve the temperature required to go into thermal runaway. We worked in cooperation with Classification Societies and Flag Authorities to developed what we all felt were difficult to pass safety tests designed to demonstrate that batteries are inherently safe. We took this to another level and set our own gold standard as safety in the face of spontaneous combustion- the most difficult test that a battery can face.


Even in this very demanding test, we have proven success. Our systems are able to prevent significant damage to the battery (including propagation at the cell level) and ultimately make every system safe to operate. This is done with an inherently simple liquid cooling system. It cannot be achieved with air cooling systems due to the issue of managing transfer of heat with something as energy dense as most lithium chemistries.


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