In 2019, French ferry operator La Méridionale will be testing with Solvay an innovative solution to cut down air pollution from its ships. As a global first, this operation will be closely watched by an industry in need of urgent solutions to curb its emissions.

The severe atmospheric pollution caused by the marine industry has been in the spotlight for some time now. Ships usually burn Heavy Fuel Oil (HFO), which causes massive air pollution due to SOx emissions resulting from the sulfur content of the HFO. As pressure mounts, and in preparation for new stringent regulations from the International Maritime Organization that will kick-in in 2020, it’s high time to clean up those dirty fumes.

Blazing new trails

Solvay’s SOLVAir® Marine solution employs a mineral solution mostly comprising sodium bicarbonate to desulfurize exhaust fumes, a process that has been used in waste incinerators, power stations and many other industrial applications for decades. The company has accumulated extensive know-how with this technology, but is now preparing to adapt it to use on sea. 

Marseille-based La Méridionale, which operates a ferry service to the French island of Corsica, will be the pioneering company to test this solution for the very first time on a vessel. “This is an established, recognized technology on land, but now we have to adapt it to conditions at sea, with the humidity, the movement, the space constraints, etc,” explains Thomas Bauer, Global Project Leader at Solvay’s Soda Ash & Derivatives business unit.

One of La Méridionale’s ships, “Piana”, is currently being equipped with a system comprising storage and handling devices for sorbents and residues as well as a filter, and will begin a six-month testing period in April 2019. As a company particularly concerned with environmental protection issues, the French operator is a logical fit for testing this promising innovation. “We are already in contact with other interested companies,” says Thomas, “so this test is very important for the shipping industry.”

Gas into powder

So how does SOLVAir® Marine work? A sodium-based sorbent is injected as powder into the ship’s exhaust gas downstream of the engine. “The reaction with the sulfur oxides in the exhaust gas produces a sodium sulfate residue, which is then removed by the filter, together with other particles such as soot and micro pollutants, which is a considerable side-benefit,” explains Thomas. “The filter has 99% efficiency for the removal of particles, so the ships don’t spit out that typical black smoke anymore.”

This desulfurizing and filtering system requires the installation of ‘tanktainers’ for the storage of the required quantities of sodium bicarbonate on board, as well as for stocking the resulting residues. This means that on a regular basis, the ship needs to reload on sodium bicarbonate and disembark the residue, which will be treated by Solvay on land. On the Piana, these operations are scheduled to happen once a week.

As for the filter and the additive handling systems, they are to be provided by Austrian plant building company Andritz, the third partner in this project, while the installation of all equipments and piping will  be conducted by La Méridionale on its ship.

Our dry solution is easy and safe, since sodium bicarbonate is so harmless it’s actually edible. And it also offers a significant reduction in particulate emissions.

Thomas Bauer, Global Project Leader, Soda Ash & Derivatives, Solvay

Putting a stopper on the sulfur

Other solutions already exist to reduce pollutant emissions from the marine industry through exhaust gas cleaning. The main one is the so-called ‘wet scrubber’: seawater is used in a scrubber tower for the desulfurization of the exhaust gases. The used wash water is then  released back into the sea (in the case of an ‘open loop’ system) or stored in the ship (which is a ‘closed loop’). 

“The open loop wet scrubber is relatively cheap to operate because seawater is obviously always available,” explains Thomas. “But it means dumping into the sea wastewater that contains sulfates and other components from HFO combustion, such as heavy metals and soot. As the open-loop operating mode is already forbidden in some areas and generally in ports, some ships are equipped with a closed-loop or hybrid mode. Here, alkaline additives such as sodium hydroxide or caustic soda have to be added to the wash water, which then has to be stored on board and disposed of on land for treatment. 

“Our dry solution is much easier and the sorbents are safer to handle, since sodium bicarbonate is so harmless it’s actually edible. Another important difference is that our solution offers a significant reduction in particulate emissions.”

The main argument in favor of open loop wet scrubbers is that they are less expensive to operate, but their environmental impact seems likely to make them a less and less desirable solution. As in many other sectors, environmental pressure on the marine industry has been increasing and will only continue to do so in the future.

Ships using HFO, which is noxious because of its high sulfur content that combustion turns into SO2 and SO3 (the gases responsible for acid rain), are either going to have to shift to low sulfur fuel oil, which is much more expensive, or clean up their exhaust gases. Whether a ship burns less sulfur or removes sulfur oxides from its exhaust gases, the result is the same for the atmosphere.

SOLVAir Marine short infographic

“Our solution is definitely important on the market right now, as sulfur contents in exhaust gases will have to be reduced to 0,5% globally in 2020,” says Thomas. “And in Emission Control Areas (primarily the Baltic, the North Sea and the coasts of USA and Canada) the regulation already enforces 0.1% sulfur since 2015. Moreover, the price gap between low sulfur oil and heavy fuel oil will continue to increase due to rising demand for the former, which means SOLVAir Marine solution will continue to be much more economically appealing.” 

As well as much healthier for the future of our planet.