How is Transportation Trends That Drive New Thinking and Designs Technologies for Marine?

Recent environmental regulations are strongly impacting the international marine shipping industry.

The International Maritime Organization (IMO) regulates international shipping and its International Convention for the Prevention of Pollution from Ships (“MARPOL”) has now been signed by 156 flag states, which represent 99.4% of the world’s shipping tonnage.

In April 2018, the IMO adopted a strategy for reducing greenhouse gas emissions from international shipping, the first global climate framework for this industry.It covers both new and existing oceangoing vessels. Compared with 2008 levels, it sets a 40% greenhouse gas (GHG) reduction target for carbon intensity by 2030 and a reduction by at least 50% by 2050. This presents both great challenges and opportunities for innovation.

One of most unique new propulsion systems is an ancient one: wind. A Swedish shipbuilder has developed a wind-powered prototype of a 35,000-ton oceangoing car carrier. It has vertical telescopic sails made of steel and composite materials, which are the tallest sails ever constructed. Able to cross the Atlantic in 12 days carrying 7,000 cars, the ship will emit 90% less CO2 than conventional car carriers. The full-size version is scheduled to launch in 2024, according to an October 2020 CNN travel article.

The IMO has also set a new a cap on the sulfur content of fuel used on most commercial ships to further cut sulfur oxide (SOx) emissions, a major environmental pollutant. Since 2012, the maximum limit had been 3.5% sulfur content but the new cap, effective January 1, 2020, is 0.5%. There are several ways for ships to meet these requirements in the short term, such as switching to more expensive low-carbon and low-sulfur fossil fuels. Another option currently being used is onboard exhaust gas cleaning systems (EGCS) or “scrubbers” that remove harmful pollutants from burning higher carbon fuels before they are released into the air. Other measures proposed by the IMO to improve fuel efficiency, thus lowering ships’ carbon emissions, include energy efficient design improvements of new vessels, improved operational efficiency, and vessel speed reduction.

An increasing number of large ships, including container ships and cruise ships, are being built to run on liquified natural gas, which can reduce CO2 emissions by 25-30% and SOx by up to 90% compared with conventional heavy fuel oil and marine diesel oil.

LNG retrofits of existing vessels, however, are costly. LNG fuel requires onboard cryogenic storage tanks that smaller vessels cannot accommodate. The consensus is that in the near term, many ships with large bore diesel engines will use “dual fuels,” both LNG and conventional marine fuels, to satisfy environmental regulations. One global oil company predicts that by 2040, 12% of all shipping fuel will be LNG. In addition, some European companies are already working to develop future propulsion systems that run on hydrogen- and ammoniabased marine fuels to meet 2050 emissions limits.

Another growing environmental issue for ships relates to their ballast water. This is seawater pumped into and out of storage tanks to compensate for weight changes in the cargo, fuel, and water they carry.

Ballast reduces stress on the hull and provides stability when ships are at sea. Unfortunately, this practice has led to the uptake of harmful aquatic organisms, including invasive species, and their subsequent discharge into marine environments elsewhere in the world. In 2017, a Convention of the International Maritime Organization went into effect requiring all international seagoing ships to exchange any ballast water taken in at their last port with fresh seawater, at least 200 miles from shore. A new, stricter Convention is scheduled to go into effect in 2024 that will require these ships to either use an onboard ballast water treatment system or to discharge their ballast water at an approved facility on shore. All oceangoing cargo vessels, military ships, cruise ships, and many smaller ships and large yachts have onboard systems that convert seawater into potable water.

“In the old days, vessels that were out to sea for extended periods filled their large water storage tanks in port before sailing. Now, thanks to water filtration technology, ships and pleasure craft alike are improving their sustainability and safety by making their own fresh water ondemand,” says Paul Kamel, water purification Product Manager II with Parker. “They have an endless supply of safe, fresh water and can free up space and weight of water storage for other uses.” Marine desalination systems rely on one of two basic technologies: thermal distillation or reverse osmosis (RO). A thermal distillation system boils seawater using the ship’s waste steam and heat from its engines. The steam then condenses into distilled purified water, leaving behind the salt and other impurities.

Reverse osmosis, instead of using heat, uses energy to pump seawater through semi-permeable membranes, which filters out everything but pure water. Because thermal distillation requires very large diesel engines to supply the heat needed, vessels with smaller engines use reverse osmosis to generate clean water. Many large ships, however, have both types of systems. There is a trend toward smaller cruise ships choosing reverse osmosis over thermal systems for both new ships and retrofits. New RO systems use more compact equipment so have a smaller footprint. They also are easy to install and maintain and they require less energy that earlier RO systems.

Rapidly growing global demand for clean water is pushing engineers to develop improved desalination technologies that will deliver higher performance and lower costs. Kamel says this technology is finding land-based applications, such as large containerized systems used for natural disaster relief, and compact, easily transportable systems used by the military and first responders on missions in remote locales where fresh water isn’t readily available. Marine systems will benefit because both land-based and ship-based systems use the same two basic technologies. Research is underway on new membrane materials, such as graphene, carbon nanotubes, and mixed matrix materials. Other research is exploring chemical methods of extracting salt, and thermal systems powered by renewable energy.