Ocean-Going Vessels Going Green? Currently, over 866 million tons per year of CO2, or 2.4% of the world’s total, come from maritime sources. A report to the European Parliament predicts that maritime emission will account for up to 17% of total global greenhouse gas produced by 2050. In the US market, ships used a 150,000 billion BTU of power, corresponding to about 2 billion gallons of ethanol in 2012. These emissions must be curtailed to achieve the global greenhouse gas reduction targets set in recent international agreements.
The importance of maritime emissions have led to a global effort to find approaches to reduce them that include changes in ship design and propulsion systems. This effort has also included testing a wide variety of biofuels. Yet the question of how biofuels and other renewables fit into this reduction effort remains to be determined.
Are Biofuels Useful In Maritime Applications?
New emission standards have opened the door to serious shifts to new maritime technologies and fuels. Environmental regulations limiting SOx and NOx emissions within 200 miles of coastlines are forcing a short-term shift away from the currently used heavy fuel oil to alternatives. This shift may be reversed when more ships are retrofitted with emission control devices. These devices will add to the cost of the continued use of heavy fuel oil. There is an increase in the maritime shipping of liquid natural gas and methanol which is funding the construction of new port infrastructure capable of handling these materials. Concerns about global warming are also affecting corporate and government strategies.
Biofuels face some significant obstacles as a maritime fuel replacement. Heavy fuel oil is traditionally 20-30% less expensive than gasoline or diesel fuels. The energy density of biofuels is often significantly lower than current fuels. The volumes required are also an issue. Fueling a single large ship for about 10 days of sailing requires over 350,000 gallons of fuel. This presents significant issues when evaluating new fuel sources. Large quantities of fuel are required which necessitates a demonstration-scale plant. In addition, the shipping industry is under stress with several major Asian operators in or near bankruptcy which is limiting the source of funding of new initiatives.
Short-haul sea shipping, port ships, and ferries are where most alternative fuels are likely to be used. They are particularly suitable for use in inland waterways and close shore operations because of their lower environmental impact when burned or spilled. Some of these areas are under the complete control of progressive governments who are willing to legislate mandates and subsidies. Also, the ships tend to be smaller so that the lower energy density of the biofuels is less important. The quantities of biofuel required are easier to achieve using smaller first-of-their-kind biofuel plants currently being developed.
There are a number of applications involving smaller vessels already in progress. In Sweden, Stena Line is converting some ferries to run on locally produced bio-methanol. GoodFuels Marine NRG has established a joint venture with ship manufacturers Boskalis and Wärtsilä to develop sustainable “drop-in” marine fuels like UPM’s wood-derived product.
The use of biofuels in larger vessels will be more challenging. The Maersk Group has a corporate goal to reduce CO2 emissions by 60% from 2007 levels. They are playing a key role in testing biofuels and other alternatives in larger ships and have a dedicated container ship for the purpose of testing biofuels provided from a wide variety of sources. They have been involved in testing many different materials over the last several years.
The first use of biofuels will likely be as blends with other more available and less costly fuels. The increasing adoption of liquefied natural gas, methane, and maritime diesel provides easier blending opportunities for biofuel.
Given the current price of biofuels relative to fossil fuels, it is likely that mandates or subsidies will be required to support their initial use. However, it is possible that as the biomass-based economy grows there will be by-products that will be suitable as low-cost blend components. Several analysts agree that biofuels have the potential to replace 10-30% of the current fossil fuels currently used.
The international response to the maritime emissions reduction has been modest at best. The recent COP21 climate change summit in Paris did not address them. The shipping industry as a whole has been slow to react. The Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) failed to issue a greenhouse production target in their spring 2016 meeting. It is difficult to get an agreement that is verifiable and enforceable in view of international maritime law in which no single country has jurisdiction in open oceans.
There is continued pressure from a variety of industrial and environmental sources for governments to legislate targets and regulations that level the playing field between companies dedicated to the sustainable operation and others. Organizations of industrial players like the Sustainable Shipping Institute have been lobbying for new standards. Their members include major ship operators like Maersk and Bunge, shipbuilders, and others. The situation has been highly studied by European, Asian, and US energy and environmental agencies. The US Department of Transportation conducts the Maritime Alternative Fuel Initiative (MARAD) and the US Navy Future Fleet Programs. In June 2016, the European Commission went further calling for a new system for the reporting and the verification of emissions from all vessels using their ports as the first step towards regulation. However, their recommendations have not been adopted.
The International Convention for the Prevention of Pollution from Ships (MARPOL) set regulations controlling sulfur, NOx, and particulate emissions in 2004 which came into full force this year. Until recently, the most commonly used fuel was heavy fuel oil (HFO) with high sulfur content referred to as bunker fuel in reference to the large storage facilities used to inventory the feed. The cost of these feeds has been low since there are few land-based outlets for them without the added expense of sulfur removal. This has been forcing the use of more expensive desulfurized fuels like marine gas oil (MGO) or liquefied natural gas (LNG). However, it is projected that scrubbing technology will be employed that will allow the use of higher sulfur fuels. These scrubbers add additional costs and operating complexities that opened the door to the use of alternative fuels.
The situation for the cruise ship industry transcends these regulatory issues. Cruises ships are not essential for world commerce and are subject to consumer perception. There is a significant movement to convince the public that the environmental price of cruises is too high to be sustainable. They need to demonstrate that they are responding to the problem and taking significant steps to reduce their environmental impact. They may be more amenable to using higher cost, lower impact fuels. Cruise ships tend to travel short distances between ports which reduces the problems with lower energy density.
Recent announcements indicate that cruise lines are moving towards adopting LNG technology. Carnival Corporation is planning on building three new LNG-powered cruise ships with Meyer Werft and Meyer Turk. Royal Caribbean has also announced that two new ships will be powered by liquefied natural gas (LNG) and will introduce fuel-cell technology.
Approaches To Reducing Maritime Greenhouse Gas Emission
There are many opportunities to address maritime CO2 emissions with improvements in ship design and construction. The efficiency of the currently used reciprocating engine technology can be substantially improved with better logistics and technologies such as friction-resistant coatings and lubrication, advanced fuel system automation, and even simply reducing ship speeds. Hydrodynamic improvements to the propeller systems are possible. A recent study suggests that reductions between 50-75% are possible using these approaches. These opportunities for major non-feed-related improvements will compete for development funds and divert attention from the adoption of biofuels that have a smaller impact.
Other propulsion systems are available with potentially improved efficiency. Hybrid propulsion systems that combine mechanical and electrical energy are becoming available for larger ships. New engine technology involving fuel cells has been tested in smaller craft. Nuclear power could be used if safety and regulatory control issues were addressed.
There is the potential to use the size of ships to their advantage. They could potentially carry wind, solar power, fuel cells, and electrical storage equipment. Larger ships have the storage capacity for alternative fuels such as liquefied natural gas, hydrogen, and ammonia, which are typically less energy dense and take up more space than fossil fuels. However, energy density is still a critical consideration in fuel selection since the space required on long-haul ships subtracts from the cargo-carrying capability of the ship.
Currently, auxiliary power for all of the ship’s systems is derived from the main power plant. This parasitic power generation lowers the efficiency of the drive system. Several approaches are being used to address this issue. Methanol-fueled solid oxide fuel cells have been installed on ships to produce auxiliary power. GE has announced a new technology comprised of a shaft generator motor installed between the main engine and the propeller. It acts as either a generator or a booster to generate electricity from slow streaming speeds all the way up to the design speed of the vessel. The first system is being installed on a Maersk Line container vessel.
A Catalog Of Alternative Marine Fuels
There has been a significant effort to identify future fuels for the maritime industry. Many alternative fuels have been tested on actual operating ships including liquefied natural gas, methanol, Bio-diesel, glycerin, algae, and wood-based fuels. Some of these fuels are not drop-in replacements for current ships and will be modifications to existing ships or construction of ships with new fuel and power systems. Others will only be available in selected ports. This limitation can be addressed by constructing flexible power systems capable of operation with one of several fuel sources for the ships not clearly dedicated to a single type of cargo and/or route. The volumes required for shipping are challenging for biomass conversion technologies and currently, none of the possible alternatives are available in the quantities required. It is likely that the fuels will be introduced into the fuel supply pool as blendstocks.
Liquefied Natural Gas
Liquefied natural gas is becoming a common maritime fuel. LNG can be derived from renewable biogas and it should be relatively simple to get blends of fossil and renewable gases tested and approved.
LNG has advantages in efficiency and produces fewer emissions than maritime diesel fuels. It meets sulfur regulations without the need for after-treatment technology. The CO2 emissions are slightly lower than that of diesel. In 2015 there were 63 LNG fueled vessels operating globally with another 76 ships being built that would use the new fuel. However, LNG is a long way from being a dominant fuel choice. Maersk alone has just under 600 ships operating, many of which will continue to use marine diesel for the foreseeable future. Adoption of LNG is limited by the lack of availability of LNG fueling infrastructure at many ports. However, ships are being converted to operate on liquid hydrocarbon or LNG depending on price and what is available in their ports of call.
There are factors limiting the adoption of LNG. Natural gas-powered vessels cost 30% more to build than diesel vessels. Methane can slip past the combustion zone leading to increases in their greenhouse gas emissions. There are pending issues with finding locations that protect the crew quarters from the fuel storage areas. Pressure build-ups in fuel lines are a concern. The lower power density of LNG increases the required size of the fuel tanks on the ships and in the ports. The infrastructure required by the ports is expensive. Safety concerns make getting permits difficult.
Methanol is a liquid at room temperature and as such avoids some of the logistical and safety concerns with LNG use. It also can be produced from renewable sources. However, like LNG, a new port infrastructure will be needed. Major changes in the propulsion systems are needed to address corrosion. Methanol can be prepared from biomass sources, and there are a number of proposed projects aimed at producing renewable methanol.
Interest in using methanol as a maritime fuel has been growing as the production of methanol as a method of converting natural gas to chemicals increases. Many large methanol projects are coming on-stream that plan on shipping methanol globally in large quantities. Port infrastructure is being added to store and handle this material as a cargo. It is logical to use the same material carried as cargo for generating power. Three methanol-propelled tankers were delivered in April 2016 from South Korean and Japanese shipyards. Another four methanol-burning ships are scheduled to enter service in October 2016. There are plans for the construction of many more ships.
Drop-in biodiesel fuels that blend with maritime diesel and heavy oil fuels are very attractive since no changes in existing propulsion systems and infrastructure are needed. They are essentially free of sulfur and aromatics. The main limits on their use are cost and availability.
There are several different materials that are commonly thought of as biodiesel. Fatty acid methyl esters FAME are traditionally called biodiesels. They have significant advantages in the small boat and recreational applications because they are non-toxic and biodegradable.
Renewable diesel is produced by hydroprocessing natural oils. Eni provided biodiesel prepared using their EcofiningTM process for an Italian navy’s offshore patrol vessel Foscari. Another process, catalytic hydrothermolysis conversion (CHCD), was used to prepare diesel by isomerization of hydrothermal extracted plant oils. This fuel was successfully tested by the US Navy.
Lloyd’s Register was involved in a two-year program to test the suitability of biodiesel for use in powering marine engines. The feasibility test took place onboard the Maersk Line container ship, Maersk Kalmar. The results of the test were positive, however, the high costs and low availability led to the conclusion that for the near term biodiesel was not an economic alternative to other approaches to lowering emissions.
GLEAMS Glycerin Fuel For Engines And Marine Sustainability
Glycerin is a by-product of FAME biodiesel production which is generated at levels exceeding market demand in scenarios that maximize FAME use. Several groups have been working on demonstrating its use in marine applications. Marine South East recently completed its project, Glycerin Fuel for Marine Sustainability (GLEAMS), and reported that glycerin “is a technically feasible, very low emissions alternative fuel in the marine market.” Glycerin/diesel emulsions are being investigated for use in smaller crafts by a Maine startup company, Sea Change Group LLC (SCG). Their initial work showed a 3-8% operating cost savings over marine diesel or heavy fuel-water emulsions. However, at current production levels, there is insufficient amounts of glycerin available to be more than a niche player in the maritime fuel market.
The use of wood-based fuels has long attracted attention given the availability of waste products from normal processing. Lignin comprises close to 50 wt% of the wood and has a low value In the current market. Lignin has a high aromatic content and the products from lignin pyrolysis have a high density after they are deoxygenated. As with other biofuels, the cost and availability of testable quantities of material are major hurdles.
In 2013 Maersk announced financial support of two projects aimed at developing lignin-based fuels. To date, there have been no reports of progress. In 2015 the Port of Frederikshavn and Steeper energy, along with Aalborg University have entered into a partnership to establish the world’s first biomass-based plant to produce a sustainable marine fuel from wood.
Goodfuels Marine and Boskail recently reported the successful demonstration of UPM’s wood-based fuel for use in an operating ship. The feed is derived from Toll oil which is a minor component of the wood. It is similar to hydro processed vegetable oil-derived renewable diesel. It does not use the more abundant Lignin.
Algae Derived Feed
Algae continue to attract attention as a fuel source because it can grow at very high rates compared to farmland crops. A number of different methods can be used to convert the collected biomass to a drop in diesel fuel. However, current costs are prohibitive for general commercial use other than experimentally or for performance-based demonstrations. Commercial availability is limited. However, the US Department of Energy and other companies continue to attempt to develop commercial-scale facilities.
Testing by the US Navy showed no adverse effects from using a 50/50 blend of Solazyme algal biofuel with marine diesel. Algae-derived fuel contains almost no sulfur so the SOx exhaust emissions are practically zero.
Fermentation Derived Feeds
The success of subsidized commercial sugar to chemical conversion technology has led to the growth of an industry based on fermentation and biological synthesis. The same fuels being used for land and air applications can be used in maritime engines. The Navy tested Synthetic Iso-Paraffin (SIP) Direct-sugar-to-Hydrocarbon (DSHC) fuels made by converting sugars to a pure paraffin molecule. Bio-butanol and butanol diesel blends have been tested in smaller marine crafts. Recently a 12 1/2 % butanol fuel blend was granted regulatory approval and is being marketed by Gulf Marine Fuels for recreational and small craft at a cost of about $5 gallon or $1500 per ton. While these feeds are technical is capable of powering the engines, their costs and low availability make their use in the near future problematic.
Biofuels can eventually play an important role in lowering greenhouse emissions from maritime sources. A wide variety of materials have been shown to work in real-world applications. However, in the near term, their cost and low availability will likely limit them to niche applications involving smaller craft operating in environmentally sensitive areas. Major reductions in maritime emissions will come from changes in ship design and smart and more efficient powertrains. The shift to new fuels like LNG and methanol will open more opportunities for blending biomass-derived chemicals in the future. Currently, there are no economic or regulatory drivers for the large-scale adoption of biofuels for maritime applications. Since fuels for air and ground transport command higher prices, maritime use of biofuels will likely trail adoption to these more attractive markets.
This article was written in 2016 by Lorenz Bauer (deceased), a former expert with Lee Enterprises Consulting. The views expressed are those of the author and do not necessarily reflect those of Lee Enterprises Consulting. With over 150 experts worldwide, Lee Enterprises Consulting has experts in many specific clean and renewable areas, including anaerobic digestion, fermentation, biomass, conversion technologies for things like tires and railroad ties, organic synthesis, fuel additives, ethanol gas, biodiesel fuel including algae biofuels, solid-state and industrial fermentation, green energy grants, ag-biotech, agricultural waste, alcohol fuels, alternative proteins and animal-free products, sustainable foods, beverage fermentation, biocatalysis, biodiesel conversion, biogas production, biomass power, carbon intensity, co2 utilization, combined heat & power, Fischer-Tropsch technology, food waste, hydrothermal carbonization, industrial enzymes, landfill management, microbial fermentation, organic synthesis, plastic pyrolysis, plastic recycling, plastic waste, pyrolysis oil, reactor design, renewable identification number, the Renewable Fuel Standard (rfs2), solid recovered fuels, torrefaction and torrefied biomass, waste to energy, and waste-to-hydrogen. This is a multidisciplinary group of green energy consultants that is a virtual “one-stop shop” for any client need and handles projects of all types and sizes.
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