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Alternative Marine Fuels


Alternative technologies for marine fuels and energy sources have great potential for improving the environmental footprint of waterborne commerce. Innovations are providing new policies, products, and methods to reduce emissions. These innovations include:

• New international and national standards for conventional marine fuels.

• New, innovative fuel concepts.

• New exhaust remediation technology.

• Shore-to-ship alternative powering techniques.

• Ocean-based renewable energy.

Large, slow-speed diesel engines currently predominate in the powering of cargo ships, principally burning heavy fuel oil (HFO). Of all the fuel types used by cargo ships, HFO result in significant levels of certain pollutants, such as SO2 and sulfate particulate matter, due to its relatively high sulfur content. Typical ship exhaust contains the following pollutants, leading to adverse effects on human health and climate change:

• Nitrogen oxide (NOx).

• Sulfur oxide (SOx).

• Carbon monoxide (CO).

• Carbon dioxide (CO2).

• Particulate matter (PM).

• Other greenhouse gases (GHGs).

Ship emissions are being reduced through use of non-conventional fuel to meet new International Maritime Organization (IMO) and U.S. Environmental Protection Agency (EPA) fuel standards. Some of these fuels include liquefied natural gas (LNG), methanol, and biofuels. In addition, other strategies are becoming available to reduce emissions, such as exhaust gas scrubbers and cold ironing (providing electrical power in port).

Biofuels are an interesting option, although fuel availability and uncertainty about long term engine maintenance may affect its application. Exhaust scrubbers, particularly those using salt water, may allow for continued use of high sulfur fuels but could shift an air pollution problem to a water pollution problem and would not help with pending NOx control requirements. Cold ironing or shore power is being considered at a number of ports where infrastructure costs are balanced with benefits. Cold ironing has been implemented at military bases, several California ports (driven largely by a California Air Resources Board regulation that addresses hoteling emissions for ships at berth), Seattle, New York, and in several Canadian ports (Prince Rupert, Vancouver, and Montreal); these systems mitigate dockside port emissions, but do not address emissions while the vessel is underway. LNG-fueled barges can also be used as an alternative power sources for vessels at-berth, at present this technology is primarily used to comply with at-berth fuel regulations in Europe.

Many of these technologies are also applicable for harborcraft, including assist tugs and ferries, who may be operating propulsion and auxiliary engines that are many decades old. Benefits from emission reductions and fuel economy may also be realized from these smaller vessels.

There has been a lot of attention recently on LNG due to current pricing of natural gas and generally low emissions associated with this fuel. Lloyd’s Register estimates that LNG could reach 11% share of marine fuel usage by 2030. The use of natural gas as a transport fuel has been growing steadily over the past decade. This increased activity is evident in many different spheres, including industrial initiatives, public investment in new infrastructure, statements by technology providers, new government policies and incentives, and emerging research projects. Developments in the deployment of LNG-powered vessels and in the construction of new LNG refueling and import infrastructure have been steady since 2006. Three manufacturers—Rolls-Royce, Wärtsilä, and MAN—have developed different LNG engine technologies for marine applications. Spark-ignited, lean-burn engines allow the gas to be mixed with an excess of air before passing through the intake valves, more completely combusting the fuel and reducing efficiency losses. Dual-fuel diesel engines, which can run on LNG or distillates, are gaining traction, but technological improvements are needed to address methane slippage from duel fuel 4 stroke engines.

The infrastructure for LNG is being ramped up to meet the demand for these ships. Norway has already developed a system of small-scale LNG production and storage facilities that supply ferries and other working ships. New LNG shipbuilding contracts around the world are now aligned with some installation of bunkering facilities to provide the fuel. Over the longer term, several governments have bigger plans for LNG in the maritime sector. For example, the European Commission launched an ambitious plan to have 139 LNG refueling facilities for seagoing and inland vessels in the 2020–2025 timeframe. Yet, LNG as a marine fuel is still in the fledgling stages. The following LNG ships are in operation or planned:

• About 30 operating LNG-powered cargo ships (ferries, platform supply vessels, merchant ships, coast patrol, etc.—mostly in Norway), with about 25 on order (including in Canada, Finland, Norway, Sweden, and the United States).

• About 400 operating LNG oceangoing vessels, with an additional 50–100 planned for 2015 through 2018.

• A few large oceangoing vessels in Europe and a handful of container ships in the United States to be delivered between 2015 and 2016.

As a result of these numbers, forecasts are that the growth of LNG-powered ships is unlikely to play a major role in the shipping market in the next decade. Invariably, many barriers to the development of LNG as a shipping fuel will have to be addressed sooner rather than later.

Importantly, the impact of these non-conventional fuels need to be considered along the entire fuel cycle – i.e., from fuel extraction to use. Some fuels that may be environmental ‘winners’ at the ship stack may not be such when emissions from extraction, refining, and delivery are considered.


Life cycle evaluation of alternative marine fuels (low sulfur fuels, biofuels, LNG, electrification) noting appropriate applications as well as technical issue or barriers to use. Results of this analysis can be summarized into a useful format for state and local government agencies, port authorities, and vessel operators that need to stay in front of technological developments to manage fuel costs and comply with current and future air quality rules. This work can also be extended to explore the environmental and human health impacts of these ship emissions.


The goal is to achieve environmental improvements by reducing air emissions, increasing fuel economy using alternative fuels and shore power. To achieve this goal, policymakers and those in industry need to understand the impacts of these fuels on environmental quality

Related Research:

Other studies have evaluated these alternative fuel options separately, but this analysis would allow side by side comparison of the options which would be useful to determine the optimal option of ports and vessel operators.


The following tasks are not comprehensive. They are intended as a guide to what might be necessary to successfully complete the research:

  • Develop, validate, and apply a total fuel cycle analysis for alternative fuels in marine engines; this would be used to populate a database of emissions from alternative fuels along different fuel production pathways for alternative fuels in the marine sector including compilation of propulsion and auxiliary engine emission factors.;

  • Interview alternative fuel providers, port operators, and those in the shipping industry to identify key barriers to alternative fuel implementation;

  • Summarize available alternative fuel technologies, state of commercialization, benefits, costs, and provide examples where the technology has been implemented;

  • Develop optimization modeling approaches to assist in selecting optimal fuel, technology, and operational strategies for reducing emissions in the shipping fleet; apply results of emissions analyses to assess public health and other environmental impacts associated with emissions from ships.

  • Prepare outreach material and PowerPoint presentation for dissemination to potential users/ stakeholders


Study would provide an overview of existing technologies and challenges to using alternative fuels, bunkering at ports in the United States, including storage, fuel availability, fuel transportation, and vessel-side demand. Using lessons learned from ports currently operating alternative fuel bunkering terminals, results of this research might provide a roadmap towards wider adoption of alternative marine fuels.


Very relevant, particularly in light of IMO regulations, ECAs, and other efforts to reduce emissions from ships; particularly regarding LNG as it is often discussed as a cleaner alternative to heavy fuel oil and distillates, research is needed to better understand the relationship between NOx reductions and methane slip. Also a better appreciation of the barriers to adoption may be useful in facilitating options for this discussion.

Sponsoring Committee:AW030, Marine Environment
Research Period:24 - 36 months
Research Priority:Medium
RNS Developer:Richard Billings, Christina Wolf, James Winebrake, Timothy Sturtz, and Ed Carr
Source Info:EPA, EIA, ports, and industry
Date Posted:12/13/2017
Date Modified:01/05/2018
Index Terms:Alternate fuels, Ships, Liquefied natural gas,
Cosponsoring Committees: 
Marine Transportation

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