Future Fuel Options

John Kokarakis, VP Engineering, Bureau Veritas presentation during the 2015 GREEN4SEA Forum

The tsunami of emission related regulations and the need for environmental friendliness also dictates the utilization of alternate fuels less polluting than HFO. The star player is LNG but  not the only player though. Future ships will burn a variety of fuels; hydrogen, synthetic fuels and biofuels will be chosen depending on the characteristic of the ship.

Nowadays, we are facing an utterly confusing and conflicting tsunami of fuel regulations. Fuel is the most expensive OPEX item and plays an important role in defining the future of the shipping industry. The drivers for new marine fuels are: regulations, financial considerations and available technology. In the future, there is going to be coexistence of multiple fuels. Be aware that the wrong fuel choice has major impact on commercial performance of the vessel. Pioneer owners may be confronted with unforeseen technical issues costing time and money. However shipping thrives through innovation and technology development. The fact that the charterer pays the fuel removes the motivation from the owners to use alternative fuels. Lack of bunkering facilities and supply chains are barriers for the introduction of new “exotic” fuels. Due to the uncertainty in price and availability of fuels, there is a limit to 10-year time window for predictions.

The selection of fuel is based on four criteria: technical, financials, environmental and others. Potential future fuels will be LNG, LPG, Methanol, Ethanol, biofuels and Di-Methyl Ether (DME), nuclear, hydrogen and ammonia in fuel cells. We surely need to avoid cryogenic temperatures to lower the cost of storage. The ‘Toyota Prius’ of the ocean will contain mainly propulsion gadgets such as diesel-electric configurations, fuel cells, batteries, solar panels or wind turbines, and compact superconducting motors.

Biofuels are not new; they have been explored by the automotive industry. They are sulphur-free, easy to burn but they are costly and sometimes have compatibility problems. Fatty Acid Methyl Esters (FAME) is produced from animal fats and vegetable oils, also easy to burn but it has coal flow problems, it degrades and uses corrosion. Also, it is in direct competition with the food chain because FAME relies on palm oil production responsible for the preservation of natural rain forests. Another problem is that biofuels from vegetable oils would require an area about twice the size the United Kingdom. These account for the first generation biofuels. There are also second generation biofuels produced by biodiesel and bioethanol. DME has excellent combustion characteristics but it corrodes and needs lubricity additives and anti-corrosive sealing materials.

Biodiesel is sulphur-free, safe, high flash point fuel but it has flow problems and causes flitter clogging. Biogas is produced by bio-waste and potentially it might replace LNG. Liquid biogas (LBG) also needs cryogenic tanks and pilot diesel fuels to enhance combustion. Its transportation requires additional cost. Algae fuel used to be another promising fuel due to high-yield of the biomass, however today we only find it in the US navy ships. HDRD is another cost- competitive sulphur-free fuel at its infancy but methanol represents one of the most promising alternatives due to the easy conversion for burning and storage. What we gain in the cost of fuel system, we lose at the cost of production. Also, methanol has a low energy density. It is considered as an excellent fuel and easy to handle but it is toxic, has low viscosity which means we have lot of leakages, has a low flash point and it is corrosive. It is produced in an easy way from one carbon monoxide, carbon dioxide and hydrogen which may be found in many sources.

Fuel cells convert chemical energy into electrical and thermal energy. Fuel cell systems are of modular design. Principles governing fuel cell operation have been known for about 150 years. They can be used for propulsion or auxiliary power and also as power sources for offshore oil platforms, underwater facilities and for refrigerated containers. A fuel cell consists of what we call ‘fuel processor’ and a DC, AC inverter. Practically, a fuel cell is an electrolytic device and its processor has a dual function; first, it enriches the fuel to hydrogen- rich gas and second, it removes impurities. As there is no combustion involved, it has very high efficiency because its efficiency is not limited by the Carnot Cycle. What is critical, is that emissions from the fuel cell itself are negligible, consisting mostly of water. The major factor inhibiting fuel cell usage for commercial marine applications is high cost. Ammonia is another fuel that can be used in fuel cells although it is toxic and poisonous gas. It does has problem but it is three times cheaper than gasoline. Also, it needs diesel to facilitate ignition.

In conclusion, biofuels suffer from stability, corrosion, microbial growth and compete with the food chain. So, they need to become cheaper, they might be used as blends. Methanol is a very promising option. It seems that LNG is not the only fuel option. Alternative options may be hydrogen, biofuels and synthetic fuels.  Nuclear propulsion with pressure water reactors appear today only in naval ships. Although fairly developed, the nuclear propulsion has to gain societal acceptance and pass through risk analysis for pollution and terrorist actions. Between 2020 and 2030, we envision that the use of heavy fuel will be at a peak and then it will start to disappear. Then, LNG may take over, if storage tanks are made to cost less than 500 US dollars/ GJ. After 2070, a variety of fuels; hydrogen, synthetic fuels and biofuels may be chosen depending on the characteristic of the ship.We should not rediscover the mercury every time. We need to cross pollinate the knowledge from chemistry. Metal Organic Frameworks are nano porous chemical compounds with very high specific area; one gram of these compounds has an area of a football stadium! They are promising for the storage of carbon dioxide and methane. So, let’s hope that the next generation will achieve much more applications of the metal organic frameworks.  Our proposal for the cheapest and more environmentally friendly solution is to go back to the Greek triremes!

Above article is an edited version of Jonh Kokarakis presentation during the 2015 GREEN4SEA Forum

You may view his presenation video by clicking here