Hydrogen has gained much spotlight as alternative energy fuel in recent years. The marine industry is also now seriously considering Hydrogen as a viable option. There are several ongoing studies to study the viability of Hydrogen as a possible fuel. This post will look at Hydrogen and give you some key facts.
Hydrogen is a colorless, odorless, and non-toxic gas. There are three ways in which ships can use hydrogen for marine applications:
- Cryogenic Liquid: The volumetric density of liquefied H2 (LH2) (71 kg/m3) is only 7% that of HFO. This results in approximately five times the volume compared to the same energy stored in the form of HFO, resulting in more volume and transport cost.
- Compressed gas under high pressure: When stored as a compressed gas, its volume is roughly ten to 15 times (depending on the pressure [700 to 300 bar]) the volume of the same amount of energy when stored as HFO.
- Hydrogen can also be stored within solids (a phenomenon called absorption) or on the surfaces of solids (adsorption). Both of these methods are not so commonly utilized in marine applications.
Hydrogen is the lightest of all elements, around 14 times lighter than air. Due to its density, it leaks very quickly and thus requires special attention in handling and logistics.
Despite its difficulties in handling, Hydrogen is a widely used chemical commodity. It can be currently produced in two ways:
- Using Natural Gas: note that CO2 is a byproduct of this extraction process. If carbon capture is part of the process, it can significantly reduce carbon emissions.
- Using electrolysis: this relates the cost to the generation of electricity. Electrolysis is particularly interesting because it does not require any existing infrastructure except electricity generation. In particular, if the electricity is produced through nuclear and renewable energy, then carbon emissions can be extremely low if not net zero.
But what technologies can be utilized to generate energy from Hydrogen without carbon emissions and any compromise on efficiency?
Fuel cells seem to be the most popular method, mainly because it doesn’t produce any carbon and could even eliminate NOx, SOx, and particulate matter (PM) emissions from ships. Other technologies are also being considered, including gas turbines and internal combustion engines. The important thing to note is that the lifetime of fuel cells is shorter than that of piston engines or turbines and depends on fuel quality and system operation management. In addition, while carbon emissions are still lower when compared with traditional fuels such as HFO, NOx is unavoidable when using internal combustion engines.
Conventional energy converters for Hydrogen like Internal Combustion Engines will have similar capital expenditures as LNG fuelled engines. But the real kicker comes when considering the cost of storage of Liquid Hydrogen due to its lower storage temperature and higher insulation quality.
The price for H2 in the current market varies significantly because Hydrogen is still a part of the industrial gases market where individual contracts apply. Although one promising aspect to look forward to is when renewable energy production ramps up, then it can be used to produce Hydrogen, reducing the costs significantly
Hydrogen as an alternative fuel is still a promising option despite its complexity in handling and lack of significant infrastructure.
*The numerical data is taken from DNV, Alternative FuelEncyclopedia.
