Page 27: of Maritime Reporter Magazine (May 2021)

GREEN CLASSIFICATION the shipping industry to succeed with cutting greenhouse gas ergy for hydrogen production increase. Hydrogen Hubs using a emissions, energy ef? cient measures alone are not enough. combination of wind, solar and wave energy to lower the cost of

Low-emitting alternative fuels in the decarbonizing journey production in the medium term are could be commercially vi- are critical to the industry’s transition to a low carbon future. able with proven technology. Reducing the cost of green hydro-

One possible ‘near-term’ solution is hydrogen – a zero-car- gen to $2/kg can make it competitive for use in the marine sector. bon fuel that is being considered for use in marine applica- The heating value of hydrogen is the highest among all can- tions. The other zero-carbon fuel is ammonia and the produc- didate marine fuels at 120 MJ/kg. However, its energy density tion pathway of the two are very much interlinked. Hydrogen per unit of volume, even when lique? ed, is signi? cantly lower can be produced from many different sources, utilizing con- than that of distillates. Compressed hydrogen at 700 bar has ventional or renewable energy, which determine the cost of the only ~15% the energy density of diesel, and therefore in stor- fuel to the end user, as well as its lifecycle carbon footprint. ing the same amount of energy onboard requires about 7 times

Its extraction can be manufactured from fossil fuels and bio- larger tanks. This means that compressed or lique? ed storage mass, or from water, or from a combination of the two. In of pure hydrogen may be practical only for small ships that terms of energy usage, the present-day energy used globally have frequent access to bunkering stations. The deep-sea ? eet for the production of hydrogen is about 275 Mtoe. This relates may need a different medium as a hydrogen carrier, such as to 2% of the world energy demand [IEA, 2019]. Natural gas ammonia or Liquid Organic Hydrogen Carriers (LOHC), to is the primary source of hydrogen production (gray hydrogen, limit signi? cant loss of cargo space. Ammonia has higher en- 75%) and is used widely in the ammonia and methanol in- ergy density than hydrogen which reduces the need for larger dustries. The second source of hydrogen production is coal tanks, but its advantages need to be weighted against the en- (brown hydrogen, 23%), which is dominant in China. The re- ergy losses and additional equipment required for conversion maining 2% of global hydrogen production is based on oil and to hydrogen before it is used in the engines or fuel cells [IEA, electric power. However, the most interesting future option 2019]. Alternatively, ammonia can be used directly as a liq- is the production of green hydrogen through electrolysis of uid fuel in engines, rather than in use as a hydrogen carrier. water using fully renewable energy. Reducing the size of the tanks needed for hydrogen storage is

Strong dependence on natural gas and coal means that the an active research area. In addition, hydrogen storage in solid- production of hydrogen is very carbon intensive, ranging be- state materials such as metal and chemical hydrides, is in the tween 10 tCO2/tH2 for natural gas to 19 tCO2/tH2 for coal, very early stages of development but it can enable higher den- but these emissions can be reduced with the use of carbon cap- sity of hydrogen to be stored at atmospheric pressure.

ture and sequestration technology. The extraction of hydrogen Then we come to the actual bunkering facilities where costs from natural gas is achieved through reformation using three are expected to be higher than that of LNG facilities, primarily methods: (i) steam reforming, which uses water as an oxidant because of the higher cryogenic storage requirement of liq- and a source of hydrogen, (ii) partial oxidation, which uses uid hydrogen and the material required for tanks, pipes, and the oxygen in air in the presence of a catalyst, and (iii) auto- seals. The key component costs are the storage and bunker thermal reforming, which is a combination of the ? rst two. vessels, which need to be scaled based on the number of ships

In all cases, syngas (CO + H2) is formed and then converted serviced. In smaller ports the on-site availability of hydrogen to hydrogen and CO2 through the water-gas shift reaction. would be needed given the lower ? ows and high cost of dedi-

However, in order to reduce the carbon intensity of hydro- cated hydrogen pipelines. However, ship and infrastructure gen production, biomass can be used for production of syngas costs are a relatively small fraction of total shipping costs over though gasi? cation, or renewable electric power can be used a typical 15-20 year lifespan, with the fuel cost being the pri- to electrolyze water. Once produced, hydrogen can be stored mary factor [IEA, 2019].

as a gas or liquid, depending on the amount, the storage time, Developing the hydrogen economy is seen in energy and and the required discharge rate. Storage is a further area of transport sectors as the potential long-term objective to provide consideration. Different applications create different storage a sustainable and clean future. Ship owners, ports and regulato- needs as hydrogen use can range from small-scale mobile and ry institutions like the IMO, will have to make strategic choices stationary applications, to large-scale intercontinental trade. on the methods of hydrogen storage for shipping. The transi-

The availability and low cost of coal and natural gas make tion to hydrogen requires its production from clean renewable the production of hydrogen more economical in the near-term. sources and the commercialization of fuel cells. Fuel supplied

The cost of brown and gray hydrogen ranges between $1-4/kg, directly from hydrogen sources, rather than through the reform- whereas that of green hydrogen currently ranges between $6-8/ ing of other hydrogen carriers, is the preferred option. It is an kg. The cost of producing green hydrogen since 2015 has fallen important part of our clean and secure energy future, and a sig- by about 50%, and this trend is expected to continue up to 2030 ni? cant contributor to the reduction of energy consumption and and beyond, as the projects focused on deploying renewable en- greenhouse gas emissions in the maritime sector.

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MR #5 (18-33).indd 27 5/6/2021 5:26:48 PM