A comparison of the results obtained from the 2 degree scenarios with and without a shipping carbon budget (TG2D and TG2D CB) can be useful to analyses the differences between a future fleet with or without the use of hydrogen.
Despite the fact that both scenarios TG2D and TG2D CB simulated a decarboni- sation of the energy system that ensure an average global temperature rise below 2◦C, the shipping emissions and the associated share have different trajectories. Figure 6.11
Figure 6.10: Average carbon factor by ship type (top), EEOI by ship type (bottom)
displays the shipping CO2 emissions and annual shares on the global CO2 for TG2D
Chapter 6. Implication of using hydrogen 166
the contribution of shipping emissions increased reaching 5.2% of the total in 2050. The shipping CO2 emissions increased from approximately 450 million tonnes in the base
year 2010 to approximately 1000 million tonnes. In TG2D CB the contribution of ship- ping emissions increased similar to the one in TG2D until 2025. Afterwards the CO2
emissions started to decrease reaching 2% of the total in 2050.
Figure 6.11: Shipping CO2emissions and annual shares of the total CO2 for TG2D
and TG2D CB scenarios
Figure6.12 shows the shipping operational CO2 emissions by fuel type.
The trajectory of the shipping emissions share in the scenario with a carbon budget in shipping is associated with the decarbonisation of the rest of the energy system. It is possible to link the response of the shipping system with the responses of the other main economic sectors in order to analyse the emission implications of using hydrogen in shipping within the context of a decarbonised energy system.
Under the assumption that the global energy system acts as a single entity to mitigate emissions, carbon credits flow to the sector with the lowest mitigation costs first. So the sectors in which mitigation measures can be applied in the most cost-effectively manner will decarbonise first. Figure6.13on the top shows the annual CO2 emissions by sector.
Figure 6.12: Shipping operational CO2emissions by fuel type in TG2D CB scenario
From 2010 to 2035 the electricity power sector is responsible for the majority of decarbonisation, reducing its share from 31% to 7%. The electricity sector would be affected by a significant change switching to clean technologies such as renewables. The carbon intensity reduction of this sector is seen as the least cost option during the first 25 years of the examined period which should ensure an optimum use of primary energy sources in order to meet the 2C-temperature rise target.
From 2035 to 2050 the CO2 sequestration technologies become of significant impor-
tance. The access to CO2 emissions sequestration technologies and to “clean” electric-
ity contributes to the global decarbonisation. During this period the transport sector (excluding shipping) also decarbonises thanks to the availability of clean electricity, re- ducing its share from 30% to 28%. Sectors such as industry also contributes to the decarbonisation.
Focusing on the transport sector, figure6.13 on the bottom shows the annual CO2
emissions for all transport modes indexed to their value in 2010. With respect to the value in 2010, the shipping emissions trajectory shows a similar trend in comparison with the decarbonisation trajectory of car category. However, truck (HGV, LGV) and
Chapter 6. Implication of using hydrogen 168
Figure 6.13: Emissions by sectors in TG2D CB scenario(top). Annual CO2emissions
bus categories drastically reduce their emissions from 2030/2035. Bus and LGV reduce their emissions to almost zero. All together, they are responsible for the decarbonisation of the transport sector during this period. In comparison with the global decarbonisa- tion trajectory the latter categories start to decarbonise later than other sectors (e.g. electricity).
Aviation and rail emissions increase over the period 2010 to 2050. These sectors are difficult to decarbonise from the point they are in 2010. While rail does not account for a significant share of the emissions emitted by the transport sector, aviation does. It is expected that the two sectors will offset CO2 emissions over the period 2010 to 2050.
Within the transport sector, the car, truck and bus mode categories would start to adopt clean technologies from 2035. As an example, figure 6.14 presents the fuel share mix in car, bus and truck transport modes categories. Car appears to switch gradually to electric based vehicle, while bus switches to fuel cells vehicles with hydrogen. In category bus, for example, hydrogen takes up from 2035 and until 2050 its share reaches almost 100% in this category as shown in figure 6.14. In category truck instead a significant share of hydrogen starts in 2040 and increases to about 50% in 2050, while for the category car hydrogen share is quite low being constant around 3% over the period 2040 to 2050. Hydrogen in large vehicles like the categories truck and bus could be favoured as for those categories battery electric vehicles may be unsuitable.
The decarbonisation of the other sectors made available offsets of CO2. This means
that during the first period 2010 to 2030 shipping would be in competition for CO2
offsetting. The main competitor in the transport sector would be aviation.However, the purchasing of CO2 offsets would not be sufficient to meet the target trajectory meaning
shipping emission share would therefore increase in that period (see figure6.13). Under the assumptions that the purchasing of emissions credits outside of the ship- ping industry is limited to a certain share, some in-sector decarbonisation would be required. Shipping carbon price would have to be higher than the global carbon prices, to make it reasonable to purchase offsets and to enable the uptake of emissions reduction measures. As consequence, the increasing carbon price adjusts the cost-benefit evalua- tion and hydrogen can become economically viable from 2030. Switching to hydrogen would reduce the operational shipping emissions and the associated shipping emissions share during the period 2030 to 2050 (see figure 6.13).
Chapter 6. Implication of using hydrogen 170
Figure 6.14: Hydrogen share by mode in TG2D CB scenario
6.3.3 Hydrogen supply and consumption in the decarbonised energy