Shipping Renewable Hydrogen Carriers

Abstract

Hydrogen enables renewable energy storage, and hydrogen carriers can allow easier transportation. This research was initiated to get more insight into transporting renewable hydrogen carriers (RHCs) by ship, which is one of the transportation options. The research was conducted in three steps. First, a system description with a literature study was made to select suitable RHCs, based on the production, and the performance as a hydrogen carrier. Secondly, a basic model for three transportation cases was made. Thirdly, a more detailed model was created to evaluate different transportation options. The four most attractive RHCs to be shipped are the synthetically produced: methanol, liquefied natural gas, liquid hydrogen, and liquid ammonia. In the model, short and long term options are evaluated for the same, mild and strict regulations compared to today. The following statements can be made, based on the results of the second model: • Ammonia is best suited in a scenario with strict regulation compared to today. Ammonia has a noncarbon nature; therefore, it is the most promising option in the long term. • Methanol is best suited for small scale transportation in the short and long term, in which the same regulations are active. The storage of methanol on board of the ship is relatively simple and it has a relatively high hydrogen density. • LSNG is best suited for large scale transportation in which the same regulations are active. LSNG has the highest hydrogen density of the discussed RHCs. The advantage of SNG is that during the reconversion to hydrogen, extra hydrogen will be produced because of the added steam, during steam methane reforming (SMR). • Liquid hydrogen is from a shipping point of view not the most suited for the transport of hydrogen, due to its low volumetric density and complex storage. Shipping liquid hydrogen has the advantage that it reduces extra conversion steps in other parts of the supply chain. Shipping RHCs and using the carriers as a fuel is an option which involves higher cost compared to current fossil fuel options. This relatively high share of fuel expenses using RHCs will make efficient powertrains relatively more attractive because it enables higher fuel cost savings. The most attractive engine configurations are a two-stroke internal combustion engine with a mechanical powertrain and a SOFC with a battery in an electric powertrain. The last option is especially promising for the long term, because of the technologic developments and increasing regulations in shipping. Overall the results indicate that shipping NH3 and using the carrier as a fuel is the most promising option for the transport of RHCs by ship. This research and constructed models can be used as a tool to evaluate different transportation options. However, used values are based on various sources and their corresponding assumptions, which can change significantly in the future.