Techno-economics of ammonia as an energy carrier. Exporting wind from the North Atlantic Ocean/North Sea to Wales

The reduction of greenhouse gas (GHG) emissions requires the deployment of a large portfolio of alternatives. While the electrification of activities based on renewable sources represents the main option for accomplishing the latter, the use of energy vectors such as hydrogen or ammonia will also play an important role to reduce emissions in activities that are hard to decarbonise. The United Kingdom (UK) has already established several goals for producing hydrogen from offshore wind energy resources. However, the transport of this energy is still not known. Based on this context, this work was aimed at analysing ammonia as an energy carrier that could help the UK to exploit and move these resources by quantifying its techno-economics. The objective of this work was also to analyse the case for only considering hydrogen as the energy carrier. Six scenarios were studied, and the results show that the alternative with the lowest levelised cost of hydrogen (LCOH) was the use of ammonia as the energy carrier from Orkney (Scotland) to the Milford Haven Port (Wales) via maritime transportation and its decomposition back to hydrogen without its purification. The LCOH for this scenario was 9.93 USD per kg of H2, which was 0.93 USD per kg of H2 and 2.53 USD per kg of H2 lower in comparison to directly transporting liquid hydrogen or considering the purification of hydrogen via ammonia, respectively. The construction of a hydrogen pipeline from Orkney (Flotta Oil Terminal) to the Milford Haven Port was the next best alternative (11.23 USD per kg of H2), while transporting hydrogen or ammonia via the Teesside Free Port (England) with maritime carrier and pipeline were the highest cost alternatives. A sensitivity analysis was carried out considering different levels of grid electricity and offshore wind costs highlighting an important impact of the first particularly on hydrogen production costs. As a conclusion, we show that ammonia is a feasible energy carrier that represents a large-scale solution comparable to hydrogen in terms of costs, that has the advantage of a relatively rapid deployment while hydrogen (particularly its transport and storage) reaches a more mature stage of development.