Until the COVID-19 pandemic hit the world, the cruise industry was prospering in an international and steadily growing market. In the summer of 2019, about 850 000 cruise tourists visited Norway, spending more than 2 billion NOK as a direct financial accretion to the Norwegian economy. While the cruise industry has been significantly impacted by the pandemic, the International Maritime Organisation (IMO) has circulated guidance on a gradual and safe restart of cruise ship operations in European waters.
CruiZE – Cruising towards Zero Emissions – is a collaborative project between SINTEF, NTNU, the world's largest cruise line operator, Carnival Corporation & plc, and Norwegian suppliers of design solutions and equipment to the cruise ship industry. The goal is to develop energy-efficient technologies towards a more environment-friendly cruise industry. The main focus of the project is to suggest innovative heating and cooling concepts, optimised for the ships' propulsion system and varying operating conditions, that can enable zero emissions in ports, minimised emissions at sea, and an average reduction of the ships' total energy usage by 10-20%.
National and international regulations
Cruise ships use a lot of energy and represent an energy-intensive segment of the shipping industry. In Norway, the annual energy use of cruise ships has been estimated to about 5 TWh, corresponding to 8% of the total energy used for transport.
The energy demand of cruise ships is traditionally supplied by burning fossils fuels, leading to a higher carbon footprint per passenger in addition to air pollution in major ports worldwide. Due to this, the cruise industry is facing ever more stringent regulations to emissions. To decrease the maritime carbon footprint, IMO has adopted a strategy to reduce the total annual greenhouse gas emissions from ships by at least 50% by 2050, compared to 2008. In Norway, the Parliament (Stortinget) has adopted a resolution that the World Heritage fjords – Geirangerfjorden and Nærøyfjorden – shall be free from cruise and ferry emissions no later than 2026.
Current efforts towards 'greener' and more environmentally friendly cruise ships have to a large extent focused on novel hybrid propulsion systems based on liquid natural gas (LNG), batteries and hydrogen. New propulsion systems, however, imply a significant change in the energy system of the ships regarding waste heat characteristics and heating/cooling loads. To fully realise zero-emission cruise ships in a cost- and energy-efficient way, it is crucial to put more efforts into reducing the energy usage of the hotel facility systems on board the ships.
The hotel facilities on board cruise ships
For cruise ships, the energy consumption of the hotel facilities on board the ships may constitute up to 40% of the ship's total energy usage. This makes cruise ships significantly different from other shipping segments where the energy consumption is dominated by the propulsion system. In CruiZE, the focus is to develop innovative and energy-efficient concepts for the hotel operation of cruise ships, including technologies for waste heat/cold recovery, compact thermal storage, heating, ventilation and air conditioning (HVAC), fresh-water production, and provision refrigeration.
