A researcher from Ecole Polytechnique Federale de Lausanne (EPFL) claims to have developed a system based on fuel cells to reduce the carbon footprint and energy consumption of cruise ships.
‘It’s easier to reduce the energy consumption of a merchant ship, because almost all of the energy is used for propulsion, unlike a cruise ship, which has various energy demands,’ says Francesco Baldi, a researcher in EPFL’s Industrial Process and Energy Systems Engineering Group (IPESE). ‘My work focused on reducing CO2 emissions, initially by optimising each of the ship’s systems and the design of the boat itself, to improve efficiency.’
According to Baldi, these first efforts produced a potential 6–10% reduction in CO2 emissions for a diesel-powered cruise ship.
However, the researcher sought to increase this reduction by way of alternatives to diesel engines. In a collaborative project with Aalto University in Finland, which received funding from the European Union’s Horizon 2020 research and innovation program, Baldi looked at using fuel cells on a ship. This required addressing the challenges that arise when sailing for thousands of kilometres at a time.
‘You need to store enough energy on board without taking up too much space,’ says Baldi. ‘Hydrogen fuel cells are not suitable, because storing enough energy to travel long distances would take up a huge amount of space – around one third of the ship’s capacity – which is not realistic for a cruise ship.’
According to Baldi, although they require high temperatures to work and take up to 20 hours to turn on, solid oxide fuel cells (SOFC) are said to be a good fit for ships. Therefore, a use for the surplus energy which results from having them in constant use (which is necessary given the long start-up times), needed to be found.
Baldi sought to use a system developed at EPFL to transform unused energy into hydrogen, which is then stored. The resulting fuel cells, customised for ships, could thus generate either electricity to be consumed on board or hydrogen to be stored for later use. According to Baldi, this concept is particularly well suited to cruise ships.
It was noted that one of the advantages of fuel cells is that they only produce CO2 and water, unlike a diesel engine which also produces other pollutants, such as nitrogen oxides and particulate matter. Fuel cell generate power though a chemical reaction. This is said to make them much more environmentally friendly than fossil fuels – and also more efficient: the fuel cells developed at EPFL have achieved 75% efficiency versus less than 50% for even the most efficient diesel engine.
However, despite the environmental benefits, fuel cells cost 10 times as much to produce as a traditional engine.
‘But prices will fall if demand increases,’ argues Baldi. ‘Also, the long-term cost is only 20–30% higher than that of a traditional engine and opting for this cleaner type of fuel will enhance the image of the ships’ operators.’….
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