Celebrity Apex and Symphony of the Seas will use the biofuel to “meet part of the ships’ fuel needs”, Royal Group announced, adding the “landmark test” would offer important data and research for its future alternative fuel ambitions.

During the three-month test, Apex will depart from Rotterdam and Symphony of the Seas will sail out of Barcelona using a biofuel blend that reduces the vessels’ carbon emissions.

The biofuel blend is produced by purifying renewable raw materials like oils and fats and combining it with fuel oil to create an alternative fuel that Royal Group claimed would be “cleaner and more sustainable”.

"Biofuels will play an increasingly important role in achieving, not only our own, but the entire maritime sector’s decarbonisation goals in the short and medium term,” said Royal Group president and chief executive Jason Liberty.

“We take great pride in continuing to push our industry forward in exploring innovative fuel solutions that reduce carbon impact and preserve the vibrancy of the oceans we sail.”

Royal Group plans to continue increasing its use of alternative lower carbon fuel, and after its summer trials, plans to increase its usage across other European summer sailings.

This latest announcement follows Royal Group’s biofuel trial with California-based Navigator of the Seas, which became the first cruise ship to sail from a US port while using renewable diesel fuel last autumn.

“With the completion of the trials our hope is to advance our ships’ ability to meaningfully reduce emissions and propel forward strategic partnerships with suppliers and ports to ensure there is sufficient availability of biofuel and infrastructures to make maritime energy transition a reality,” added Liberty.