CREDIT card-style plastic “keys” are helping to make Southampton cruise ship Azura, one of the greenest vessels afloat.

P&O Cruises’ Azura is typical of a new breed of eco-conscious cruise ships, operating under the toughest of environmental regulations.

When passengers check in they are issued with a cruise card. These have been used as on-board credit cards on “cashless’’ cruises for years, but Azura has taken the idea to a new level.

Besides acting as a key to a passenger’s cabin and a personal security pass, the card fits into the slot of a small device on the wall of the accommodation to turn the power in that particular stateroom on and off.

As passengers leave or return to their cabin, the card is removed or inserted, so regulating the electricity supply.

Previously a huge amount of electricity was wasted by passengers leaving lights on in their cabins while they were out and about around the ship. The news system makes a major contribution in reducing the amount of power needed by the vessel.

By using less fuel, Azura’s emissions have been cut back, so reducing its carbon footprint.

Azura also has an independent environmental officer on board, providing support and advice to the ship’s company on green issues.

World Wide Cruising Standards are a set of rules that are adopted throughout the fleet of P&O Cruises’ parent company, Carnival UK, which has its corporate headquarters in Southampton.

Azura is fitted with six powerful sewage treatment plants and all waste is processed through these and discharged in accordance with the company’s regulations, which are more stringent than official requirements.

While Azura is berthed at her home port of Southampton used cooking oil is collected and sent ashore for conversion to biodiesel, to be used by the contractor in its barge and vehicle fleet.

During a voyage all cans and glass are crushed in special compacting machines.

Azura also has the ability to burn general waste.