Bunker fuel is not known for its green credentials. Viscous, tarry and toxic, it is essentially a waste product – the sludge that remains in the refinery after the lighter oils have been extracted.

When cooled, it is thick enough to walk on. When burned, it emits a slew of contaminants that does not make for a reassuring read.

With carbon dioxide (CO2) being emitted in huge quantities, the shipping industry is believed to be responsible for around 4.5% of emissions worldwide. Of equal concern are nitrogen and sulphur oxides (NOx and SOx), which contribute towards the formation of acid rain.

Most hazardous of all is particulate matter, which, burrowing deep into the lungs, has been estimated to cause as many as 60,000 deaths a year.

To say that bunker fuel poses a challenge for the cruise industry is to understate the case. It only takes comparing bunker fuel to the petroleum used in cars to get the full measure of the situation.

While the sulphur content of automobile fuel in the EU is capped at 15 parts per million, the limit for ships is 3,000 times higher at 4.5%.

"With the cruise industry representing 2% of the overall maritime industry or less, we don’t have a particularly loud voice in encouraging the development of more low-sulphur fuels."

Regulation, regulation

This figure has come under fire from the IMO, whose regulations in the area are in the process of being tightened up.

"Four or five years ago there was a huge surge in the number of new regulations in the pipeline, and they are all now coming to fruition," says James Hunn, vice-president of corporate environmental compliance & maritime affairs at Carnival. "The issue of air emissions is only just starting to boil."

By 2020, the global sulphur emissions cap will be reduced to 0.5%, and as early as 2015 it will be slashed to 0.1% within designated control zones.

Hunn, an ex-navy man who has worked at Carnival since 2002, is confident the corporation can meet these standards. While he concedes it will be tough, he points out "we’re working with the IMO and are complying with their regulations – locally, regionally, and globally. There’s a variety of things that can be done to help meet the sulphur emission requirements as they develop over the years."

The most obvious solution would be to use oils that are naturally low in sulphur. This would undoubtedly be of benefit – when a regulation came into force requiring ships to burn lower sulphur fuel within 200 nautical miles of Canada and the US, the US Environmental Protection Agency estimated the measure would save as many as 14,000 lives a year.

The downside is that lower-sulphur fuels are far more costly. With bunker fuel around 60% cheaper than its cleaner equivalents, it has always been the most economically viable option. A drastic hike in prices would not be what the cruise industry needs to stay afloat.

Another point of contention is availability. "There are questions about whether this very low-sulphur fuel will be available in the required quantities," says Hunn.

"With the cruise industry representing 2% of the overall maritime industry or less, we don’t have a particularly loud voice in encouraging the development of more low-sulphur fuels."

Industry agenda

The real advances look likely to happen where the cruise sector pulls together with the other 98%. Luckily, there is a good deal of consensus across the industry.

"There’s probably closer cooperation on environmental matters than on any other major subject," says Hunn.

"If there’s something bad in the environmental business, whichever part, it reflects badly on all of us. The maritime industry is as one."

"If ships were to move 10% more slowly, it would equate to a 23% reduction in CO2 emissions."

This unanimity was underscored by last year’s inaugural Global Maritime Environmental Congress (GMEC), in which Hunn convened with other maritime representatives to deliberate how they could best "set the green course".

The purpose of this event was to lay out very broadly where the industry was at present and where it should go in future, but subsequent GMEC events will focus on a single area. For example, the 2012 conference will look more closely at air emissions.

With low-sulphur fuels a limited commodity, top of the agenda is sure to be fuel efficiency. Burning less oil is a win-win situation, aligning economic and ecological concerns in that it decreases a company’s environmental footprint and saves money.

In practice, this might entail a range of measures, including travelling at slower speeds. An IPCC report from 2007 demonstrated that if ships were to move 10% more slowly, it would equate to a 23% reduction in CO2 emissions.

Clean options

Other fuel-saving tricks being floated include cold ironing in port. This involves shutting down the ship’s engine when in harbour, and plugging in to a land-based power source.

"That can be a good idea," says Hunn. "We do it at some places in the world now, but it depends on how the power that you’re using is being generated. If the onshore power puts more sulphur into the air than we would have done through our engines, then it isn’t the best solution. You have to look at those on a case-by-case basis."

Ultimately, such measures taken alone are unlikely to yield major results. For emissions to be radically reduced a shake-up in fuel technology is required.

"The problem is the state of this technology isn’t where we would like it to be," says Hunn. "And in that respect I’m talking about scrubbers."

These air pollution control devices are used to extract sulphur from bunker oils. With around half a dozen currently installed on cruise ships, Carnival had the first. They are a particularly resourceful solution, ensuring that the bunker fuel is utilised and avoiding wastage.

"If we can continue to use the heavy fuel oil and treat it to remove the sulphur from the gas, then that’s certainly advantageous to us because of cost factors," says Hunn.

"It’s advantageous to the oil companies as well because if there’s no market for that heavy fuel oil then not only do you lose the ability to sell it, now you have to somehow dispose of it."

Unfortunately, the present uses of scrubbers are limited by their unwieldiness. While factories have been using such technology for years, the scrubbers can often be as large as the factories themselves. On a cruise ship, in which space is of the essence, you simply don’t have the flexibility of carrying one – Hunn compares it to lugging around "half a city block".

Size is the principal obstacle when it comes to many such innovations. Solar power is a good example.

"You can’t have enough solar panels to produce enough power to power a ship, because there just isn’t physically room," says Hunn.

More salient still is fuel cell technology, which Hunn suggests may one day represent the biggest breakthrough in the area.

"Right now you can build stacks of fuel cells that take fuel and convert it chemically, without burning it, and reduce the air emissions," he says. "The problem is they don’t produce enough power per square foot of fuel cell, so they’re very large in footprint."

While fuel cells have minimal market penetration for now, Hunn believes they will become more practicable in the future. The recognised trajectory seems to be that, as a technology is developed, it shrinks from being large and cumbersome to small and super-efficient.

"Electronics is a great example," he points out. "Computers were room-sized a couple of decades ago, and now they’re the size of a thimble. As we continue to downsize our fuel cells and scrubbers I’m confident the same thing will happen."

"For now, the focus will remain on fixing the margins."

This is some way in the future – the likelihood is that new developments in fuel cell technology will come about 30-50 years from now. With the average cruise ship boasting a 30-40-year lifespan, this equates to a whole new generation of ships.

For now, the focus will remain on fixing the margins. Companies such as Carnival are concentrating their efforts on getting more efficient and producing better engines; reducing NOx by 40% and SOx by 30%; saving money and ensuring the IMO regulations are met.

Hunn is clear that the best thing for Carnival will be to initiate a multi-pronged approach: "As any company would do, we’re going to
take the most efficient of those methodologies. I think our optimal solution will be a combination of them."

However, a comprehensive solution to this complex problem cannot come about overnight.
"Most people who have concerns over the environment are thinking about a completely emission-free ship," says Hunn. "But that’s another generation away."