Engines of the future
Theory and practice

Engines of the future

What will the yacht engine of the future be like?


Engine manufacturers are looking for a new solution to help reduce their environmental impact. It is time for the internal combustion engine to give way to more environmentally friendly options. Whether running on liquid propane, hydrogen, electricity or a hybrid - what will be the engine of the future for a yacht?

Text - Alain Brousset

The glaciers began to shrink too quickly, which clearly indicates warming. Next to Al Gore, who reminded us of the gravity of the situation, was French photographer Jan Bertrand. In his film «Man», sponsored by billionaire François Pinault's PPR group, the accusations were made against industry and vehicles that emit exhaust gas into the atmosphere.

In December 1997, representatives of 160 countries met in Kyoto and decided to reduce (by 5-9% depending on the continent) the emission of greenhouse gases, including CO2 or carbon dioxide, which is one of the products of internal combustion engines, both gasoline and diesel.

It's time for engine manufacturers to find a solution. What about private shipping? Private ships have 40 times less impact on the atmosphere than commercial shipping. But that does not mean that our sector is completely free of liability. For about 15 years there has been a European RCD (Recreational Craft Directive), according to which inland combustion engines of private vessels should reduce the environmental impact.

The first stage, i.e. no emission of unburned fuel particles, has already been achieved. The second stage is more complex, as it involves reducing particulate matter in the exhaust gases from combustion: carbon dioxide and nitrogen oxide. Since 1997, designers have been able to reduce emissions by more than 50%. Without a radical change in the diesel engine principle, the specialists worked on numerous other aspects: improvement of the inlet quality, significant pressure increase (from 150 to 1800 bar) due to the use of a common fuel line, new forms of combustion chambers, pistons, turbines, exhaust pipes. Manufacturers of engines designed for private shipping have seriously studied the aspect of environmental damage.

Hybrid engine

This type of engine, already announced in the automotive industry (Toyota Prius, Lexus, BMW 5, 6 and 7 series) as well as in shipping (Mochi Craft Long Range 23M), is the most suitable solution today. It is based on a combination of a traditional diesel and electric motor. They are not connected directly. If they are tied to a single transmission shaft, they can work separately. This means that in some cases you can only go electrically. The advantages are no pollution and no noise. The disadvantages are reduced speed and autonomy.

Batteries are used to store electrical energy and are recharged by diesel generators. This is just the beginning, but it's already promising. Almost all manufacturers of marine engines - MTU, Caterpillar, MAN, Volvo and Cummins - are actively working in this direction.

Electric engine .

Could have been an ideal solution: no pollution and no noise. But today it is successfully used only on boats no longer than 7 meters long and with a maximum speed of 5 knots. Of course, there are high power motors (up to 1,000 kW), but their power supply involves a large number of batteries and generators. It may seem that this «pure» type of thrust cannot be successfully used in private shipping. However, the famous French navigator Gérard d'Aboville recently launched the Planetsolar project, a revolutionary catamaran 30 meters long, equipped only with electric motors powered by batteries and solar panels of 470 square meters. It will only be at the end of 2010, when PlanetSolar completes its circumnavigation, that it will be clear how viable these ideas are from a technical point of view. Arcadia Yachts Italy has provided 85, 115 and 135-foot solar-powered yachts to power its on-board equipment, while the propulsion will be from diesel engines.

Electricity + fuel cells

It should be noted at once that this combination is not the same as a hydrogen engine. Fuel cells are generators of electrochemical energy that convert the chemical energy of combustion into electricity. Hydrogen is their preferred «fuel». Fuel cells feed a traditional electric motor through a DC generator. In addition to hydrogen, the fuel cells also run on methanol. Their efficiency is considered to be high, about 50% more than a conventional battery. The disadvantages of their use are complex storage and supply, not the lowest hydrogen price and manufacturing cost (catalysts contain platinum and graphite). Maximum operating time does not exceed 1000 hours. Austrian shipyard Frauscher has produced a small boat (7 meters), equipped with this power plant, but with mixed draft speed does not exceed 10 knots.

Hydrogen engine

This type of engine has nothing to do with the fuel cell. It's a heat engine that runs on hydrogen, not gasoline. The only exhaust would then be water vapour. For two years now, the BMW Series 7 has been running on both gasoline and hydrogen at the same time and has shown excellent results. Unfortunately, hydrogen requires extreme care during transport and storage. It is a very expensive fuel and there are few storage stations for it. There are high restrictions, some engine elements need to be more durable. Despite this, this technology is predicted to have a great future.

A liquefied gas engine

This technique is not new, it is already successfully used in land transport. Heat engine running on gasoline or diesel is quite easy to accept as fuel natural gas with small transformations. Recently, Mercury has produced outboard gas-fired boat engines. Everyone believed that the new fuel could be a solution to reduce harmful emissions. But the first problem didn't take long. First, oil traders slowed down the spread of this fuel at an affordable price, and the second pitfall was safety. There have been a couple of very unpleasant incidents (the explosion of tanks in two boats), and today gas is not used in private shipping. However, it continues to be used by shipping companies. Rolls-Royce has equipped the 132-meter container ship Sea Cargo with a sophisticated system that includes a gas engine that reduces CO2 emissions by 20% and nitrogen oxide by 90%.

Published in YACHTS magazine #32.

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