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Is hydrogen the alternative to gas? Part 3 of alternatives for marine fuels

October 15, 2019

Many companies use natural gas as an energy source - to run their processes and to heat their buildings. This energy application can technically be replaced by hydrogen and hydrogen seems to be emerging as an interesting alternative for the energy system of the future. In the UK an ambitious plan has been presented to prepare 3.7 million homes and 40,000 businesses and industries for the switch from gas to hydrogen. Gas network operators Cadent and Northern Gas Networks and Norway's Equinor have proposed a plan to build a hydrogen production, distribution and storage system, delivering hydrogen through the existing gas distribution network to households, businesses and industries in Teesside, Newcastle, York, Hull, Leeds, Bradford, Halifax, Huddersfield, Wakefield, Manchester and Liverpool.

But how can this alternative fuel contribute to reducing sulphur emissions from shipping? Part 3 of the series on alternatives to marine fuels will look at the possibilities.

Hydrogen

DNV GL predicts that by 2035, 39% of the global marine fuel mix will be carbon-free fuels, such as hydrogen, ammonia and biofuels. The prediction also implies that by 2050, these fuels will have a greater share of the mix than oil, LNG and electric propulsion.

Many such fuels can be used in a conventional engine: burned in cylinders that set pistons in motion. But it is even more economical and environmentally friendly to equip new ships with a fuel cell that converts these substances into electrical energy.

Hydrogen is one of the fuels with great potential: hydrogen has no harmful emissions. In addition, the technology is promising and the reliability is high, especially in a fuel cell; a fuel cell gives high efficiency, low fuel consumption and is quiet in use. The fuel cell also has no moving parts, and is therefore potentially maintenance-free. This means lower maintenance costs.

But there are of course disadvantages associated with its use. Hydrogen has to be stored at a high pressure of between 350 and 700 bar at the extremely low temperature of -253 degrees Celsius, even lower than LNG. That creates a risk of explosion and makes the certification of ships complicated.

Another disadvantage is that hydrogen has a low density. As a result, you only get 80 kg of fuel per cubic meter, even in its densest liquid form. This means you need a lot of hydrogen to sail. For a 65 hour journey on an inland waterway vessel, around 37,500 litres of hydrogen and 750 kW of power are needed. In terms of energy, this means that hydrogen has less energy than any fuel.

There is also the question of how long the life span of a fuel cell is. There are experiences with hydrogen in cars, but for a car a life span of 5,000 hours is sufficient; for a ship that is quite different with 250,000 hours.

One of the ships that is already completely powered by hydrogen is the Energy Observer. This catamaran that once sailed veryaces has been completely converted for this purpose. In May 2017, the Energy Observer embarked on a six-year voyage around the world. Until 2022, the catamaran will make 101 stops at various locations, ranging from major capital cities to historic ports and nature reserves.

The Energy Observer produces its own hydrogen on board. To do this, it uses seawater that is cleaned on board. In order to generate the electricity needed to make the hydrogen, the catamaran has some 130 square metres of solar panels on deck, as well as two wind turbines. There is also a kite on board as an environmentally friendly aid to keep the 'fuel consumption' of the two electric motors as low as possible. All this should ensure that the ship can sail energy neutrally without harmful emissions of CO2 or particulates.

Initiatives are already underway in Norway as well. The Norwegian government supports a wide range of hydrogen fuel activities with players ranging from the Norwegian Maritime Authority (NMA), the Directorate of Civil Protection (DSB) and the Norwegian Public Roads Administration (NPRA), DNV GL, shipyards and shipowners. With the support of the government, NPRA initiated a project in 2017 with the ultimate goal of building and operating a hydrogen-electric ferry on the Hjelmeland-Nesvik route on the southwest coast. This project has now received financial support from the European innovation project FLAGSHIPS.

 

FLAGSHIPS has received 5 million euro from the EU for the realisation of two commercially operated zero-emission hydrogen-powered vessels, in addition to the one in Norway and one in France. In Lyon, France, a hydrogen-powered pusher tug from Compagnie Fluvial de Transport (CFT) will serve as an inland waterway vessel on the Rhône.

But again, the big problem is infrastructure - infrastructure is only interesting if there are enough hydrogen-powered ships, but as long as there are too few opportunities to bunker hydrogen, there is little incentive to develop hydrogen-powered ships.

In Japan, the approach is different. Here the use of hydrogen is part of the country's vision of a clean energy future. Japan is investing heavily in hydrogen: the government has a roadmap, and the industry is working hard on it. To this end, the construction of a hydrogen liquefaction facility has started in Port Hastings, Australia. The project will be delivered by a consortium of Japanese energy and infrastructure companies led by Kawasaki Heavy Industries (KHI) and including J-Power, Iwatani Corporation, Marubeni Corporation and AGL, with KHI and Iwatani leading construction at Port Hastings. These developments could make Victoria a world leader in the fast-growing hydrogen industry, which is expected to be worth $1.8 trillion by 2050.

Is hydrogen the alternative to gas? Part 3 of the series on alternatives to marine fuels
Foto DNV-GL

 

Dual fuel

Dual-fuel engines offer the possibility to sail on several types of fuel: usually a clean fuel combined with diesel. This makes ships with these types of engines highly deployable. One of the main arguments for the development of dual fuel engines was that it offers more flexibility than sailing on just one cleaner fuel, for example LNG. When the LNG runs out, the ship just keeps on running on diesel.

The dual-fuel technology has proven itself. The advantage of dual-fuel engines is that they are generally flexible enough to adapt easily to more environmentally friendly fuels. The engines can also be converted to burn methanol and NH3 (from fossil or renewable sources) and fuels mixed with hydrogen.

 

Hydrogen is the best known non-fossil energy carrier for shipping, but not the only one. There are several possibilities - in general, the technical feasibility for these substances is still less developed, but they certainly have potential.

Hydrogen can serve as a basis for these electrofuels and, given the low energy density of hydrogen, probably a more efficient way to use hydrogen. Electrofuels, also called synthetic fuels, are produced from H2 and CO2 (carbon-based fuels like diesel, methane and methanol) or from H2 and nitrogen (nitrogen-based fuels like ammonia). In these cases, renewable electricity is used for production. Carbon-based fuels are drop-in fuels that require only limited modification of engines and fuel systems to replace or blend with traditional fuels. Another advantage of carbon-based electrical fuels is that, like conventional fuels, they can have a high energy density. Synthetic fuels require similar on-board storage as conventional fuels used today.

Part 4 will look at two of these fuels, ammonia and methanol.