Many companies use natural gas as an energy source – to run their processes and to heat buildings. This energy application can technically be replaced by hydrogen and hydrogen appears to be on the rise as an interesting alternative to the energy system of the future. In the UK an ambitious plan has been presented in which 3.7 million homes and 40,000 companies and industries are being prepared for the switch from gas to hydrogen. The gas network operators Cadent and Northern Gas Networks and the Norwegian company Equinor have proposed a plan for the construction of a hydrogen production, distribution and storage system that supplies hydrogen to households, companies and industries in Teesside, Newcastle, York, Hull, via the existing gas distribution network. Leeds, Bradford, Halifax, Huddersfield, Wakefield, Manchester and Liverpool.
But how can this alternative fuel contribute to the reduction of sulfur emissions from shipping? In part 3 of the series on alternatives to marine fuels, a consideration of the possibilities follows.
DNV GL predicts that by 2035, 39% of the global marine fuel mix will consist of carbon-free fuels such as hydrogen, ammonia and biofuels. The forecast also means that in 2050 these fuels will have a larger share in the mix than oil, LNG and electric propulsion.
Many of these fuels can simply be used in a conventional engine: burning in cylinders, which causes pistons to move. But it is even more economical and environmentally friendly to provide new ships with a fuel cell in which these substances are converted into electrical energy.
Hydrogen is one of the fuels with high potential: hydrogen has no harmful emissions. In addition, the technology is promising, and the reliability is high, certainly in a fuel cell; A fuel cell provides high efficiency, low fuel consumption and is quiet in use. The fuel cell also has no moving parts, and therefore potentially maintenance-free. That means less maintenance costs.
But there are of course disadvantages associated with the use. Hydrogen must be stored under a high pressure of between 350 and 700 bar under the extremely low temperature of -253 degrees Celsius, even lower than LNG. This creates an explosion hazard and complicates the certification of ships.
Another drawback is that hydrogen has a low density. This gives you only 80 kg of fuel per cubic meter, even in the densest liquid form. This means that a lot of hydrogen is needed to sail. A 65-hour voyage with an inland vessel requires around 37,500 liters of hydrogen and a capacity of 750 kW. In terms of energy, this means that hydrogen has less energy than any fuel.
The question is also how long the life span of a fuel cell is. There are experiences with hydrogen in cars, but a life span of 5000 hours is sufficient for a car; for a ship that’s very 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 sea races has been completely converted for this. The Energy Observer started in May 2017 with a six-year trip around the world. Until 2022, the catamaran will moor 101 times in various places, ranging from large capitals to historic harbors and nature reserves.
The Energy Observer makes its own hydrogen on board. The seawater used for this purpose is cleaned on board. To generate the electricity needed to make hydrogen, the catamaran has around 130 square meters of solar panels on deck, as well as two wind turbines. There is also a pilot on board as an environmentally friendly aid to keep the “fuel consumption” of the two electric motors as low as possible. All this must ensure that the ship can sail energy-neutral without harmful emissions of CO2 or particulate matter.
Initiatives are also underway in Norway. The Norwegian government supports a wide range of hydrogen fuel activities with players ranging from the Norwegian Maritime Authority (NMA), the Directorate for Civil Protection (DSB) and the Norwegian Public Roads Administration (NPRA), DNV GL, shipyards and ship owners. With the support of the government, the NPRA set up 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 from the EU for the realization of two commercially operated zero-emission hydrogen ships, in addition to those in Norway, also a ship in France. In Lyon, France, a hydrogen powered push boat from Compagnie Fluvial de Transport (CFT) will serve as a barge ship on the Rhone.
But here the major problem is also infrastructure – infrastructure is only interesting if there are enough ships that run on hydrogen, but as long as there are too few options for bunkering hydrogen, there is little enthusiasm for developing hydrogen-powered ships.
In Japan this is done differently. Here, the use of hydrogen is part of the country’s vision for a clean energy future. Japan is investing heavily in hydrogen: the government has a roadmap, and the industry is working hard. For this purpose, a construction was started in Port Hastings, Australia, where hydrogen is liquefied. 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 the construction in the port of Hastings. These developments could enable Victoria to become a world leader in the fast-growing hydrogen industry, which is expected to be worth $ 1.8 trillion by 2050.
Dual-fuel engines offer the option of sailing on multiple types of fuel: usually a clean fuel combined with diesel. This makes the deployability of ships with this type of engine large. One of the main arguments for the development of dual fuel engines was that it offers more flexibility than sailing on only one cleaner fuel, for example LNG. If the LNG has been used up, the ship will simply continue to run on diesel.
The dual-fuel technology has eversince 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 for burning 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 of these substances is even less worked out, but the substances certainly have potential.
Hydrogen can serve as a basis for these electro-fuels and, given the low energy density of hydrogen, is probably a more efficient way to use hydrogen. Electro fuels, also known as synthetic fuels, are produced from H2 and CO2 (fuels based on carbon, such as diesel, methane and methanol) or from H2 and nitrogen (fuels based on nitrogen such as ammonia). Renewable electricity is used for production. Carbon – based fuels are drop – in fuels that require only limited adaptation of engines and fuel systems to replace or mix with traditional fuels. Another advantage of carbon-based electro-fuels is that, like conventional fuels, they can have a high energy density. Synthetic fuel requires comparable storage on board as conventional fuel used today.
In part 4, two of these fuels, ammonia and methanol, will be discussed.