DNV GL expects that liquefied natural gas (LNG) will be the most effective fuel for shipping to reduce its carbon emissions in the medium term, with little prospect of being able to use zero-emission (at the point of use) fuels such as hydrogen for deepsea shipping for a number of decades.
According to the 2019 Energy Transition Outlook (ETO), the world is not currently on course to meet the requirements of the Paris COP 21 climate agreement, with a temperature increase of 2.5⁰C the most likely outcome in 2050, barring, in the words of DNV GL CEO Remi Eriksen, an unprecedented shift to renewables or “magical” solutions “such as nuclear fusion”. The biggest step towards meeting the agreement would be the electrification of land transportation infrastructure, Eriksen said. “Existing technology can help us meet with the Paris agreement, but only with strong global policy backing.”
For shipping’s part, 80% of emissions are produced by the deepsea segments, which have little hope of using batteries to supply the energy they need. Meanwhile, hydrogen is being written off as impractical for these segments.
According to DNV GL, there are three possible pathways for the future fuel landscape. The first is a business-as-usual approach that does not meet International Maritime Organization (IMO) targets but still produces carbon dioxide (CO2) reductions of about 27% by 2050. “That is only about half of what is required to meet with the IMO goals,” said Knut Ørbeck-Nilssen, CEO, DNV GL – Maritime.
The second scenario is ‘gradually stricter operating requirements’, which “would lead to LNG dominating the fuel mix, with liquid biogas [more sustainable LNG] or electrofuels [synthetic LNG, synthetic methane] becoming more popular from 2040”, Ørbeck-Nilssen said, “and would be one of the ways of meeting the targets”.
The next option, the strictest requirements, would result in newbuilds switching to ammonia, a less technically challenging liquid storage medium for hydrogen. “This would result in a slower transition, but if new requirements come in in 2040, zero-carbon fuels could take over. In this scenario, ammonia could be the winning carbon-neutral fuel.”
From an environmental point of view, an unprecedented shift in feedstocks, far faster than what is being achieved in the rest of global power generation, would be required if hydrogen – in the form of ammonia or otherwise – is to benefit the environment. If hydrogen does replace LNG as the future fuel of shipping, its production must move away from the more-than-90% hydrocarbon feedstock-base of today. If not, according to DNV GL’s calculations, the implications for the climate could be worse than doing nothing.
“Our modelling shows that ammonia, biodiesel, liquid biogas, and electrofuels are some of the most promising carbon-neutral options for deepsea ships. Electricity, hydrogen, and ammonia are all carbon neutral, if produced from non-fossil energy or fossil energy with carbon capture,” said Ørbeck-Nilssen.
Notably, these future fuel cases have safety implications above and beyond what is seen today. LNG or liquid biogas, if it leaks from a ship’s tanks, would freeze metal it comes into contact with, rendering it brittle and potentially compromising a ship’s structural integrity. This would ultimately escape into the atmosphere, leaking a gas that is more than 20 times as potent a greenhouse gas as carbon.
In the case of hydrogen, the safety implications are much worse; combusting on contact with oxygen, in the event of a leak during bunkering or from tanks or pipes, it risks catastrophic damage to vessels if it is not safely vented into the atmosphere.
Ammonia is highly toxic, evaporating at ambient temperature and pressure to form a gas that can cause blindness and permanent lung damage or suffocation in high quantities; the US Occupational Safety and Health Administration sets an exposure limit of 15 minutes to any amount above 35 ppm.
“Thirty years may seem like a long time to sort things out,” Ørbeck-Nilssen said. “But in an industry famous for playing the long game with assets designed to be profitable for 25 years, the race is on.”