Updated on the 1st of December, 2020.
If the shipping industry were a country, it would be the 6th biggest contributor to climate change in the world.
Ocean liners, of which thousands carry billions of dollars of goods every year via every ocean on the planet, are mostly powered by petroleum-based heavy fuel oil (AKA bunker fuel). Heavy fuel oil emits carbon dioxide (CO2), sulphur, and nitrogen-containing compounds, which not only get stuck in the atmosphere and cause the greenhouse effect, but also contribute to smog, respiratory illness, and ocean acidity.
In 2012, the overseas shipping industry produced 960 million tonnes of CO2.
But the International Maritime Organisation (IMO) wants to change that. One of the leading trends of the transport industry in 2020 is the IMO ban on fuels with over 0.5% sulphur content, in an effort to decarbonise the shipping industry by 50% - compared to 2008 levels - by 2050.
Maersk, the biggest shipping company in the world, has promised to completely decarbonise by 2050.
Limiting emissions from fuels is the primary way Maersk and the IMO intend to work towards this goal. Some researchers have found that installing hydrogen fuel cells on ships to replace heavy fuel oil would help with this.
How do hydrogen fuel cells work?
Usually, ships are powered by burning fuel to create heat, which is used in a combustion engine to convert into energy. Hydrogen fuel cells split this reaction in half, creating heat to convert into energy without burning fuel.
Hydrogen fuel cells are built inside an electro-chemical cell, which is a box, basically, where you insert a positively charged electrode on one side of an electrolyte (usually water, but sometimes a membrane electrolyte) and a negatively charged one on the other. These electrodes act as a catalyst for hydrogen ions to flow through them freely.
Insert hydrogen. The hydrogen atom will split into two positively charged hydrogen ions and two electrons. As they move through the cell, the positively charged hydrogen ions will recombine with oxygen to produce water. The exhaust from the fuel cells is moist air, with no greenhouse gasses. Some ships have even used this for their drinking fountains onboard.
The electrons will travel through a wire, creating an electrical current you can use.
You can use as many cells as you like and link them all up. The only limits to how much power you can produce are how much hydrogen you have and how many cells you can fit on your ship.
There are two problems with hydrogen fuel cells: how much hydrogen you have, and how many cells you can fit on your ship.
In order to decarbonise the shipping industry with fuel, you need to use fuel that produces no carbon dioxide. Hydrogen fuel cells don’t produce carbon dioxide, but the process of making hydrogen for the fuel cells does.
The most common method for producing hydrogen is Steam Methane Reforming (SMR), which produces carbon monoxide and hydrogen, then the carbon monoxide produces more hydrogen and carbon dioxide. Other methods include biomass gasification (heating up plants), which also produces CO2; electrolysis (splitting water molecules with electricity), which may use CO2 depending on the electricity source, and fermentation, which is using bacteria that produce hydrogen as part of their metabolism.
To make hydrogen production carbon neutral, manufacturers could use renewable energy during electrolysis, sources of which include sunlight, heat or algae. Manufacturers could also opt for fermentation as a more commonly used method of hydrogen production.
However, as it is, hydrogen fuel cell production still emits much less in greenhouse gas emissions than traditional fuel sources.
The next problem is fitting ships with hydrogen fuel cells. Ships last a long time and are very expensive, so replacing them with ships built with hydrogen fuel cells straightaway would be a massive waste of money. Waiting for companies to have to buy new ships to implement carbon-reducing technologies, however, is a massive waste of time.
So, the question is: can ships that are already in service have their combustion engines converted to hydrogen fuel cells using technology that already exists?
The answer is yes. But it might take up too much space.
Hydrogen is much less dense than heavy fuel oil, which means weight isn’t so much a problem as space. A study by HyMARC explored three different ways of storing hydrogen that already exist: batteries, hydrogen gas fuel cells, and liquid hydrogen fuel cells. They found the liquid hydrogen fuel cell option was the most practical, leaving the most space for cargo out of the three.
It would be possible to retrofit most types of existing vessels with hydrogen fuel cells, and even easier to build new ships with them.
Hydrogen is twice as efficient as diesel engines but takes up four times the space. Ships would then have to make room for twice as much space for fuel cells than a diesel engine, reducing the space they have for cargo. Companies like Maersk have found more customers choosing to ship with them because they’re going green is well worth the space sacrifice.
What is Australia doing about all this?
Globally, regulatory bodies and state-owned shipping companies are the biggest advocates for zero-carbon shipping, but independently operated companies are also seeing the benefits.
The governments’ role in decarbonising shipping includes finding ways to make zero-carbon solutions more cost-efficient than heavy fuel oil with market regulation and infrastructure.
Australia is seeking to export hydrogen to countries that don’t have the resources for solar, hydro or wind renewables. Our government is testing out the efficacy of using sustainably-generated hydrogen to export liquified ammonia, already a major export product due to its use in fertiliser. Passing ammonia over a hot catalyst gives a mixture of residual hydrogen and nitrogen. That’s hydrogen we can use.
The future of carbon emissions in the ocean shipping sector has been compared to Pascal’s wager. It states if you don’t believe in heaven you should act like you do. If you’re right, you get in, and if you’re wrong, you’re dead anyway, so what does it matter?
If shipping companies don’t believe government regulation will step up on climate change, shipping consultants say they should act like they do. If they’re right, they get ahead of the game in terms of being allowed to ship. If they’re wrong… Well, climate change has already caused more problems at ports than would otherwise occur, with more catastrophic events like cyclones, flooding and other natural disasters either delaying shipments or destroying goods and ships alike. No action on climate change might mean the end of the shipping industry altogether.
Researchers predict the hydrogen fuel cell takeover will be underway by 2030, as ships prove the efficacy of hydrogen fuel cells by 2025.
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