Anyone in the trucking industry who is looking forward over any period beyond about 12 months ahead, will be starting to think how the freight task they are handling now can be handled in a zero carbon emissions form, and some of those contemplating this issue will be looking for a miracle.
At the moment trucks running around over the large distances between our capital cities or in the rural trucking across Australia are dependent on an extremely efficient energy source. That energy source, diesel, can be stored in a compact form on the chassis of the truck and is used to power a diesel engine, which can achieve over 50 per cent thermal efficiency. That is, it can turn over 50 percent of the energy stored in the diesel tank into motive energy at the flywheel and into the drive line.
As we all know, the idea of replacing those diesel tanks with batteries and expecting electric power to solve all of those freight transport problems outside of our major cities it’s not going to work. At the moment, the fuel alternatives in vogue are both powered by hydrogen. One is the fuel cell driving an electric motor and the other is an internal combustion engine (ICE), which uses hydrogen instead of diesel to provide the motive power.
It is going to be very difficult to work out which of those two alternative technologies may be most effective in Australia in general, and in rural areas in particular. The fuel cell is a particularly complex piece of gear and comes along with its own issues around effective cooling.
On the other side of the coin we have the hydrogen ICE, which is closer to the current technology we use, but does come along with its own complexities including spark ignition of the fuel in the cylinder. The hydrogen combustion engines which have been unveiled so far do not have the high energy thermal efficiency of the diesel and may not be able to achieve the higher horsepower numbers we are used to today in the big block diesel.
Just to make it even more difficult to make a educated decision now about future technology, there is also the choice between using hydrogen gas or liquid hydrogen as a fuel. Both of them have their advantages and issues around the kind of fuel storage used may be the crux of many arguments about dimension and mass legislation, going into the next couple of decades.
The fact of the matter is hydrogen as a gas is easier to work with and it’s a technically simpler process, but it comes with one major caveat. Storing the amount of energy we would require on a road train, on a truck, would require a great deal of extra chassis and body length. You need a lot of space to store enough hydrogen to do the job. These tanks are also heavy, a tank holding 10kg of the gas can weigh over 250kg.
However, the liquid hydrogen also comes with a number of issues which may detract from its initial appeal. The hydrogen tanks for liquid hydrogen required on a truck pulling a road train would not be that much bigger than the current fuel tanks being used on our diesel road trains today, but the liquid hydrogen is obtained by refrigerating hydrogen gas to -253°C in a process known as cryogenic liquefaction.
Looking at all of the options, asking the question, ‘what is the zero carbon technology for Australian trucking’s future?’ does not have a simple answer. The actual answer is probably, ‘All of the above’. We are going to go from a single technology industry to one using three or even more, across different tasks.
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