Prime Mover Magazine

Looking for Alternatives

Looking for Alternatives

Prime Mover continues the search for a low carbon truck. When a carbon tax is introduced, this will be in even greater demand than ever before. This month we look at a range of alternative fuels.

The entire field of alternative fuels has been filled with confusion and misinformation for many years. For the trucking industry, there have been a number of alternatives spoken about, often with a failure to actually deliver. Viable alternatives to diesel have struggled in the face of inconsistent government support, wild variations in fuel prices, and in some cases, inaccurate claims about products which cannot be backed up.  

There is a long list of alternative fuels which have been offered to the trucking industry over the years or may be offered in the future and all of them have their advantages and disadvantages. Often the easiest to use proves to be ineffective, while those which can achieve genuine results are either very expensive or impractical. When calculations are made by operators to weigh up the cost of switching to an alternative source of energy against the realistic results they can expect to receive, many decide it would be safer to stick to diesel despite all of its problems, including its carbon dioxide emissions.  

When analysing the effectiveness in carbon terms of these alternative fuels, the entire supply chain, from production all the way to their use in a vehicle need to be considered. A fuel may burn efficiently in an engine and produce lower levels of carbon dioxide in its exhaust, but high levels of carbon may have been produced during its extraction or production. The sum effect of its use on the amount of greenhouse gas in the atmosphere has to be included in any calculation.  

The number of products available now or expected to become available in the future have grown steadily over the years as the increase in fuel prices and worries about climate change have stimulated increased research into alternatives and increased the viability of other fuels.  


Natural gas has probably been the most successful alternative fuel in the last decade. It has several advantages, primarily its availability. Australia has massive natural gas reserves which are being tapped for the export market, but there is plenty left over for domestic consumption, including use as a transportation fuel. The gas is available in two forms, compressed and liquefied (CNG and LNG).  

In greenhouse gas terms, natural gas offer a reduction in the production of carbon dioxide of between 10 and 30%. This reduction is due to the combustion characteristics and the chemical make up of the fuels. Diesel has more carbon in its make up and produces more carbon dioxide equivalent as a result.  

CNG had made the biggest penetration into the Australian market, especially when fitted to buses in metropolitan areas. The gas can produce good results in terms of cost per kilometre travelled and also shows much improved emissions performance, as particulate matter is zero and nitrogen oxides are produced at only 0.2g per kilowatt hour (lower than Euro 6 requirements), as well as the lowered production of carbon dioxide.  

A drawback with using CNG however is its storage. Fuel tanks take up a great deal of space on a vehicle and the storage tanks are relatively heavy. This has limited the vehicles use to urban areas where the vehicles’ short range is not an issue and vehicle tare weight is not critical. The fuel’s environmental credentials also help local government fleet owners in their relations with the city population.  

Liquefied natural gas does solve some of the problems encountered when using CNG, but brings about some problems of its own. As the gas in a liquefied form, its storage is much more compact. Although LNG tanks take up more space than conventional diesel tanks, it is possible to run the vehicles on longer linehaul type routes. However, storage on the vehicle is complex and expensive. Instead of the simple gas bottles found in CNG vehicles, LNG must be stored at a very low temperature (-161°C) in cryogenic storage tanks. LNG vehicles also require a small diesel tank as the fuel is injected to provide combustion ignition for the LNG.  

While CNG engines use a gas regulator to introduce the fuel to the engine and a spark plug to provide the ignition, the LNG engines coming into Australia use the Westport system, where a smaller amount of diesel is injected during the compression stroke alongside the gas to provide compression ignition, like a conventional diesel engine. When comparing LNG and CNG engines, in carbon footprint terms, the LNG engine is a better performer, the direct fuel injection technology ignited by diesel compression is much more efficient and burns cleaner than the gas air mix ignited by a spark plug in a CNG engine.  

Both natural gas solutions are more expensive than their conventional diesel counterparts. The extra cost for the vehicle plus the expense of setting up refuelling facilities in depots set this alternative at a considerable premium. Any operator committing to run an LNG truck can expect to be paying a premium of between $150,000 and $200,000 on each prime mover. There are some cost advantages however, both forms of natural gas come relatively cheap when compared with diesel. CNG can be sourced in most areas of the country, direct from a normal gas main.  

Broadly speaking, the use of CNG and LNG has proved effective for certain operators. The operation involved has to work with the limitations of access to fuel supply and range to make it worth considering. The imposition of some form of carbon tax in the near future will make the calculations when choosing either form of natural gas more attractive, as operators get some form of financial return for producing lower greenhouse gas emissions.  

The big problem of access to fuel supplies is being overcome by transport operators through an innovative joint-venture scheme with BOC in Tasmania. A number of operators running regular routes have committed to investing in LNG fuelled vehicles and in return BOC is setting up a number of strategically placed refuelling facilities around the island.

EVOL LNG, which is owned by Wesfarmers, presently supplies LNG to nearly 200 vehicles in Victoria and Western Australia. It has already established its LNG refuelling infrastructure, with refuellers in the Melbourne and Perth metropolitan area, a gold mining centre in Kalgoorlie and an impressive 1200km transport route between Perth and Newman that services the Pilbara region. To meet the growing interest in LNG, EVOL LNG Manager Brad Lowson says the company is now looking to replicate this supply chain on the east coast.

Another advantage of buying natural gas involves the consistency of the cost to the operator. Normally gas supply contracts cover a number of years and involve a set price for the product throughout the period of the contract. In periods of uncertainty about fuel prices, disadvantage can carry a lot of weight.  

Mr Lowson advises customers do not typically include a carbon tax savings calculation when considering investing in LNG-powered trucks. They look at the long term cost savings and assessing the technology for its future viability in a higher fuel price environment.

“A B-double covering 250,000 km per year will save about 100 tonnes of carbon dioxide equivalent in a year,” says Mr Lowson. “The figure being discussed is approximately $25 per tonne of CO2, so that’s only about $2500 of carbon tax saved. First and foremost, customers are typically interested in the economic benefits; a secondary consideration is the marketing benefits associated with being seen as ‘green’. I’ve never seen anyone deviate to pick up the green bag.”  

The development of LNG in Australia seems to be building up a head of steam in 2010. Although only 10 or so Westport LNG engines, based on the Cummins ISX, are currently on Australian roads, over 30 are expected to come on stream later this year as the BOC project in Tasmania ramps up.  


Liquefied petroleum gas (LPG) has proven extremely successful in the car market, providing cheap fuel for larger gas guzzling engines. Its introduction into the trucking industry has proved less successful and more problematic. Trucks converted to using LPG often require high quality fuel with a minimum of 90% propane, which is not always easily accessible on the highway. In carbon dioxide terms, LPG produces more greenhouse gases than diesel because fuel efficiency can be up to 30% worse and it is produced from fossil fuels.  

Bio diesel

High hopes were held for bio diesel when discussions about alternative fuels first came to public notice. They do have a number of attractive characteristics when considering them as an alternative to diesel. First and foremost is the fact that using one hundred percent bio diesel or ethanol as a fuel reduces greenhouse gas production to nothing. Because the fuel is produced from naturally grown oils, burning the fuel simply returns carbon dioxide used in growing the original plants back to the atmosphere.  

However, bio diesel does have some disadvantages, especially when used at 100%. It can create issues within the diesel engines in which it is being used. Fuel filters will often block as the new fuel cleans out the fuel system, and operators who use the fuel all the time have had to drastically reduce oil change intervals to compensate for issues caused by the fuel’s use. Fuel consumption is also higher when using bio diesel, limiting the range of some vehicles.

Bio diesel has been sold more effectively as an additive to normal diesel fuel. Mixtures varying from between 5% and 20% (B5 and B20) have been passed as acceptable by engine manufacturers, avoiding warranty issues associated with higher concentrations of biofuel.  

By using a lower concentration of biofuel in diesel, operators still gain an advantage when it comes to calculating the costs involved in whichever form of carbon taxation is introduced to Australia over the next couple of years. Carbon dioxide production can be reduced by up to 20%.  

Other alternatives

Other fuel technologies are on the horizon and being developed around the world by different truck and engine manufacturers. These include dimethyl ether (DME), ethanol, diesehol and hydrogen – but use of these alternative fuels also feature the same types of pros and cons that need to be considered. Those which achieve excellent environmental and greenhouse gas results are also the most expensive and difficult to access. 

DME has shown some promise as a viable alternative fuel. In Japan, Isuzu has been running a long-term trial and Volvo has recently commenced a long-term trial in Sweden. Although DME creates very low exhaust emissions of particulates and nitrogen oxides, its carbon footprint is very similar to the diesel it replaces. Storage is not an issue, it needs to be held in pressure containers but only at five bar. However, its energy content is just half that of diesel, limiting range. 

The Volvo trial will have some impact on the production of carbon dioxide as the trial is using what is known as Bio-DME. This is a fuel which is not derived from natural gas but instead produced from waste derived from the forestry industry in Sweden. Coming from a plant-based raw material reduces its carbon impact by 95%.

Hydrogen has long been touted as the ultimate zero emission fuel and trials are running around the world with commercial vehicles, many of them buses, powered by a fuel cell using hydrogen as a fuel. This system produces zero emissions both in terms of particulates and nitrogen oxides and in terms of carbon dioxide.

However, there is one major drawback, the system is extremely expensive and until the cost of building the fuel cells is dramatically reduced, the economics of using the zero emission vehicles means they are not viable. The goal of viability still appears a long way off and development programmes for fuel cells are still long-term rather than short-term.

Alternative fuels have long been touted as providing a ‘green’ solution for the transport industry. However, in economic terms they are unlikely to make much impact on how much carbon taxation costs a truck operator. Often the capital outlay or increased operating costs will outweigh any monetary saving in carbon trading terms.

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