As one of the world’s largest consumers of diesel per capita, Australia could soon benefit from the onshore production of a cleaner-burning alternative.
Dimethyl ether (DME) is a colourless gas used as an aerosol propellant for things such as hairspray, but engine manufacturers and other companies have been exploring its potential as an alternative transport fuel.
This is because DME is compatible with compression ignition engines, requiring only minor modifications. It mirrors the performance of diesel and, under the right conditions, has a much cleaner emissions profile, producing virtually no particulate matter or soot.
Michael van Baarle, the managing director of Australian DME Fuels, which was established in 2015, says: “Any replacement of diesel oil by DME, particularly in heavy-duty vehicles, will result in a significant improvement in air quality.”
The Brisbane-based company has plans to build Australia’s first commercial-scale production plant by 2020, generating a diesel-replacement fuel for use in trucks, heavy machinery, and remote off-grid power stations. The DME can also be blended with liquefied petroleum gas (LPG) for use in passenger vehicles.
“If you make the methanol feedstock for DME renewably, then you essentially have an almost zero-emission fuel from a greenhouse gas perspective,” says van Baarle.
There are other upsides: DME has similar storage and handling properties to LPG. This means it can be stored safely in gas bottles and distributed using existing LPG infrastructure. It also has a longer shelf-life than diesel, and poses no environmental contamination risks from spillage.
Van Baarle hopes the onshore production of DME will help Australia end its reliance on diesel, particularly for transportation and off-grid power generation.
In 2014/2015, Australia used more than 23.5bn litres of diesel, or just shy of 1,000 litres per person, according to information from the US Energy Information Administration.
This places Australia among the world’s largest consumers of diesel per capita, he says.
While compression ignition engines are efficient, burnt diesel produces greenhouse gases, noxious emissions, and particulate matter. These hazardous pollutants reduce air quality and can trigger respiratory problems.
Even with sophisticated emissions control systems, many diesel engines are still emitting noxious pollutants above legal limits, and some cities are considering banning diesel vehicles altogether.
Australian DME Fuels wants to produce DME from renewably generated methanol, which is considerably more expensive than using fossil fuel feedstocks.
This means they need access to waste CO2 from industrial processes, and an ability to make hydrogen from the electrolysis of water – a power-intensive process that would require them to purchase wind or solar energy.
This specific process for generating methanol has been demonstrated on a relatively small scale. A facility in Iceland has generated about 4,000 tonnes a year, says van Baarle.
Australian DME Fuels plans to produce 12 times that amount. “We believe that the next scale-up of this technology to commercial quantities of 50,000 tonnes per annum can be achieved in Australia,” he says.
This translates to about 48.5m litres of DME, which is roughly equivalent to 26m litres of diesel from an energy output standpoint.
With on-site hydrogen production capabilities, he estimates the plant will cost between $200m and $300m to build.
The company is exploring funding strategies, including support from bodiessuch as the Australian Renewable Energy Agency.
Van Baarle says the company is also developing a “network of strategic partners” including engine manufacturers, LPG distributors, methanol producers, and renewable power generators.
“We have some of those people already in place,” he says.
But cost is still a red flag. Renewable DME could be upwards of three times more expensive per gigajoule than diesel (currently $15/gigajoule), or DME produced with non-renewable methanol ($17/gigajoule).
Van Baarle says his company could offset that cost by selling bulk, renewably produced methanol. He’s also hopeful that downward trends in the cost of solar power will make it more affordable.
One of the key challenges to establishing a domestic market for DME is co-ordinating the deployment of modified compression ignition, or diesel engines.
Jim Patel is a research scientist at the CSIRO who has been leading an Australia-India Strategic Research Fund project investigating the small scale production of DME. “DME is often referred to as a chicken-and-egg problem,” he says.
“There is little incentive to develop applications for DME when it isn’t widely available and while there are no applications, there is little incentive to supply,” he says.
Patel says the main challenge for producing renewable DME from CO2 will be the economics of buying renewable power to make hydrogen and sourcing enough CO2 feedstock.
He suggests it might be more affordable to initially produce a proportion of DME from renewable sources and gradually increase this.
Patel says there are positive signs DME could be gaining traction internationally.
Volvo has begun developing DME-powered engines for heavy trucks in North America and its subsidiary, Mack, is running a demonstration with municipal sanitation trucks in New York City.
Last year Ford Motor Company began working with the German government to develop and test the world’s first production passenger car to run on DME.
“Due to its potential for reduced particulate emissions, DME should be amongst the alternative fuels under consideration for use in Australia,” says Patel.
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