Truck transport accounts for roughly 25% of energy used in the global transport sector, making it a substantial contributor (2.6%) to worldwide greenhouse gas emissions.
As concerns about greenhouse gas emissions continue to escalate, the introduction of zero-emission technologies within the freight industry is vitally important.
Here at RMIT University, we’ve developed new technology that, we believe, will push us further toward a sustainable and future-ready freight industry.
An industry under threat
Australia has some of the highest road lengths and freight levels per capita in the world. In fact, road freight transport is a $35 billion dollar industry here. Given the sheer size of the Australian land mass, the distance between major cities, and the lack of a feasible rail alternative, road freight is crucial to trade and commerce.
With the price of diesel fuel rising considerably in the past decade and the possible expansion of the carbon tax to include fuel for trucks, those in charge of the freight industry worry their industry is under threat. Low-carbon alternatives to the current fleet are needed.
A possible solution to the problem, and one that we’ve been working towards, is the development of hydrogen fuel cells to replace traditional diesel engines in trucks.
Hydrogen power
Hydrogen fuel cells work by taking hydrogen gas (H₂) and combining it with oxygen (O₂) to generate an electrical current (and water and some heat as byproducts).
The hydrogen gas is produced through a process called electrolysis (or breaking down) of water using electricity from renewable sources such as wind and solar.
A zero-emission solution of this kind (in both hydrogen production and consumption) could play a key role in addressing the environmental, economic and social factors that will influence the sustainability of the truck industry in the future.
Zero-emission alternatives
Electric battery technology is another zero-emission option that could potentially be used in the transport sector (if charged using electricity from renewable sources). But this technology might not currently be suitable for the truck industry due its low energy storage capacity. For example, existing battery technology doesn’t allow trucks to cover the distance from Melbourne to Sydney on one charge.
Biofuels, including ethanol, various bio-oils and biodiesel, provide another alternative transport fuel. “Second-generation” biofuels are likely to play some role for transport in future, but the amount of crops and land available for biofuel production will be severely limited.
Enough crops and land need to be set aside to supply food for a growing world population, and there are also constraints on available land, water and fertilisers needed to grow “second-generation” fuel crops.
But we focused on hydrogen …
Here in the School of the Aerospace, Mechanical, and Manufacturing Engineering at RMIT, we’ve recently developed Australia’s first model of a fuel cell truck running on hydrogen stored in metal hydride bottles on board the truck. The truck model is an exact replica (1/14th scale) of the Scania Highline series, operated using a remote control unit which simulates the performance of a typical long-haul truck used in Australia (from Melbourne to Sydney, for example).
A range of measurement instruments have been designed for and installed in the model, all of which are connected to a wireless data acquisition system. This system remotely monitors the truck’s performance and collects critical data such as the rate of hydrogen consumption and the electrical power supply in real-time.
By measuring the performance of the model under pre-defined dynamic loads and scaling up the results using purposely-developed mathematical models, the performance of a full-scale hydrogen fuel cell truck can be simulated and predicted.
What now?
In the early days of our research and development, we’ve highlighted some of the technical, economic and social challenges facing the commercialisation of this technology.
A key technical challenge is the development of cost-effective hydrogen storage systems that can carry enough hydrogen on board and provide desirable driving range (again, Melbourne to Sydney is a good example). Various materials/technologies for onboard hydrogen storage are currently being researched and developed to overcome this barrier.
Such technologies include high pressure hydrogen (at 350 and 700 bar, liquid hydrogen and chemical hydrides.
Hydrogen production and distribution are other areas to be considered for further technological development. Hydrogen fuel cells and the required renewable energy technologies for zero-emission production of hydrogen are currently too expensive for commercial development.
That said, the price of hydrogen cells is dropping – they cost roughly $2,000/kilowatt at the moment and that will probably drop to less than $100/kilowatt within 15 years.
Given this current downward trend in prices and the likelihood of such cells being mass produced within a decade, such technologies might not be restrictively expensive in future.
Perception power
Of course, there are also social barriers to be overcome. In particular, there is a public perception that hydrogen is unsafe and unreliable as an energy carrier. The demise of the Hindenburg in 1937 is largely to blame for this perception.
In reality, hydrogen has been proven safer than liquid fossil fuels such as diesel and petrol, if handled properly and if appropriate safety measures are taken.
So while there are still significant challenges to overcome before we see hydrogen-powered trucks on Australian roads, we’re certainly moving in the right direction.