Hydrogen as an Energy Vector for Transport – The Potential Silver Bullet
Hydrogen systems for transport have the potential to revolutionize the way we power vehicles, offering a clean, efficient and sustainable alternative to traditional fossil fuels. Advanced onboard hydrogen storage systems can offer acceptable vehicle ranges while refueling times are comparable to those of liquid fuels. It is no surprise then that there is tremendous interest in the use of hydrogen as a fuel with forecasts showing that the number of light-, medium and heavy-duty vehicles by 2030 could globally be more than 4 million. To make hydrogen a practical solution for transport, there are several key challenges that need to be addressed, including the development of efficient and safe hydrogen storage systems and the optimization of powertrain solutions either via fuel-cell or combustion approaches.
Major automotive suppliers such as Bosch, Forvia, Michelin, Plastic Omnium and Schaeffler amongst others, are making substantial investments in the hydrogen space. Forvia, who has embraced the entire on-board hydrogen value chain together with its partner Michelin and formed the JV Symbio, believes that hydrogen vehicles will be cheaper than electric vehicles by 2030. Furthermore, other than a need for platinum, hydrogen vehicles will not have the extent of precious metal dependence suffered by electric vehicles. Hydrogen vehicle component suppliers are reporting that they are working on a huge number of RFQs. At this point the market is certainly showing no signs of a slowdown. Hydrogen-based approaches are finally coming to market.
A major obstacle to the use of hydrogen is supply availability of the fuel. Huge investments are going into electrolyzers to produce so-called green hydrogen. However, the extent of current levels falls far short of projected demand. Suitable refueling stations for the different vehicle segments are also required. Government investments and incentives will be key to realizing a sustainable market. It has been estimated by industry sources that for a net-zero carbon emissions world in 2050, hydrogen can help meet the world’s energy demand by between 5 and 22 percent (www.wbcsd.org). Major investments will be required in the complete hydrogen infrastructure from production, to logistics, to use.
There are several options for using hydrogen on-board a vehicle such as compressed gas or liquid hydrogen storage together with an electrochemical or thermomechanical powertrain approach. In general, system/component approaches are easily scalable between vehicle types. Toyota for example, has demonstrated how the basic technologies used on the latest generation Mirai can be scaled to other mobility segments such as medium- and heavy-duty trucks, buses and trains. Major efforts now focus on substantial cost reduction (> 20%) of all system components.
One of the biggest challenges facing hydrogen fuel cell vehicles is the development of cost-effective and safe hydrogen storage systems. Hydrogen has a lower volumetric energy storage density compared to gasoline and diesel but can have a significantly higher gravimetric energy storage density. Compared with high voltage batteries, the energy storage density of highly compressed hydrogen or liquid is orders of magnitude higher.
There are currently three main methods of hydrogen storage: compressed gas, liquid, and solid-state storage. Compressed gas and liquid-state are finding commercial applications. Solid-state storage is a promising technology that could potentially offer much higher energy densities and safety, but it is still in the early stages of development.
Other areas of development are hydrogen-based powertrains. Both fuel-cell and hydrogen combustion approaches are receiving attention by major OEMs and system suppliers. Both approaches have several benefits and drawbacks as listed in the exhibit below.
Source: The ITB Group, Ltd.
Fuel cells convert hydrogen into electricity to power an electric motor, producing only water as a byproduct. This technology has the potential to be highly efficient and clean, but there are still several technical challenges to overcome. One key challenge is the durability and cost of the fuel cell stack, which is the heart of the fuel cell system. The fuel cell stack must be able to operate at high efficiency for tens of thousands of hours and be cost-effective to produce at scale. Additionally, fuel cell vehicles require an efficient energy management system to optimize the use of the fuel cell and battery, as well as regenerative braking and other efficiency measures.
Hydrogen combustion engines may have unacceptable nitrogen oxide emissions, but these can be reduced with well-known exhaust system approaches such as selective catalytic reduction systems. Some OEMs such as Porsche, have demonstrated that with proper design, raw engine-out emissions may be at acceptable levels.
Despite these challenges, there has been significant progress in the development of hydrogen systems for transport in recent years. The number of OEMs offering vehicles continues to increase. Just a few examples include cars (BMW, Honda, Hyundai and Toyota), trucks (Daimler, Hyundai, Hyzon, Kenworth, Nikola and SANY) and trains (Alstom and CRRC).
In conclusion, hydrogen systems for transport offer a promising path towards a clean and sustainable future, but there are still significant technical and infrastructure challenges that need to be overcome. Continued investment and research is required to address these challenges and to make hydrogen a practical and cost-effective solution for powering vehicles.
ITB has dialogue with companies throughout the mobility value chain to determine unmet needs and innovations for improved hydrogen systems. ITB’s 2023 research and analyses will be offered in a new report Hydrogen Systems for Transport. For further information please contact us.