How to create strong yet lightweight hydrogen fuel tanks for electric vehicles
The bulk of industry experts agree that vehicles based on internal combustion engines will disappear over the next 20 to 30 years. While a few electric vehicle pioneers like Tesla have moved into the market aggressively, most OEMs are still producing vehicles with internal combustion engines. They are using the income from these vehicles to fund the development of electronic vehicle innovations and new mobility concepts as we move toward the age of connected cars and autonomous driving. As an in-between step, car manufacturers will continue to produce hybrid internal combustion engine/electric vehicle technology with combustion performance improvements aimed at reducing fuel consumption, as well as CO2 and NOx emissions.
In the move to fully electric vehicles, many car manufacturers are banking on lithium-ion batteries (LiBs) as the power source. Yet one group of OEMs – primarily based in Japan, Korea and Germany – are exploring the option of hydrogen fuel cells, in part because of the geopolitical reality of not wanting to rely 100% on China, and in part because some characteristics of fuel cell technology are compelling in their own right. The alliance that installs more stations faster will gain a competitive advantage, however we can expect that the electric vehicles of the future will rely on both technologies.
While the efficiency of fuel cells lags behind LiBs, fuel cell technology does have the following advantages:
- We can replace heavyweight batteries with a stack of fuel cells
- Fuel cells charge up to six times faster than LiBs
- Fuel cells offer a longer driving range (though the range on LiBs is increasing quickly)
- Fuel cells move away from a reliance on lithium, mainly sourced from China and Chile and which may not be in sufficient supply to support the entire electric vehicle industry, and cobalt, two-thirds of which is sourced in the Republic of Congo.
To pave the way for hydrogen infrastructure, a number of significant alliances have recently been announced. In Europe, Shell has invested in the world’s largest hydrogen production facility in Wesseling, Germany, which will be operational in 2020. At the same time, a joint venture is targeting having 400 new H2 fuel cell stations in Europe by 2023. In Japan, a joint venture is targeting the installation of 300 H2 fuel cell stations by 2025. In the US, a partnership targets introducing a fleet of 40-tonne heavyweight trucks with a 3000km range to US transport routes by 2021. And in China, the country’s most recent Five Year Plan targets the introduction of 3000 H2 fuel cell stations in China by 2030.
Fuel cell technology produces power when the hydrogen reacts with oxygen from the air to produce water vapour, heat and electricity. Since the source of energy generation is permanently on-board the vehicle (as opposed to batteries, which store electricity produced by other means), the size of the battery on fuel cell-driven vehicles can be significantly reduced. One concern with this technology is that the hydrogen needs to be transported in large tanks that can withstand internal pressures of 700 bar or more. Hydrogen fuel cell tanks have traditionally been made from steel, and are therefore very heavy. Yet it is possible to create a lightweight hydrogen gas tank using engineering plastics.
DSM has already launched a lightweight Compressed Natural Gas (CNG) tank that combines a blow-molded inner liner made from Akulon polyamide 6 (PA6) with an outer composite structure made from EcoPaXX polyamide 410 (PA410) tapes. The inner tank eliminates the escape of hydrogen by evaporation, while the outer composite structure protects against the high burst pressures essential for hydrogen storage. The combined solution provides excellent mechanical performance at temperatures rom -40°C to 85°C – superior to the performance of competitive aromatic polyamides. It outperforms competitive materials, demonstrating very good compatibility with hydrogen, higher burst pressures, and better economics. At the same time, the solution is fully recyclable.
To learn more about how to create strong yet lightweight hydrogen fuel tanks, download the full white paper here.