A traditional 40L steel tank weighs around 60kg, while a composite Type IV tank can weigh as little as 20kg. Every 100kg of vehicle weight reduction reduces CO2 emissions by 10 g/ km, helping manufacturers to avoid the €95 per vehicle penalty.
Low permeation to reduce methane emissions But weight reduction is only part of the solution. Indeed, while lightweight composite Type IV tanks contribute to a better fuel economy compared to steel, they carry the risk of methane permeation. Since methane is a greenhouse gas (GHG) with 25 times higher Global Warming Potential (GWP) than CO2, its emission to air constitute an extra burden on climate change. Permeation of this gas represents a concern not only for the wellbeing and the comfort of the passengers but also for the environment. Type IV tanks need a liner made from an eff ective barrier material to prevent the permeation of this greenhouse gas. Akulon Fuel Lock provides a liner material that reduces methane emissions by a factor of at least 150 compared to conventionally used HDPE, enabling the use of Type IV tanks inside passenger cars. The assessment of the environmental impact of a CNG tank over its entire life cycle – from manufacturing to end of life, including its use in the vehicle for 10 years or 230,000 km – shows that moving from a steel Type I tank to a Type IV tank with an HDPE-based liner of 3mm wall thickness would decrease the total global warming potential of only less than 10%, due to HDPE’s poor performance as a methane barrier.
Thermal properties
250 200 150 100 50 0
225 180 125 86 125 132
HDPE
Akulon Fuel Lock ■ Tmelt ■ Tsoftening@0.45[Mpa] ■ VICAT
Akulon Fuel Lock is designed to handle the required elongation at low temperature, while also meeting the required impact performance during drop tests to comply with ECE R110. The material successfully passes the pressure cycle test at -40°C with >10,000 cycles and withstands extreme fast-fi lling at -40°C. Akulon Fuel Lock’s high-temperature performance exceeds HDPE in dimensional stability (soſt ening/creep), ensuring leak tight tanks at high temperatures in cars of up to 90°C.
Global Warming Potential (GWP) of a CNG tank over its entire life cycle
900 800 700 600 500 400 300 200 100 0
■ End of life ■ Methane permeation ■ Transport emissions ■ Manufacture
Akulon Fuel Lock: A drop-in replacement Akulon Fuel Lock exhibits extremely high parison stability in the blow molding process. The parison stability allows to move towards a very narrow wall thickness distribution of 2.0 ± 0.1 mm for a 1 m long parison of 5 kilograms. The material can be processed on blow molding equipment suitable for HDPE with a L/D ratio of 25. In addition, cycle times can be reduced by 10 to 20% over HDPE. Direct inline re-use of up to 50% scrap has no eff ect on the parison stability or material performance. Akulon Fuel Lock is also available for injection molding and extrusion, giving you the freedom to design in virtually any confi guration, and the ability to produce tanks for heavy-duty vehicles. In addition, DSM off ers both design and on-site technical support so you get the maximum return on your investment.
Steel HDPE Akulon
On the contrary, lining the tank with Akulon Fuel Lock (1.5mm wall thickness) would reduce GHG emissions up to more than 40% compared to steel. In addition, the potential reduction in wall thickness can increase tank volume by as much as 1.5L for a 40L tank, signifi cantly extending the range. Akulon Fuel Lock proves to be the most eff ective barrier, empowering the automotive industry to make full use of CNG as a future fuel for vehicles with lightweight construction and decreased impact on the environment.
Safety is always a primary concern Akulon Fuel Lock is a successful liner material because of the balance it strikes between low-temperature performance (down to -60°C) and low permeation, all while maintaining good processability. Tank temperatures drop to -60°C during the fast- fi lling process, causing shrinkage in the liner. At the same time, the pressure increases rapidly, resulting in fast expansion of the liner.
A proven track record Akulon Fuel Lock enables safe use of lightweight composite tanks with an extremely low permeation level. The Akulon Fuel Lock portfolio consists of a number of impact modifi ed, high barrier, polyamide 6 material grades for injection molding, blow molding and extrusion. These commercially available materials have been tested and used in this fi eld of applications for several years without any accidents or issues. Akulon Fuel Lock is used in tanks that comply with ECE R110.
kg CO2 equivalents
temperature [˚C]
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