Article published in the European Files.
The automotive landscape is evolving more quickly and more fundamentally than ever driven by societal and environmental changes. We can help meet these challenges using new powertrain technologies, developing lighter vehicles, optimising energy management, and improving end of life recycling.
Durable plastics, including polyolefins – polypropylene and polyethylene – are an increasingly indispensable part of modern transportation, supporting the reduction of CO2 emissions through their low density and lightweight. They are also inherently recyclable, ensuring a sustainable end-of-life performance. However, the use of plastics in vehicles is only the beginning: polyolefin based solutions address many of the challenges associated with both current and future mobility.
If we start with the vehicle itself, a basic principle applies: no matter the energy source, a heavier vehicle will need more energy to get from A to B. Energy consumption comes from a number of factors:
- Base electric load (heater, air condition, music system, etc.)
- Power to overcome aerodynamic drag or air resistance
- Power to overcome rolling resistance of the wheels
- Power to work against gravity when driving uphill
- Power for overcoming inertia in acceleration
Until very recently, each generation of cars has been, with a few exceptions, heavier than the one before. That is because carmakers continue to add more functionality, whether it be in the form of extra safety features, comfort, or infotainment. Weight saving is therefore increasingly important: when you save 100 kg of vehicle mass, the fuel consumption is reduced by approximately by 0.4 l / 100 km or by 10 grams of emitted CO2 per kilometre. Therefore, decreasing the vehicle weight by 1 kg means 0.1 g/km of CO2 emissions less or a penalty saving of 9.50 EUR (based on EU legislation mandating emission reduction targets for new cars in 2020 of 95g/km).
As society starts the transition to cars that gain some or all of their power from electricity, we are faced with the prospect of even heavier vehicles. The internal combustion engine may be taken out, but in its place comes an electric motor and, most importantly, heavy batteries. New Energy Vehicles (NEVs) all benefit from optimised use of electricity to maximise performance and increase vehicle range.
Polypropylene is the leading plastic for light weighting of vehicle parts on both the interior and exterior, substituting commonly used metals and more dense engineering plastics. When combined with novel technologies, including lightweight fillers (wood or carbon fibre) or foaming of polypropylene, density reduction and related weight saving of up to 25% can be achieved, depending on the vehicle part.
Lithium-ion battery range is the key battleground in the NEV market. Polyolefins are an important contributor to improving their performance – and also their safety. They are used to produce microporous permeable membranes between a battery’s anode and cathode, for example. Polypropylene films are also used in capacitors that transform the direct current from the battery into alternating current for the motor. Polypropylene is also being explored as a lightweight solution for many parts of the battery itself, including cell trays and housings. NEVs and traditional internal combustion engine vehicles can contain up to a kilometre of wires and cables of different types; halogen free polypropylene wiring solutions are a safe and high strength alternative across the operating temperature range of a NEV.
However, we also have to remember that NEVs will be dependent on the energy grid. Polyolefins today play a critical role in energy transmission, ensuring tomorrow’s NEVs can be powered by clean electricity from renewable sources like wind and solar. Offshore wind farms are increasingly further away from the coast, and hence sub-sea high voltage direct current power cables are an attractive solution. High purity cross-linkable polyethylene is the most effective insulator for long distance electricity transport (up to 640kV), with losses less than 3% over distances up to 1000 kilometres.
As the drive for renewable sources of energy to power NEVs advances, photovoltaic (PV) modules are another important technology. Again, polyolefins have a role to play: polyethylene solar panel back sheets and encapsulant films improve operational reliability, offering cost efficiency, extended lifetime, and a sustainable solution for PV modules.
For more than 50 years, polyolefins have played a critical role increasing safety and efficiency of transportation. As we move into the new and exciting mobility landscape, and address the challenges of climate change, the importance of polyolefins will only increase. Borealis is committed to developing valuecreating polyolefins that enable our customers to think about the material science of transportation in a different way.