HAVERHILL, U.K. – Carbon emissions and air quality are the two biggest environmental challenges. The transport industry produces around a quarter of greenhouse gas emissions in Europe. Consequently, regulators have imposed strict deadlines that implore vehicle manufacturers to take action right now.
From 2021, passenger vehicle manufacturers must meet a new 96 g/km carbon emission limit. This is the first time that this limit will apply to all new vehicles. Manufacturers that fail to meet the new limit will face fines (called the excess emissions premium) for every unit in excess. A recent report has suggested that as many as eight of the big 13 manufacturers will be some way off meeting the targets.
In a quest to reduce emissions and improve efficiency, automotive manufacturers are looking to reduce the fuel consumption and emissions created by their vehicles. Fortunately, the materials science industry has created some intriguing opportunities to reduce both direct (tailpipe) and indirect emissions.
By design, braking involves huge energy losses. All the kinetic energy is converted into heat in conventional braking systems. Conventional braking is also one of the leading causes of particulate matter emissions from vehicles.
Recent research in brake-disc materials has highlighted several critical features that could both lightweight the ‘unsprung’ mass of a vehicle and reduce particulate emissions. The unsprung mass of the vehicle – the weight which is not borne by the suspension – is said to have a larger impact on fuel economy than the sprung mass. Therefore, reducing this mass will make a greater improvement to fuel economy and emissions.
Cast-iron brake discs have been the norm up to now. However, a current Innovate UK project by Keronite, in combination with Alcon, has highlighted that aluminum brake discs, protected by plasma electrolytic oxide coatings, could prove the answer. They are 50 percent lighter, demonstrate very low wear and nominal particulate emissions – all while delivering the equivalent performance to a cast-iron brake disc.
Lighter regenerative braking systems
Many of today’s hybrid-electric and battery-powered cars feature regenerative braking technology, but there are still intriguing improvements possible. Regenerative brakes create fuel savings of up to three percent, simply by capturing that lost energy through an alternating current circuit, gearbox, motor and a battery. While these systems enable the capture of this energy, they also add a considerable number of components, each with a number of unique modes of failure. To ensure that the impact of this added weight can be mitigated, using a lightweight brake disc protected by an advanced-surface coating is a possible solution.