Electric vehicles’ unsustainable secret

ELECTRIC VEHICLES’ UNSUSTAINABLE LITTLE SECRET

BATTERIES ARE THE WEAKEST LINK IN THE SUSTAINABILITY CHAIN

Electric vehicles (EVs) have been heralded as the answer to transportation’s sustainability issues, providing a scalable solution for the notoriously difficult-to-decarbonise sector. However, there’s one key component that needs some work if EVs are to become a completely sustainable method of transport — the battery. Here, Simone Bruckner, managing director of automotive resistor manufacturer Cressall, investigates the dark side of EV batteries. 


The electrification of the automotive market is a necessary step to reduce greenhouse gas emissions and ward off climate change’s consequences. Every automaker is in support of the rollout, with more affordable models being released by the day to encourage consumers to make the electric shift. At the same time, governments are enforcing change through legislation that bans the sale of new fossil fuelled vehicles from as early as 2025.

The urgency of the climate crisis and looming legislation changes has resulted in the exponential growth of the EV market. A recent McKinsey report estimates that by 2035, the three largest automotive markets — the European Union, United States and China — will be fully electric. However, while driving an EV is ‘zero emission’, an unsustainable secret hides in production.

THE PROBLEM WITH BATTERIES

Traditional diesel and petrol-powered vehicles benefit from lead-acid batteries, which are widely recyclable. However, the same can’t be said for EVs, which use lithium-ion batteries instead. Typically made from raw materials including cobalt, nickel and manganese, lithium-ion batteries are extremely expensive to produce and require high levels of mining activity. 

Mining raw materials can lead to huge environmental destruction, releasing elements into the atmosphere that can contaminate soils and disrupt entire ecosystems. What’s more, lithium-ion batteries are significantly more challenging to recycle, contributing to further environmental damage if improperly disposed of at the end of their life. 

Aside from environmental devastation, lithium-ion batteries are also in short supply. Battery production capacity across the globe is expected to increase twenty-fold, but this won’t be enough to meet the expected future demand. 

Although several industry players are developing recycling methods and reducing the reliance on raw materials, any significant progress is far off. For now, to ensure demand is met and improve the output for using these materials, it’s important for automakers to consider how they can make existing batteries last longer.

EXTENDING LIFESPAN 

Automotive design engineers should consider the benefits that regenerative braking can bring in extending lithium-ion battery lifespan. A study by the Institute for Electrical Energy Storage Technology concluded that a higher level of regenerative braking usually reduces battery ageing by reducing lithium plating.

Lithium plating refers to the accumulation of metallic lithium on the battery’s anodes, which can cause irreversible damage over time and significantly reduce battery lifespan. Lithium plating is exacerbated long charging periods, but regenerative braking can help to alleviate this issue.

Regenerative braking occurs when an EV recovers energy while decelerating by using its electric motor as an electric generator and converting kinetic energy into electrical energy. This electrical energy is then stored in the vehicle’s battery, increasing range and efficiency between charges. Incrementally recharging the battery each time the vehicle brakes reduces the length of the charging period, therefore reducing the accumulation of metallic lithium and improving battery operations and life cycle.

Resistors play a crucial role in regenerative braking, by removing excess energy from the system in the event that the battery is already fully charged. This prevents overcharging or catastrophic damage to the system. Cressall’s EV2 resistor is designed specifically for EV applications and is the most compact and lightweight dynamic braking resistor model on the market, making it ideal for EVs.

EVs are central to a more sustainable transportation system but we mustn’t cite them as an answer to all of our environmental issues. Recognising the problems that they bring and considering both long and short-term solutions is necessary in order to create truly sustainable transportation. While lithium-ion battery recycling could be a viable option in the future, extending battery life through techniques such as regenerative braking is essential to see us through and reduce reliance on finite raw materials from today.

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Regenerative braking

WHAT IS REGENERATIVE BRAKING?

Imagine if you could reclaim some of the energy you lose throughout the day, without needing to rest. Did you know that electric vehicles (EVs) are able to do this through regenerative braking? An efficient way to reuse some of the energy lost as heat when a vehicle brakes, regenerative braking supports higher efficiency and the ability to travel further on a single charge.

When the driver steps on the brake pedal of a vehicle, hydraulic fluid pushes the brake pads against brake discs on each wheel. This friction slows down the vehicle, but the process also creates heat and wears away the material on the pads and discs over time.

Regenerative braking uses the excess kinetic energy to recharge an EV’s battery. It is able to do this because the electric motor in an EV can run in two directions: one, using the electrical energy, to drive the wheels and move the car, and the other, using the excess kinetic energy, to recharge the battery.

When the driver lifts their foot off the accelerator pedal and steps on the brake, the motor starts to resist the vehicle’s motion, “swapping direction”, and begins putting energy back into the battery. As a result, regenerative braking uses the EV’s motor as a generator to convert lost kinetic energy into stored energy in the battery.

A NECESSITY

The Competition and Market Authority has warned the UK government that, ahead of the petrol ban in 2030, more electric charging points must be established to make EV charging easier for road users. As it stands, there are only 25,000 public charging points in the UK. This needs to increase by tenfold to ensure EV success from 2030 onwards.

While not fundamentally an element of EV charging infrastructure, regenerative braking provides a way of making EVs more efficient by increasing the number of miles completed without charging the battery. Furthermore, the process can help make the charging less reliant on electricity from the National Grid. By reducing the frequency of charging and amount of electricity needed to recharge batteries, regenerative braking can make the entire charging process more energy efficient.

A HELPING HAND


However, regenerative braking cannot act alone. To work effectively, other technologies are needed to make the process safe and effective. If the car battery is already full or there is a failure, regenerative braking cannot happen as the excess energy has nowhere to go and must be dispelled safely. If not dissipated, it won’t be possible to slow down the vehicle. To prevent this from happening, resistors are used to collect excess energy and dissipate it safely.

Cressall’s EV2 resistor converts excess electricity into heat that can be dissipated or used in other parts of the vehicle, such as to heat the cabin, the batteries or even the fuel cell. The EV2 is a lightweight, compact resistor which manages to transfer this heat into the cooling water or glycol mix, which is already used in the cooling or heating system for different vehicle components. Cooling is achieved by pumping cold coolant liquid, which comes into one end of the unit and absorbs the heat through thermal conductivity and convection. It can then be pumped through a radiator located away from unit and cooled again to reach the starting temperature.

While it may not be possible for humans to regain lost energy without taking time out to recharge, regenerative braking enables EVs to use excess energy to work more efficiently. With the help of resistors, EV users can benefit from a longer battery life, helping to drive EV efficiency forward and ensuring safe driving in any conditions.

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Zero carbon transportation

ZERO CARBON TRANSPORTATION

HOW CAN AUTOMAKERS SUPPORT TRANSPORT’S DECARBONISATION?

In July 2021, the UK government unveiled its plan to decarbonise the entire domestic transport system to align with the net zero by 2050 target. All forms of domestic transport will be decarbonised on land, air and sea.

The electrification of the automotive market is a necessary step to reduce greenhouse gas emissions and ward off climate change’s consequences. Every automaker is in support of the rollout, with more affordable models being released by the day to encourage consumers to make the electric shift. At the same time, governments are enforcing change through legislation that bans the sale of new fossil fuelled vehicles from as early as 2025.

The Decarbonising transport: a better greener Britain report outlines how the government intends to achieve transport decarbonisation. While some of the report repeats previous pledges, it announces several new targets.

HOW HAVE THINGS CHANGED?

Since announcing its nation-wide net zero emissions by 2050 target back in 2019, it’s been common knowledge that the government wants all transport to decarbonise in the next few decades. One key initiative has been ending the sale of new fossil-fuelled cars and vans, which has been brought forward to 2030 — ten years ahead of initial plans.

In addition to bringing forward the ban on petrol and diesel cars and vans, the latest report also announces a ban on petrol and diesel heavy goods vehicles (HGVs) in 2040. This is an important step in decarbonising road transport since HGVs are some of the biggest carbon dioxide emitters, accounting for 17 per cent of road transport’s total emissions.

Although similar targets have been set for other transportation sectors, automotive is arguably in need of the greatest overhaul. The latest figures show that in 2019, the majority of greenhouse gas (GHG) emissions were from road transport. Therefore, we must take decarbonising this subsector as a top priority.

Despite significant progress, more needs to be done to create an electrified transport fleet. The electric vehicle (EV) market is growing at an exponential rate. According to data collected by the Department for Transport, Q1 of 2021 saw 73 per cent more battery electric vehicle (BEV) registrations than Q1 of 2020. With uptake ever increasing, automakers must address barriers to widespread adoption.

WHAT CHALLENGES DO WE FACE?

An extensive charging infrastructure across the UK will be needed to enable road transport’s decarbonisation, to meet consumer demand and to make EVs a viable option in all parts of the country. 

According to Zap Map, as of 21 July 2021, just under a third of all charging points were in Greater London, with more sparsely populated areas such as Northern Ireland accounting for just 1.3 per cent of all charging points. It is vital to tackle this disparity and ensure access to charging points is the same regardless of location to encourage EV uptake in rural communities.

HOW CAN TRANSPORT MANUFACTURERS SUPPORT THIS PLAN?

To support these goals, ensure compliance with fossil fuel bans and overcome these challenges, manufacturers must design vehicles and their components to facilitate decarbonised transport uptake.

EV2 modular resistor for electric vehicles

Cressall’s EV2 resistor is designed with the challenges of manufacturing EVs in mind. The EV2 is a dynamic braking resistor (DBR), which is an essential component of an EV. A DBR safeguards an EV’s power system by removing excess energy generated while braking. If the battery isn’t fully charged, this energy would be used to recharge the battery. However, when the battery is full or there is a failure, it’s vital to remove this excess energy from the system to prevent damage. A DBR dissipates it as heat, which can be used to warm the vehicle’s cabin or preheat the batteries too in order to achieve maximum efficiency.

The EV2’s flexible design makes it suited to every EV application. Its modular design means that up to five units can be combined in a single assembly to achieve a power rating between one kilowatt (kW) and 125 kW. Its extensive design range works up to 1500 Volts terminal to terminal and a resistance of up to 20 ohms (Ω) per single module. This flexibility means the resistor can be adapted to suit any automotive application — from small cars to large HGVs.

The government’s plan to decarbonise all domestic transport by 2050 will slash the sector’s contribution to total carbon emissions. With manufacturers’ support, this goal is achievable, accelerating the nation’s progress to net zero, reducing pollution and alleviating the damaging effects of climate change.

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ELECTRIFYING THE UK HEAVY VEHICLE MARKET

ELECTRIFYING THE UK HEAVY VEHICLE MARKET

The Department for Transport Statistics reports that there were 485,900 heavy goods vehicles (HGVs) licenced in the UK in 2020, but only 400 of these were battery electric powered. With HGVs being a significant contributor of carbon emissions, will we see an increase in electric power?

HGVs account for around 17 per cent of greenhouse gas emissions while contributing to just five per cent of vehicle miles. Switching from diesel or petrol to electric power reduces the tailpipe emissions of vehicles, while also providing performance benefits. However, electric HGVs remain in the early stages. For electric heavy vehicles to become commonplace, there is a need for further development of the technology.

BATTERY ELECTRIC VERSUS HYDROGEN FUEL CELL

A challenge of electrifying heavy vehicles is finding an energy storage solution that doesn’t add too much weight, which would increase energy consumption. Batteries must also possess a long range, allowing long distance freight. The main contenders for reducing vehicle emissions are battery electric and hydrogen fuel cell electric. Battery Electric Vehicles (BEVs) use chemical energy that is stored in rechargeable battery packs and use electric motors for propulsion.

However, the range between charges is limited, making it not so suitable for HGVs travelling a few hundred miles a day. This is exacerbated by the lengthy charge time of BEVs, extending to many hours for heavy vehicles depending on the charger.

Fuel Cell Electric Vehicles (FCEVs) also use an electric motor for propulsion but with a much smaller battery pack, with the fuel cell constantly converting the hydrogen to electricity, which only emits water from the tailpipe. FCEVs typically have a longer range and shorter fill time than BEVs, making them a stronger candidate for long-distance vehicles. Furthermore, the fuel cells can be stacked together to scale up power for a heavy vehicle. Fuel cells are more compact and lightweight than electric batteries, and most of the fuel cell can be recycled at end of life.

However, the majority of hydrogen currently being produced is made using fossil fuels through steam reforming, meaning hydrogen power is not emission free when its whole lifecycle is considered. If developments are made that allow more hydrogen to be produced from renewable resources, then FCEVs can become a more environmentally friendly option.

PERFORMANCE, RELIABILITY AND SAFETY

Electric vehicles (EVs) are generally more reliable than Internal Combustion Engine (ICE) vehicles as they consist of fewer moving parts, reducing the risk of breakdowns and the need for frequent servicing. Electric motors can deliver torque quickly with almost instant acceleration, making vehicles quicker to start. This is particularly beneficial for heavy vehicles that are carrying large loads on fast motorways or on an inclined gradient.

Heavy vehicles brake differently to cars, as they do not purely rely on their service brakes to slow down. Instead, they also use auxiliary and endurance braking systems, which don’t overheat as quickly on long declines and reduce the risk of brake fade or failure of the service brakes. In electric heavy vehicles, this braking is regenerative, which minimises wear on the service brakes and adds charge and range to the battery packs.

However, if there is a failure in the system, or the battery pack’s state of charge is unable to accept the charge, this could become dangerous. Using a dynamic braking resistor will dissipate the excess energy as heat to improve the safety of the braking system. Regenerative braking aided by braking resistors can also boost heating efficiency by feeding the dissipated energy back into the vehicle to heat the internal cabin. The resistor needs to be compact and meet the current ECE R13 Type –IIA endurance braking performance test. To pass this test, the resistor must allow the heavy vehicle to travel 6km at 30kph on a seven per cent decline with the endurance braking system active and without the service brakes overheating and failing.

FUTURE UPTAKE

Currently, the UK has banned the sale of petrol, diesel and hybrid cars from 2035 onwards. However, there have been talks on proposing a ban on diesel heavy goods vehicles by 2040 in order to remove all carbon emissions from freight transportation by 2050. The race for electrifying heavy vehicles is on, and there could be penalties in the future for those who do not use electric.

With only 400 battery electric heavy vehicles in the UK in 2020, electrifying the heavy vehicle market is in its early stages. However, with potential diesel bans looming, we must power ahead into an electric HGV future.

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