Fuel cell versus battery trucks

FUEL CELL VERSUS BATTERY TRUCKS

HOW CAN AUTOMOTIVE MANUFACTURERS CREATE A ZERO EMISSION FUTURE?

By 2040, all new heavy goods vehicles (HGVs) sold in the UK must be zero-emission. Advances in green energy technology mean this is possible, but automotive manufacturers are still in disagreement about what type of power source is best. In this article, Simone Bruckner, managing director of resistor manufacturer Cressall, explains the pros and cons of fuel cells and battery power, and what these mean for electrifying HGVs.

There are two main types of electric vehicle, categorised by their power source. Battery Electric Vehicles (BEVs) rely on a lithium-ion battery for power. Fuel Cell Electric Vehicles (FCEVs) on the other hand use a fuel cell, which combines hydrogen gas with oxygen to generate electricity.

HYDROGEN POWER

Hydrogen is the most abundant element in existence, so future supply is not an issue. Hydrogen power also has a much higher energy density than batteries, at around 35,000 watts per kilogram of hydrogen, while lithium-ion batteries only have around 200 watts per kilogram.

This increased energy density allows FCEVs to travel distances comparable to petrol or diesel vehicles, and up to 100 miles further than BEVs. For HGVs in particular, it also means that much heavier payloads are possible, with the ability to carry an extra two tonnes or more depending on the vehicle.

The main problem with hydrogen fuel remains with its production. Similar to the way we often refer to more environmentally friendly processes as “green”, hydrogen is colour-coded based on its method of production. Most of the hydrogen produced currently is defined as “grey”.

Grey hydrogen is generated using methane from natural gas, producing about ten times more carbon dioxide than hydrogen. Recapturing the carbon dioxide produced is possible, but it’s still not a perfect solution, only being able to capture up to 80 per cent of the generated carbon.

The ideal type of hydrogen is green, produced by separating hydrogen and oxygen molecules in water using electricity. Provided that the source of this electricity is renewable, this is the most environmentally friendly form of hydrogen. At present, the cost of production is the main barrier for this method, though it is expected to fall to a level that’s more competitive with grey hydrogen by 2035.

REFUELLING AND RECHARGING

Refuelling remains a hot topic for FCEVs. In terms of refuelling time, FCEVs have a huge advantage over BEVs, taking around three to five minutes to refuel. This means that lorries can get straight back onto the road with minimal downtime, without hampering delivery expectations.

In contrast, BEVs can take anywhere between 30 minutes to ten hours to recharge, depending on the voltage of the charger and the battery size. Considering the battery size required to power a HGV compared to a passenger car, it’s likely that most HGV charging times will sit on the higher end of the spectrum on a standard charger.

Rapid chargers operating at a higher voltage can be installed at HGV depots instead, giving access to much faster recharging times, though they will still not be as quick as FCEVS to refuel. It’s important to note, however, that UK legislation requires drivers to take regular breaks regardless.

By law, drivers should take a 45-minute break for every four and a half hours driving, and drive for a maximum of ten hours per day. Factoring in these numbers, the slower refuelling time of a BEV may not be as much of an issue as once thought, provided it can refuel sufficiently to reach the next point in its journey.

The abundance of charging points means that a BEV is never too far away from a top up. In contrast, there are only around 15 stations in the UK currently providing hydrogen fuel. Choosing FCEVs right now, therefore, means that careful route planning is required to ensure the lorry can safely reach a station.

Encouragingly, investments are being made in this area. Bosch has committed to set up 4,000 hydrogen fuelling points worldwide by 2030, and as the cut-off deadline looms for new petrol and diesel vehicles, it’s likely that similar schemes will follow.
The problems with lithium power
Most BEVs are powered by lithium-ion batteries. These have decreased substantially in price since they first started appearing in electric vehicles, making electric lorry fleets a lot more financially viable.

However, this downward pricing trend is not expected to last. High global demand of lithium is predicted to result in chronic shortages by 2030. While there is still enough lithium in the ground, lacking infrastructure means that not enough of it can be mined to meet modern demands for much longer.

Another issue with BEVs is their heavy reliance on the power grid, as more than half of the energy on the grid is provided by non-renewable sources. Grid reliance can also be tricky in the cases of power cuts and blackouts. Overnight power disruption may result in a half-empty battery the next day, having a knock-on effect to scheduled deliveries and supply chains.

PRESERVING BATTERY LIFE

In response to these issues, manufacturers should be looking for ways to ensure that their HGVs can get the maximum value out of their fuel. Preserving battery life can help to ease the pressure on the lithium supply, as well as lower overall fuel demand.

One of the ways that battery life preservation can be achieved is through regenerative braking. In an electric vehicle, the electric motor runs in two directions. The forward direction drives the movement of the wheels and the vehicle. Reversing the motor direction takes the excess energy away from the braking system and puts it back into the battery. Using regenerative braking, the kinetic energy from braking that would otherwise be wasted can be saved and reused elsewhere.

Batteries only have a limited capacity though, and a full battery has nowhere for the excess electricity to go. This can lead to component damage as well as overheating. To dissipate the excess electricity safely and prevent this from happening, a dynamic braking resistor, or DBR, can be used.

DBRs are also useful in ensuring that emergency braking can be done safely, which is essential in heavier vehicles. FCEVs struggle with fast acceleration and deceleration, as fuel cell output is not consistent due to the method of generating electricity. The solution is to install cells that have a higher output than what is needed, meaning that there is always sufficient energy available, and using the DBR to safely remove the excess.

Choosing a lightweight DBR like Cressall’s EV2 helps to reduce the overall weight of a HGV, maximising its payloads. The EV2 also has a modular design, allowing multiple modules to be combined to give up to 125 kW in one single unit, which could be then put in parallel or series with others for higher power for safe emergency braking. And at only a tenth of the size of conventional convection cooled DBRs, the liquid cooled EV2 provides a compact solution to safer braking.

It’s clear that there’s still a long way to go to providing cost-effective and sustainable fuel for heavy vehicles. But boosting battery life can go a long way in meeting overall demand. By implementing technologies like regenerative braking, even the largest of road vehicles can benefit from cleaner, greener fuel technologies.

CR526

Could hydrogen decarbonise transport?

THE HYDROGEN FUTURE OF EUROPE’S AUTOMOTIVE MARKET

April 2021 saw the latest collaboration in support of fuel cell electric vehicle (FCEV) uptake, with automotive manufacturer Nikola announcing plans to create a hydrogen pipeline and refuelling system across Europe. What technology is required to make hydrogen a viable option both in terms of sustainability and automotive efficiency?

Europe has one of the world’s most developed hydrogen markets and is home to over half of all projects, according to The Hydrogen Council and McKinsey’s Hydrogen Insights Reports 2021. Both the UK and the EU have plans to develop their hydrogen offering and have committed to reach a production capacity of five gigawatts (GW) and 40 GW respectively by 2030.

Despite the maturity of the sector, Europe’s hydrogen still needs considerable development in order to reach net zero targets and to become a viable fuel source for automotive applications. Making usable, renewable hydrogen is no easy feat — so where’s the best starting point?

CLEAN IS GREEN

First, we must consider how we make hydrogen green. Hydrogen can be produced in many ways, each corresponding to a different colour. Most hydrogen produced in Europe is currently grey — it is produced by mixing natural gas and steam to create hydrogen and carbon dioxide in a process known as steam methane reformation.

The problem with this production method is that it relies on a fossil fuel to produce hydrogen, which conflicts with hydrogen’s alleged sustainability superiority over petrol and diesel-powered vehicles.

Ideally, we need to make green hydrogen, which uses renewable electricity to separate the hydrogen and oxygen atoms that make up water in a process called electrolysis. This results in zero carbon emissions.

Geographically, Europe is in an advantageous position thanks to an abundance of renewable energy sources in the surrounding area. The EU’s Hydrogen Strategy Report has already identified North Africa as a priority region for increasing hydrogen availability across Europe, thanks to a plentiful supply of sunlight and subsequent renewable energy.

IMPROVING FUEL EFFICIENCY

Next on the agenda is making hydrogen-powered vehicles commercially viable. According to Hydrogen Mobility Europe, if hydrogen remains at the current low levels of demand, the cost of producing and supplying hydrogen could be passed onto end users. This would mean that hydrogen vehicles would cost more to run than both battery electric vehicles (BEVs) and fossil-fuelled cars. Therefore, any technology that can drive down cost is crucial to increasing uptake.

Fuel cell electric vehicles constantly convert hydrogen into electricity, which in turn charges the vehicle’s battery. In a process known as regenerative braking, most excess energy can be retained to help power the vehicle. However, if the battery is already fully charged or there is a failure in the system, there must be a mechanism in place to dissipate this energy surplus.

A dynamic braking resistor (DBR) is one of the most efficient ways to safely dissipate excess energy and ensure the system remains operational. Cressall’s EV2 DBR is a water-cooled resistor, which allows for safe dissipation without the need for extra components, resulting in an 80 per cent weight reduction when compared to a conventional air-cooled DBR.

These weight-saving properties lighten the load of the vehicle itself, meaning that it can travel further on the same amount of energy. This is particularly advantageous for weight-sensitive freight vehicles, such as pulp and paper or iron and steel transport. What’s more, the weight of a BEV’s battery or the additional components of an air-cooled DBR would reduce the potential load of the vehicle more than a FCEV would, which makes the EV2 and hydrogen a perfect combination for freight transport.

Nikola’s European hydrogen pipeline and fuel system is a landmark step in facilitating widespread uptake of FCEVs. However, if FCEVs are to overtake BEVs, then the refuelling system has to be accompanied by further developments in vehicle efficiency and hydrogen production to make the resource a completely sustainable, feasible option.

CRE471

Power Control Chopper

POWER PROVE LAUNCHES POWER CONTROL CHOPPER FOR CRITICAL TESTING

In response to growing demand for more precise power dissipation, load bank manufacturer Power Prove has launched a dedicated IGBT-based electronic power control chopper, for continuous regulation of its load bank product offering. The power control chopper can be easily integrated into load banks to achieve high power dissipation and a degree of precision superior to that offered by any competitor.

Power Prove, the load bank division Cressall Resistors, commissioned the design of the power control chopper to Italian Internet of Things (IoT) solution developer Techmakers. The combination of Power Prove’s in-depth knowledge of load banks and Techmakers’ expertise in electronic and software-controlled devices has resulted in a powerful, yet cost-effective, solution that meets the growing demands of the market.

A power control chopper is an electrically controlled solid state switch that is used to control the amount of current permitted to flow through a circuit. Normally, a high-power variable load requires multiple fixed value load sections ranging in values for power dissipation with contactors and a logic controller. However, by integrating the power control chopper into the system, a near-infinite set of values for power dissipation can be achieved using just a single resistor.

Power Prove’s chopper also has a closed-loop regulation circuit, which is capable of adapting to fluctuations in voltage and cold resistance variation without any input. Multiple units can be combined to reach high-power dissipation, enabling the load bank to withstand even the greatest of power values with high precision.

Anywhere that requires constant power, whether that’s a healthcare facility, manufacturing plant, or IT data centre, simply cannot afford a complete loss of power. These layers of infrastructure are often secured by an uninterruptible power supply (UPS) that provides power for critical operations if supply from the grid fails.

“The challenge for the managers these systems, which are often deployed as sources of back-up power in a black-out situation is how to determine whether the system is operational and will not fail on the relatively infrequent occasions when their use is required at a critical moment. Regular testing of emergency systems using load banks is therefore essential,” explained Andrew Keith, division director of Power Prove.

“Since these systems provide such a critical safety mechanism, a high level of precision is vital,” continued Keith. “The new power control chopper allows us to provide our load bank customers with a customisable load bank that can be easily integrated into an existing system to provide infinite levels of power adjustment at a degree of precision that is simply not available elsewhere on the market.”

An example of the power control chopper’s application is with battery discharge testing. The chopper can be used with a current feedback loop to provide a genuine constant current load on battery systems up to 1000 V DC. Multiple chopper units can be fitted inside the same load bank, or a combination of traditional fixed loads and chopper modules can be used to create a load bank with the current discharge capacity to suit its application.

In addition, the increasing adoption of electrical vehicles powered by batteries and fuel cells is generating a wide range of operating scenarios that need to be simulated. The development of the power electronic control module allows Power Prove to produce load banks that simulate a much more diverse range of operating conditions for research and development (R&D) testing, system commissioning tests and regular planned maintenance load testing.

The power control chopper is available globally from Power Prove, for more information, visit the website.

CRE460

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.

CR474