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.

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Diving into marine resistor design

DIVING INTO MARINE RESISTOR DESIGN

DESIGN CONSIDERATIONS FOR OFFSHORE ELECTRICAL COMPONENTS

Covering over 70 per cent of the Earth’s surface, the oceans are a vital element of our planet’s ecosystem. However, for the millions of vessels that cross them, the aquatic environment can present a problem. Vessels are increasingly using electrical systems to power across oceans, but a component’s design must account for these extreme conditions.

Whether for main propulsion propellors, crane or lifting systems, or cable laying, electrical drives can be found at the heart of many marine operations, offering increased control, reliability and mechanical simplicity. Dynamic braking resistors (DBRs) are an essential part of an electric drive system that remove excess energy from the system when braking to either dissipate as heat if system is not receptive to regeneration or if system is receptive, but energy level goes beyond the system limits, so needs to be removed.

When designing electrical components for offshore applications, material selection is key from the start of the process to guarantee that equipment will perform under harsh conditions, including saline atmosphere, high wind loadings and corrosive sea water.

Engineers tasked with designing resistors for marine applications must consider material choice, structural stability and cooling method.

CORROSION-RESISTANT MATERIALS

Sea water and the saline atmosphere is corrosive, which could leave equipment inoperable. Due to this, stainless steel, combined with special paint systems, is typically used for the enclosure metalwork for resistor elements. With materials containing at least 10.5 per cent chromium, stainless steel reacts with oxygen in the air to produce a protective layer on its surface to prevent corrosion if not painted.

There are many grades of stainless steel that can offer high corrosion resistance, which can be further enhanced by the addition of extra elements. For below-deck applications, 316 and 304 stainless steel contain nickel to broaden the protective layer created by the chromium, and can be used in unpainted condition.

However, for above-deck components, 316 stainless steel has a higher nickel quantity and added molybdenum, so the resistor unit’s metalwork receives optimum protection against the marine atmosphere, but in some conditions, painting will also be required. Cressall’s resistor enclosures for the EV2 resistor terminal cover boast at least an IP56 ingress protection rating, certifying that sea water cannot enter the unit to cause harm.

In addition to the exterior, it is important that the resistor’s element can withstand the harsh conditions. For these applications, Alloy 825 sheathed mineral-insulated elements are less vulnerable to atmospheric corrosion. As the element in encased within the mineral insulated sheathing, the sheath is at earth potential, so if water or high humidity is present this will prevent accidental contact with the live element, making them a much safer choice for marine applications.

STRUCTURAL STABILITY

Weather at sea is unpredictable, so vessels must be able to withstand the large variance in wind and harsh sea conditions found worldwide. Many offshore structures such as wind turbines are located in areas with high winds, so if the system requires resistors to help provide stability to their electrical components these considerations must be considered within a resistor’s design.

Considering the impact of a vessel’s rotational motions — its side-to-side motion, or pitch, and its front-to-back motion, or roll, is crucial. Design engineers need to ensure that there is enough mechanical support in the structure to stabilise the resistors for safe operation when it is subjected to these forces.

Cressall can conduct finite element analysis (FEA) to help ensure structural stability. FEA allows design engineers to predict a product’s performance in the real world, then see the impact of forces and make changes accordingly. This ensures the resistor performs well in the potentially extreme weather conditions.

It’s also important to consider the size constraints of marine applications. In contrast to onshore units, offshore electrical components must fit into a compact area, so the size of the unit’s support structures must be minimised without compromising durability.

COOLING METHOD

An essential part of a resistor is its cooling system. Since the resistor dissipates excess energy as heat, the cooling system is responsible for cooling the resistor element to ensure continued operation. Depending on the layout and resources of the system, resistors can be naturally or forced air or water-cooled.

Air-cooled resistors come in two types — forced and naturally cooled systems. Forced cooling systems use a fan to dissipate heat in a compact space. These units are suitable for deck mounting and can be secured using anti-vibration mounts. Natural cooling is the most common in marine applications, offering a higher power rating and can be mounted in machinery spaces, protected environments or on deck. For machinery spaces or protected areas, consideration should be given to how the hot air released from the resistors should be evacuated to ensure other equipment mounted locally does not overheat.

Alternatively, the cooling system can use the vessel’s chilled water system, which circulates cool water for air conditioning and equipment cooling. If the chilled system uses sea water, titanium-sheathed elements with super duplex steel metalwork can be incorporated, for continuous use in acidic, tropical sea water and downgraded to 316 stainless steel for freshwater systems.

The ocean is a valuable asset for energy, transport and trade. Ongoing development of electric drives for marine applications can be challenging, but taking these conditions and energy savings into account makes them a viable and advantageous option for powering vessel and for use in offshore structures.

When required Cressall can design the resistors to help with your application. Contact us here.

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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.

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Breaking the ice

THE ROLE OF RESISTORS IN POWERING ICEBREAKERS

Sea ice covers around twelve per cent of the world’s oceans, blocking the path for ships attempting to travel across the Earth’s coldest regions. Although they aren’t a new concept, icebreaker ships consistently play a crucial role in clearing these routes for trade, research projects and travel.


Icebreaker ships are a special class of vessel designed to break through even the thickest of ice sheets. Initially developed to open up trade routes that experience either seasonal or permanent ice conditions, ice breakers are commonly found in areas like the Barents Sea, Artic Ocean and the Saint Lawrence Seaway. More recently, they’ve also been used to support scientific research projects in the Arctic and Antarctic.

DETAILED DESIGN

To meet the challenges of ice-covered waters, icebreaker ships have a very specific, carefully considered design. The bow of an icebreaker has a unique shape that is smoother and rounder than a standard vessel, to allow it to easily glide over thick ice sheets with minimal opposing force. As it glides over the ice in this way, the weight of the ship descends onto the ice, crushing it and clearing the path.

To power the icebreakers to smoothly move over this difficult seascape, the vessels also require a significantly enhanced electric propulsion system that matches the power requirements for the icebreaker’s thrusters to break through the ice. 

As the sole enabler of transportation through these ice-covered waters, it’s essential that the propulsion system — and all of the components that it includes — are reliable, effective and safeguarded. If an icebreaker were to fail in transit, there could be major disruption to the global supply chain in the repair time. Think the Suez Canal fiasco in 2021, but much colder.

RELIABLE RESISTORS

One component that plays a crucial role in ensuring the safe operation of an icebreaker’s electric propulsion system is a dynamic braking resistor (DBR). When there is no ice in the vessel’s path, there’s less load on the system, meaning that any excess energy produced is surplus to requirements. To dissipate this excess energy, a DBR is integrated into the system, which acts as a load dump during propulsion and icebreaking activities. This load dump activity stabilises the power system, giving a constant load to the vessel’s gas engines.

It’s important to include a DBR in the electric drive system of an icebreaker for several reasons. Without the DBR, the power system would destabilise, risking potential damage to other components of the power circuit. If this continued, it could eventually lead to the loss of the vessel’s icebreaking function and complete failure of the power system.

Therefore, integrating a DBR is an absolute essential for icebreaker vessel design engineers. However, it’s not as simple as just selecting a DBR. There are several design elements for this specific application that must be considered to ensure the drive’s optimal performance.

MARINE MATTERS

When designing electrical components, like resistors, for use on icebreakers, there are several application-specific factors to consider. Each component needs to be able to withstand the salty, cold and unstable conditions that are common at sea. 

In terms of structural stability, conducting rigorous testing procedures like finite element analysis (FEA) provides evidence of a component’s ability to withstand unpredictable, inhospitable conditions. It’s also important to design in line with standards outlined by the global testing, inspection and certification specialists Bureau Veritas, for global compliance.

The saline atmosphere at sea is corrosive, so selecting the right material is essential to prevent salty sea water from leaving equipment inoperable. For metal components, it’s important to use stainless steel with a chromium content of at least 10.5 per cent. This enables the stainless steel to react with oxygen to produce a protective layer that prevent corrosion, even in an unpainted condition.

Icebreaker vessels are an indispensable part of the marine transport system. While their function is simple, having the right electrical components, including DBRs, designed specifically for icebreaking applications, is crucial to their safe and successful operation, making even the most treacherous of routes in the Polar regions accessible all year round.

Cressall designs and manufactures DBRs specifically for icebreaker vessels. Our team of expert engineers works together with our customers to develop the ideal, customer DBR solution for each application. For more information, please get in touch here.

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