A guide to understanding hydrogen-powered technology

What happens under the bonnet of a hydrogen vehicle? Although many people use the term “hydrogen engine”, in reality, hydrogen vehicles use electric engines powered by hydrogen. Hydrogen trucks, cars, tractors and so on are indeed electric vehicles or more precisely Fuel Cell Electric Vehicles (FCEV).

However, unlike the “conventional” electric vehicle (which should really be referred to as a battery electric vehicle or BEV) – whose electricity is stored in the battery during charging – the “hydrogen electric vehicle” generates its own electricity using a hydrogen fuel cell.

To use a hydrogen vehicle, the user must fill the hydrogen tank rather than recharging the battery.

There are two types of hydrogen engine technology:

• The FCEV: an electric vehicle with an electric engine powered by a fuel cell – most hydrogen vehicles available today use this technology,
• The ICE: A vehicle with a hydrogen internal combustion engine. This technology, which is not yet on the market, is in the R&D phase and interests manufacturers such as Toyota, Porche, and MAN. This type of engine would keep much of the current engine’s operating system the same and would require minimum adjustments to vehicles.

What defines the power of a hydrogen engine?

FCEVs have several design parameters that define a vehicle’s power:

• Battery capacity (in kWh)
• Fuel cell power (in kW)
• Hydrogen storage capacity (in kg)
• Overall engine power in (kW)
  

Depending on the vehicle’s purpose, manufacturers design various configurations of these four elements.

Gas or liquid hydrogen?

These are the two means of storing hydrogen and each has its advantages and disadvantages, depending on the vehicle’s purpose. Liquid hydrogen allows you to store four times more hydrogen but liquefying hydrogen results in a lower energy yield due to the additional liquefaction operation. What’s more, once it is in the car, it must be used very quickly before it turns back into gas and expands. This means it must be used or evacuated ... and lost!

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How exactly does a fuel cell work?

There are several types of fuel cells, which convert fuel into energy. The most common is the hydrogen fuel cell, which converts hydrogen (the fuel) into electricity (the energy), through the electrochemical reaction of hydrogen and oxygen.
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This process, which occurs instantaneously, powers the electric engine while releasing only water.

Technically, the fuel cell uses a “redox” reaction to produce electricity. It comprises two electrodes: an oxidising anode (emitting electrons) and a reducing cathode (collecting electrons), separated by an electrolyte, which directly conducts the ions from one electrode to the other and blocks the electrons, forcing them to pass through the external circuit of the battery.

The tank continuously supplies the anode with hydrogen, while the cathode receives oxygen (from the air).

The anode causes the fuel to oxidise and release electrons, which are forced by the ion-charged electrolyte (which separates the two electrodes) to pass through an external circuit. This external circuit therefore provides a continuous electric current which powers the engine.

Once reunited in the cathode, the ions and electrons recombine with oxygen. This combination causes reduction, which – in addition to the electric current – generates heat and pure water vapour, which escapes in the form of gas through a small tube placed under the vehicle, either while driving or by pressing a button at the end of the trip.

• The tank continuously supplies the anode with hydrogen, while the cathode receives oxygen (from the air).
• The anode causes the fuel to oxidise and release electrons, which are forced by the ion-charged electrolyte (which separates the two electrodes) to pass through an external circuit. This external circuit therefore provides a continuous electric current which powers the engine.
• Once reunited in the cathode, the ions and electrons recombine with oxygen. This combination causes reduction, which – in addition to the electric current – generates heat and pure water vapour, which escapes in the form of gas through a small tube placed under the vehicle, either while driving or by pressing a button at the end of the trip.

Running a hydrogen engine therefore emits only pure water and is completely clean, provided that a completely clean hydrogen fuel is used.

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Hydrogen fuel cell cars represent a promising alternative to traditional combustion engine vehicles and battery electric vehicles, as they combine the best of both worlds: long driving range and quick refueling, while producing zero harmful emissions. In this article, we'll explore how hydrogen cars work, their components, benefits, and challenges, as well as the future of this innovative technology.

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The Basics of Hydrogen Fuel Cell Cars

Hydrogen fuel cell cars are electric vehicles that generate electricity by converting hydrogen gas into electrical energy through a chemical reaction in a device called a fuel cell. This electricity powers the electric motor, which drives the car. The only byproduct of this reaction is water vapor, making hydrogen cars an environmentally friendly transportation option.

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Types of Fuel Cells in Hydrogen Cars

There are several types of fuel cells, but the most common ones used in hydrogen cars are:

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PEM Fuel Cells

Proton Exchange Membrane (PEM) fuel cells are the most common type of fuel cell used in passenger cars. They operate at relatively low temperatures (around 80°C), making them suitable for quick start-up times and providing a high power density, which is essential for vehicle applications.

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Alkaline Fuel Cells

Alkaline fuel cells (AFCs) use an alkaline electrolyte and are known for their high efficiency. However, they are more sensitive to impurities in the hydrogen fuel and less common in automotive applications.

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Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) operate at much higher temperatures (800-1000°C) and are typically used in stationary power generation applications. Their use in vehicles is limited due to their slow start-up times and the need for significant thermal management.

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Components of a Hydrogen Fuel Cell Car

Hydrogen fuel cell cars consist of several main components:

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Fuel Cell Stack

The fuel cell stack is the heart of the hydrogen car, where hydrogen and oxygen react to produce electricity, water, and heat. The stack is made up of multiple individual fuel cells connected in series.

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Hydrogen Storage

Hydrogen is stored in high-pressure tanks, usually at 350 or 700 bar, to provide sufficient energy for driving long distances. These tanks are made from advanced materials to ensure safety and durability.

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Electric Motor

The electric motor converts the electrical energy generated by the fuel cell stack into mechanical energy, which drives the car. Electric motors in hydrogen cars are similar to those used in battery electric vehicles and are known for their high efficiency and instant torque delivery.

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Power Electronics

The power electronics in a hydrogen car control the flow of electricity between the fuel cell stack, the electric motor, and other components. They also manage the energy generated during regenerative braking and provide protection against electrical faults.

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Battery

A small battery or supercapacitor is used in hydrogen fuel cell cars to store energy from regenerative braking and provide additional power during acceleration or high-load situations. This battery is much smaller than the ones used in battery electric vehicles.

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How Hydrogen is Produced for Fuel Cell Cars

Hydrogen can be produced through various methods, including natural gas reforming, electrolysis of water, and biomass gasification. The most common method for producing hydrogen is steam methane reforming, which uses natural gas as the primary feedstock. However, this process generates carbon dioxide emissions. The greenest method for hydrogen production is electrolysis, which splits water into hydrogen and oxygen using electricity from renewable sources like solar or wind energy.

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The Process of Generating Electricity in a Hydrogen Car

When hydrogen fuel is supplied to the fuel cell stack, it is combined with oxygen from the air. In a PEM fuel cell, hydrogen molecules pass through a catalyst, which splits them into protons and electrons. The protons then move through a proton exchange membrane, while the electrons are forced to travel through an external circuit, generating electricity. The protons and electrons recombine with oxygen on the other side of the membrane to produce water as the only byproduct.

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Benefits of Hydrogen Fuel Cell Cars

Hydrogen fuel cell cars offer several advantages over conventional vehicles and battery electric vehicles:

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Zero Emissions

Hydrogen cars emit only water vapor, making them an environmentally friendly transportation option that can help reduce greenhouse gas emissions and improve air quality.

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Quick Refueling

Refueling a hydrogen car takes only a few minutes, similar to filling up a gasoline-powered vehicle, as opposed to the longer charging times required for battery electric vehicles.

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Longer Range

Hydrogen fuel cell cars can achieve a driving range of 300 to 400 miles (or more) on a single tank, making them more suitable for long-distance travel compared to most battery electric vehicles.

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Challenges Facing Hydrogen Fuel Cell Cars

Despite their advantages, hydrogen fuel cell cars face several challenges:

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Infrastructure

The hydrogen refueling infrastructure is limited, with only a few hundred stations worldwide. Expanding the network of hydrogen refueling stations will be crucial for the widespread adoption of hydrogen cars.

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Cost

The cost of hydrogen fuel cell cars is still relatively high due to the expensive materials and complex manufacturing processes involved. However, advances in technology and economies of scale could help reduce costs in the future.

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Energy Efficiency

The overall energy efficiency of hydrogen fuel cell cars is lower than that of battery electric vehicles due to energy losses during hydrogen production, storage, and conversion to electricity in the fuel cell.

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Hydrogen Fuel Cell Car Brands and Models

Several automotive manufacturers have developed and released hydrogen fuel cell vehicles, including Toyota (Mirai), Honda (Clarity Fuel Cell), Hyundai (Nexo), and Mercedes-Benz (GLC F-CELL).

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The Future of Hydrogen Fuel Cell Cars

The future of hydrogen fuel cell cars will depend on the development of cost-effective and sustainable hydrogen production methods, advances in fuel cell technology, and the expansion of the hydrogen refueling infrastructure. As these challenges are addressed, hydrogen cars could play a significant role in the transition to cleaner, more sustainable transportation.

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Conclusion

Hydrogen fuel cell cars offer a promising alternative to traditional combustion engine vehicles and battery electric vehicles, with benefits such as zero emissions, quick refueling, and longer range. However, challenges such as infrastructure, cost, and energy efficiency must be overcome to enable widespread adoption. As technology advances and the hydrogen refueling infrastructure expands, hydrogen fuel cell cars could become a vital part of our sustainable transportation future.

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As the world moves towards greener, more sustainable transportation options, hydrogen cars and electric cars have emerged as viable alternatives to traditional gasoline-powered vehicles. This article will delve into the workings of both hydrogen and electric cars, discussing their advantages and disadvantages, and exploring their potential impact on the environment and the future of transportation.

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How Hydrogen Cars Work

Hydrogen cars are powered by hydrogen fuel cells, which generate electricity through an electrochemical reaction between hydrogen and oxygen. The electricity produced is used to power an electric motor, which drives the car. The only byproduct of this process is water, making hydrogen cars a zero-emission vehicle.

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How Electric Cars Work

Electric cars are powered by rechargeable batteries that store electricity. These batteries provide power to an electric motor, which drives the car. Electric cars produce no tailpipe emissions, making them an environmentally friendly option.

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Advantages of Hydrogen Cars

1. Zero tailpipe emissions
2. Fast refueling times
3. Longer driving range compared to electric cars
4. Lighter weight due to smaller battery packs

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Advantages of Electric Cars

1. Zero tailpipe emissions
2. Lower operating costs due to fewer moving parts and lower energy costs
3. Quieter operation
4. Widespread charging infrastructure

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Disadvantages of Hydrogen Cars

1. Limited refueling infrastructure
2. Higher vehicle costs due to expensive fuel cell technology
3. Limited vehicle availability

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Disadvantages of Electric Cars

1. Longer charging times
2. Limited driving range compared to hydrogen cars
3. Heavy batteries can affect vehicle performance

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Environmental Impact

Both hydrogen and electric cars offer significant environmental benefits compared to traditional gasoline-powered vehicles. While electric cars have a smaller carbon footprint due to their reliance on electricity, hydrogen cars also contribute to a cleaner environment by producing only water as a byproduct.

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Charging and Refueling Infrastructure

While electric vehicle charging stations have become more prevalent, hydrogen refueling infrastructure remains limited. This could change in the future as more investments are made in hydrogen technology and infrastructure.

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Range and Performance

Hydrogen cars generally offer a longer driving range than electric cars, making them a more suitable option for long-distance travel. However, electric cars provide better acceleration and torque, leading to a more responsive driving experience.

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Car Availability and Pricing

As of now, electric cars are more widely available and affordable than hydrogen cars. This is due to the higher production costs associated with hydrogen fuel cell technology. However, as technology advances and economies of scale are achieved, hydrogen car prices could decrease.

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Government Incentives and Regulations

Governments worldwide are increasingly offering incentives and implementing regulations to encourage the adoption of hydrogen and electric cars. These incentives can include tax breaks, rebates, and other financial benefits, making the transition to cleaner transportation more accessible.

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The Future of Hydrogen and Electric Cars

Both hydrogen and electric cars will play an essential role in the future of transportation as the world moves towards more sustainable options. While electric cars currently have the edge in terms of availability and infrastructure, hydrogen cars have the potential to become a more prominent player in the market as technology advances and infrastructure expands.

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Conclusion

Hydrogen cars and electric cars both offer viable alternatives to traditional gasoline-powered vehicles in the pursuit of more sustainable transportation. While electric cars currently enjoy greater availability, lower costs, and more established charging infrastructure, hydrogen cars have the advantage of longer driving ranges and faster refueling times. As technology progresses and infrastructure develops, the competition between hydrogen and electric cars will continue to evolve, ultimately benefiting consumers and the environment alike.

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