Wales to Launch UK's First Hydrogen Highway, But Is Hydrogen Fuel the Way Forwards?

Hydrogen refulling points are set to appear across the M4 in Wales, UK.

As the world looks more and more to alternative energy sources and low carbon alternatives to fossil fuels, new terms such as Hydrogen vehicle and hydrogen fuel cell are being tossed around. But what does this mean? How does hydrogen work as a fuel? Is it better than petrol? What is a hydrogen fuel cell, and why not just burn the gas? In this short piece, I will be looking at these questions and answering them in simple layman's terms.

Hydrogen as a source of energy:

The first thing you need to realise is that however you use it, Hydrogen is not a source of energy! It is what is known as an 'energy carrier'. Basically, Hydrogen can be used to 'trap' energy in a form that can be more easily transported. Petrol is actually a source of energy in and of itself- you simply extract it from crude oil by distillation, and when you burn it, energy is released. The reason why hydrogen fuel is not technically a source of energy is because it is not naturally occurring in nature- you can't just drill for it like oil, you need to manufacture it.

Hydrogen is very reactive, meaning that it quickly bonds with other chemicals, making it useless. It's a lot like sticking two Lego bricks together to make one big one- you no longer have the original bricks, you have one large structure. When hydrogen bonds with Oxygen, energy is released.

So, when you burn hydrogen, it joins with oxygen and in the process, releases energy. But because you need to spend energy to get the hydrogen by itself in the first place (Pulling apart the bricks), there's no net gain of energy. In fact, you loose a lot of energy when you compare the energy you get out of burning hydrogen compared to the energy cost of 'making' and transporting it.

So Why use Hydrogen as a fuel then?

Electricity is the main energy requirement to 'make' hydrogen. This means that in a out way, a Hydrogen powered car is effectively powered by electricity. Energy is 'trapped' by making hydrogen, then released when the hydrogen is burned- basically it acts like a carrier, transporting energy from electrical mains to your car engine. This means that hydrogen fuel is as 'green' as the source of the electricity used to manufacture it. For example, if you manufacture hydrogen using electricity from a coal fired power station, it will have a large carbon footprint, and probably be no better for the environment than simply burning petrol!

However, if you generate hydrogen from renewable or carbon free sources such as wind power, then the carbon footprint from the car will be much smaller.

This is the key to the push for hydrogen- a means for green power sources to power your car!

Does this mean that Hydrogen fuel will stop carbon Emissions?

Sadly not. As was indicated, Hydrogen fuel is only as green as the electricity used to produce it. This means that research into green electricity production is just as important as Hydrogen fuel for producing a low carbon economy. But the good news is that when hydrogen is burned it combines with oxygen to form something we are all familiar with- Water! this means no carbon, sulphur or any other chemicals will be in the car's exhaust- only pure water vapour.

What's the difference between a Hydrogen fuelled car and a petrol one?

There are two designs for Hydrogen cars. The first (and simplest) just burns the hydrogen directly, treating it exactly like petrol. A small amount of hydrogen is injected into the engine cylinder, and it lit by a spark plug. As it explodes, it puts pressure on the piston, forcing it to move and driving the whole system.

The second design uses a wonderful piece of equipment called a Hydrogen fuel cell. The Fuel cell works by breaking up the Hydrogen and Oxygen into charged ions (Other chemicals can also be used depending on the design of the cell). This means there is an imbalanced charge across the cell, forcing electrons to flow through a conductor to try and balance out the difference. The movement of electrons is the very definition of an electric current, hence the fuel cell produces a current.

Fuel cell cars would effectively behave like electric cars- quiet, smooth operation, even though they would still need to be 'filled up' at the pump.

In both cases, the end product is water.

What are the problems facing hydrogen fuel projects?

The main issues are those of cost and efficiency. It takes a lot of time and effort to produce hydrogen, and the element itself will only trap a small portion of the energy required to make it. This means you are spending a lot of money, and wasting a lot of energy compared to the energy you get back from the hydrogen.

That said, many industries produce 'waste' hydrogen (such as cracking at petro-chemical plants), and this provides a cheaper source of hydrogen fuel. In fact, Italy is looking at using this to create the world's first large scale hydrogen power plant.

Hydrogen fuel cells have problems all of their own. Currently they have a very short lifespan compared to the mechanical components of a car, and they don't produce as much power as the batteries for a standard electric car. However, the technology is advancing and hydrogen fuel cells are becoming more and more powerful and reliable as research progresses.

Distribution is also a major concern- every refuelling station in the country would need to be refitted with hydrogen pumps as hydrogen is a gas, meaning ti must be treated differently. The cost of this would be huge, meaning most governments are very sceptical of the cost- especially considering the other drawbacks of Hydrogen fuel.

So are Fuel Cells and Hydrogen the way of the future?

It's hard to call. In my opinion, probably not. Hydrogen fuel will probably find a niche among smaller vehicles such as model aircraft, UAVs and submersibles, but for commercial aircraft and cars, hydrocarbons remain the king! But that doesn't mean we can afford to keep using petrol, even as technologies such hybrid cars and energy recovering brakes become more common- petrol is a finite resource. So perhaps the question we should be asking isn't if hydrogen fuel is the way forwards, but if it isn't- what is?

Hopefully, you've now got a better idea of the role of Hydrogen fuel and fuel cells in the future. If you have an interested in this topic, then please remember to look into it further.