Singing a Rainbow – Unpicking the story of hydrogen

Introduction

In July 2021 we decided to buy a battery electric vehicle, commonly abbreviated to BEV, to replace our 10-year-old fossil fuel car in order to reduce our carbon footprint. We also went for solar panels at the same time.

In September 2021 ERA co-organised Milland Green Fair as part of the Great Big Green Week initiated by the Climate Coalition.

At Milland Green Fair we had our electric car on display, with another electric car, two electric bikes and an electric trike, together with the information I had researched prior to our car purchase on the lifetime carbon footprint of a BEV as compared to petrol, diesel and hybrid cars. Lifetime carbon footprint is defined the CO2 generated at manufacturing stage through to end of life, which includes fuel, servicing, repair, and end of life disposal. We concluded that a BEV was the way forward to meet our needs.

It was put to me that at the Green Fair that hydrogen powered cars would be the future replacement for fossil fuelled internal combustion engine vehicles (FFICEVs) of which sales of new cars and light vans will end by 2030, and by 2035 that ban will extend to hybrids as well. 

My immediate response to that comment was that the current widely used method of creating hydrogen using steam gasification requires a significant amount of energy in production. While in theory it creates less CO2, it still creates CO2 as well as creating particulate matter, oxides of nitrogen, which are harmful to our respiratory system, and methane which is harmful to the environment.

For this article I am going to discuss the pros and cons of hydrogen fuel generation, the current hydrogen fuel cells as used in cars, and the feasibility of hydrogen cars in term of opportunities and barriers to them becoming mainstream.

The rainbow colours of hydrogen generation 

Historically I have been familiar with are terms such as Blue Hydrogen if it’s made from the gasification of fossil fuels or Green if made by using renewable energy, however it is a bit more complex than that. So much research is going on in so many different areas of hydrogen generation and each one seems to be being given a different colour of the spectrum! Current terminology includes the following:

Brown or Black Hydrogen

In simple terms hydrogen is created by the gasification of fossil fuels such as coal or lignite. The process involves heating them to temperatures in excess 700deg C, without combustion and with the controlled introduction of oxygen and steam. This method still creates CO2 and other pollutants. 

Grey hydrogen: the most common

Most manufactured hydrogen nowadays comes from natural gas which also contains some carbon. This carbon and can be separated out via a process involving water, called ‘steam reforming’, but the excess carbon generates CO2. This hydrogen is called grey whenever the excess CO2 is not captured. Grey hydrogen accounts for most of the production today and emits about 9.3kg of CO2 per kg of hydrogen production. 

The production of brown or black hydrogen without CO2 capture creates significantly more CO2 that the production of grey hydrogen without CO2 capture.

Blue hydrogen: putting the emissions underground

Hydrogen is considered blue whenever the emission generated from the steam reforming process are captured and stored underground via industrial carbon capture and storage (CSS), so that it is not dispersed in the atmosphere. That is why blue hydrogen is often considered a carbon neutral energy source, even though ‘low carbon’ would be more accurate since around 10 to 20% of the generated CO2 currently cannot be captured.

Turquoise hydrogen: solid carbon as a by-product

A new way of extracting hydrogen from natural gas is currently in experimentation phase. The gas can be decomposed at very high temperatures generating hydrogen and solid carbon thanks to a process called methane pyrolysis. This hydrogen is then referred to as ‘turquoise’ or low carbon-hydrogen.

Pink, yellow, green hydrogen

If the hydrogen is produced by water electrolysis, that is using electricity to decompose water into hydrogen and oxygen, then we have a palette of three colours: pink, yellow and green. 

In this case, the full life-cycle emissions of this electricity-based hydrogen production, depends on how the electricity is generated.

Pink: from nuclear energy

The colour pink is often used for hydrogen obtained from electrolysis through nuclear energy.  

Yellow: using a mix of whatever is available

The colour yellow sometime indicates hydrogen produced via electrolysis through solar power, but often is also used to indicate that the electricity used for the electrolysis comes from mixed sources based on availability (from renewables to fossil fuels).

Green: from renewables

Last but not least comes green hydrogen, often also called ‘clean hydrogen’, produced using electricity generated from renewables and currently accounting for around 1% of the overall hydrogen production. The European Commission intends to change that and build an entire strategy to support hydrogen, highlighting its potential for a climate neutral Europe and putting it right at the centre of the EU Green Deal (and its conspicuous budget).

There are almost as many types of electrolyser technologies for green hydrogen as there are colours of hydrogen. Electrolysers ‘split water, by applying an electric current to it, they use different materials, set-ups and operational temperatures, resulting in individual strengths and weaknesses’ - see Davine Janssen from Euractiv.com who takes a thorough look at the different approaches in China and the EU.

Processes for hydrogen generation and hydrogen power/energy in vehicles

Click here for a summary of how hydrogen is produced and how it functions to produce electricity for fuel cell electric vehicles (FCEVs).

This link gives more information on how green hydrogen is and its future in reducing CO2, its resilience and economic challenges.

Benefits and disadvantages of hydrogen as a fuel for a FCEV

Benefits:

• Clean tailpipe emissions, water only

• Refuelling time similar to fossil fuel vehicle

• Potential for longer vehicle range than battery electric vehicles

• Lighter vehicles, BEVs, have heavy batteries

• Mechanically simple

Disadvantages:

• Electronically complex

• Currently only 11 refuelling stations UK 

• Currently technology is expensive, more so than BEV

• Fuels Cells are less energy efficient than BEVs - 15-30% of available energy in the fuel source is used to drive the vehicle compared to BEVs which is 70 to 90% of available energy

• Cleanliness in terms of CO2 depends on how hydrogen is produced

• Governments and manufacturers are currently focusing on developing the technology for haulage of goods (trucks, trains, ships etc.), buses, air passenger transport, and domestic boilers, not specifically for passenger cars

Materials/resources

With new technologies comes an increase in demand for rare materials for the electronics that function within these systems. 

According to the Society of Motor Manufactures and Traders current fossil fuelled vehicles use on average somewhere between 1500 and 3000 microchips to control vehicle systems depending on the specification of the vehicle, basic models at the lower end around 1500 and high-end luxury models around 3000 or more.

BEVs currently use a range of rare materials such as lithium and cobalt, FCEV (hydrogen fuelled) require platinum, nickel, zirconium plus other less rare materials. 

As I write this article vehicle manufactures are facing a shortage of microchips because of supply chain issues from the Far East, due mainly to Covid, which is negatively impacting on vehicle production. 

Also, it’s important to understand where the deposits of these rare materials are in the world and where in the world these materials are processed. Such resources give countries like Russia and China enormous power over consuming countries, which is another a topic for another time.

Summary

Individual personalised vehicle travel faces many challenges in the future such as requirements to reduce carbon footprints of manufacture and operation, vulnerabilities of supply of finite material resources, and the impact on the environmental and human cost of extracting and processing these resources.

We need to own less cars, use public transport more often and develop systems for car sharing.  We need to consume less, not only with regard to personal transport but also all of the technologies we use in our homes and personal life, all our ‘smart’ goods.  

We need to ‘live simply’ so our grandchildren can ‘simply live’.   

Sources of Information for and against the future of hydrogen for road transport

Energy Cities - 50 shades of (grey and blue and green) hydrogen

Student Energy - hydrogen generation and what is a fuel cell?

Car - are hydrogen fuel cells the future?

Autocar - why is hydrogen no longer the fuel of the future?

Wheels 24 – opinion: road transport should be rapidly decarbonised, but hydrogen is not the answer.

Tech Explore - advancing water electrolysis technology for the production of green energy.