Episode #2: Is hydrogen the silver bullet to global warming?

Dear Friends!

I was over the moon to see that my Net-Zero Academic newsletter was so well received by my LinkedIn family! At the time of writing, there's 4,448 of you who subscribed to my content. Before I move to the main content of this newsletter, I wanted to say thank you to each one of you! Your following gives me confidence and motivation to keep on sharing updates around net-zero transition and academic careers.

Net-zero transition

I've noted that there was quite a lot of discussion around hydrogen over the past couple of weeks. But is hydrogen the silver bullet to global warming? Will we see hydrogen-fuelled cars on our streets and will our homes be heated via hydrogen?

I don't think so.

Quoting Paul Martin, "I think it's a dumb thing to use as a fuel, or as a way to store electricity."

This is in line with the white paper by the International Council of Clean Transportation that confirms using hydrogen for heating may not be the most cost-effective to heat our homes. They state that on average, the households with a heat pump (~￡500/year) would be better of than those with hydrogen heating (~￡1100/year).

Why? Let's look at it from the thermodynamic point of view and assume that we use renewable energy as a primary source of energy. For the purpose of this article, I define energy efficiency as:

Energy efficiency = (Energy Output / Renewable Energy Input) x 100%

Hydrogen cases

For 100 kWh of renewable energy, we would obtain at most 75 kWh of hydrogen (25% loss). Transportation and storage of hydrogen would consume another ~8 kWh (11% loss), giving us the final hydrogen output of ~67 kWh.

Now if we use hydrogen in our cars, we would hydrogen back into electricity, usually at the efficiency of about 50%. This gives us about 33.5 kWh. But we need to account for the DC/AC (5% loss) and engine loss (10%). Consequently, the final amount of electricity delivered to the electric engine in your car would be 28 kWh, and that's out of 100 kWh of renewable energy produced. The energy efficiency of the overall process is 28%.

If we use hydrogen for domestic heating, we would convert hydrogen (150 MJ/kg) into heat. Let's assume a boiler efficiency of 90%. Our 67 kWh of hydrogen from renewables would be converted into ~60 kWh of heat, giving the overall energy efficiency of the process of 60%.

It seems reasonable, doesn't it? Here is what Kwasi Kwarteng, Secretary of State for Business, Energy and Industrial Strategy, said about hydrogen use.

"Hydrogen is one potential key option for decarbonising heating, alongside other solutions, including heat pumps and heat networks. Hydrogen could replace natural gas in the gas grid and therefore provide a like-for-like alternative for buildings currently heated by natural gas. However, 100% hydrogen for heating is not an established technology and so further work is required to understand the feasibility, costs and benefits ahead of Government making strategic decisions on the role of hydrogen in heat decarbonisation."

Electrification cases

Although using 100% hydrogen for heating and to run our cars appeals to be technically viable and the above energy efficiencies align with what we currently see in coal-fired power plants (30-40%) and natural gas combined cycle power plants (50-60%), I believe there is a better way ? electrification. Of course, hydrogen may make sense for large vehicles, like heavy-duty vehicles or trains for which the battery pack size would be enormous. But for smaller applications, this should not be a problem.

Let's consider the same case as above and consider 100 kWh produced from renewable energy. Again transportation, storage and distribution of electricity would involve losses. But these seem to be smaller (6%) than those for hydrogen (11%), yielding 94 kWh of electricity delivered.

When we use electricity to drive our car, we need to account for energy losses in AC/DC inverter (5%), battery charging (5%), DC/AC inverter (5%) and engine (10%). Consequently out of 94 kWh available from renewable energy, 72.5 kWh can be used in EVs. The energy efficiency of the overall process is 72.5%.

If we use electricity for domestic heating, we have two options - electric heaters or heat pumps.

For the electric heater, we know that the entire amount of electricity is converted to heat (i.e. efficiency of 100%). This means that out of 94 kWh of electricity delivered, we would receive 94 kWh of heat. The energy efficiency of the overall process is 94%.

For the heat pump, we know that current air-source heat pumps operate with COP of 1.5 (at the outdoor air temperatures of -15C; water delivery temperature of 50C) and 3 (at the outdoor air temperatures of 25C; water delivery temperature of 50C). I'd assume the average COP of 2.25 for further calculation. With that COP, the ASHP would transform 94 kWh of electricity into 211.5 kWh of heat. If I were to calculate the energy efficiency, it would yield 211.5%, which is mathematically incorrect but gives a clear idea of the technical viability.

In summary, conversion of renewable energy to hydrogen and its subsequent use for heating and transportation would result in energy loss of 34% to 44.5%, respectively. What does this mean? Our low-carbon energy supply would need to be almost doubled to cover these energy conversion losses. I guess we need to be smart about how we use our limited resources!

Hydrogen will be important still!

I always like to end each section with a positive message. Don't get me wrong, I do believe that low-carbon hydrogen will be important in the future, regardless of whether it's green, blue, pink or turquoise. For example, hydrogen will be important in our activities to decarbonise industries such as steelmaking, refining and petrochemicals production to name a few. And for such applications, we do need to find a way to produce low-carbon hydrogen at a low cost.

My team has recently published several studies on the production of hydrogen from biomass and waste via the sorption-enhanced gasification process. I will be sharing more detailed outputs over the coming weeks, once the studies are officially published.

Before I move to the academic career section of this newsletter, I'd like to ask you a question. Please leave your answers in the comments!

Do you think hydrogen will play a major role in decarbonisation of our economy?

Academic career

Making a decision to follow an academic career path is one of the biggest decisions you will make in your life? Why? Mostly because of the commitment that one must put in into overcoming the challenges associated with creating new knowledge and making a meaningful contribution to our society.

I've recently run a survey on LinkedIn (thank you all for so much engagement!) that asked "when is the best time to do a PhD". You can see the results after 4 days below (>4k votes).

Although this was not a scientific exercise, I can confidently say that majority think that having some experience before enrolling on the PhD programme is valuable. And I think I may know the explanation why this happens.

The obvious explanation would be that you've spent 3-5 tears at work and you can see the challenges and gaps in knowledge more clearly. Consequently, you decide to dedicate your time and effort to fill in these gaps. I saw such explanations in the comments and these are spot on!

But I believe there is a deeper reason why people do PhD after they got some initial experience. I believe it's that little voice in your head that kept asking you simple questions, such as:

• "why this happens?"
• "how does/en't it work?"
• "how this problem can be solved?"

This little voice pointed you in the direction of discovery and problem solving. It was probably there during your undergraduate and postgraduate degrees, making you extremely curious about the subject area of your interest. Sometimes, this little voice in our heads creates so much passion that you decide to dedicate your career to research directly after your masters. Sometimes, this little voice needs a bit more time to show you that career path.

From my perspective, I was always curious throughout my life - shy, but always wondering how things work and why they work the way they work. Me continuously asking questions "why" must have driven my parents crazy. My little voice kept relatively quiet during my first and second degree, but then something changed when I was working on my Master thesis. It was like someone switched on a lightbulb and my little voice said: "this is what I want to do for the rest of my life". So here I am, making it work through my academic career!

Unfortunately, some of us do get enrolled for PhD programmes for the wrong reasons, such as there was no better job opportunity. Don't get me wrong, I'm not saying you won't contribute through your PhD if you signed up for it because of this reason. It will just be more difficult to stay motivated and persistent in your pursuit of knowledge. After all, when creating new knowledge we all encounter issues and challenges, and it's the passion for discovery and our subject area that keeps us going.

For those on the verge, below are my articles where I share my reflections on why you should do a PhD and why you should pursue an academic career. I also share a guest article that you may find of interest!

If you want to contribute to my academic blog, check out the submission guideline!

Conclusion

I know hydrogen is a hot topic recently and everyone has a different opinion. I would love to know what you think of hydrogen and its applications. The numbers I presented above are high-level estimates based on the data I found in the literature, but the message is clear. Hydrogen isn't the silver bullet to global warming - at least if we want to sustainably use our resources.

I believe a project on sustainability assessment of various hydrogen production and use routes would make a wonderful Master or PhD thesis. Would you be passionate enough to get involved?

If you enjoyed my updates, please do subscribe and follow my work! You can also support my work by buying me a coffee!

If you did not like something, please do let me know too! Also, if there is anything specific that you would like to learn about, please do let me know!

Until the next time!

Dr Hanak

PS: If you enjoyed this newsletter and learned something new, share it with a friend!

PPS: If you need consultancy or training in green energy transition, industrial decarbonisation, carbon removal technologies, process design and process economics, I am open to discussing how we can collaborate together!