A 50-year-old chemistry lesson

Cytec Consulting’s Paul Briggs shares his insights on the ever growing “hydrogen revolution” and the challenges and opportunities associated with a future hydrogen economy.

In this close to post-COVID world it seems as though all business, industrial and financial news is linked to the development of the circular hydrogen economy. Blogs and news sites are filled with mind-blowing investment promises in the hydrogen industry, and they are often linked with real programmes from governments and industry globally. There is an equivalent gold rush of money ready to be invested in decarbonising technology and the development of green energy. If time travel were possible and we had a visitor from the 1970’s, they would likely find it hard to believe we were ditching fossil fuels already and switching to the elusive element hydrogen as our primary source of energy. Elusive or abundant? Well, it is the most abundant element in the universe, so relative to that fossil fuel stuff we have an inexhaustible supply. Unfortunately, hydrogen is also one of the friendliest elements, attaching itself to other elements. It then becomes rather shy, or left alone, disappears into the upper atmosphere, but we will come to that later.

As an eager 15-year-old student, I remember setting up an experiment in our science class to produce oxygen and more importantly hydrogen. It fascinated me how you could turn water into its base elements with just an electric current. Of course, the best bit was setting fire to the hydrogen which ignited with a respectable bang. I guess the schoolboy finale isn’t allowed these days, but back in my day it seemed a weekly occurrence. A career in mechanical engineering with a focus on vehicle suspensions made that chemistry lesson a long-forgotten memory. Never did I think with the work that we have been doing at Cytec Consulting, would I need to rely on that experience. However, our current work with autonomous zero carbon vehicle concepts has brought me back to that long-forgotten chemistry lesson which continues to challenge me.

Hydrogen versus Battery

We have been looking at prime movers for this futuristic platform and hydrogen fuel cells take centre stage. They can represent the solution provided you believe. The three acts of faith, which are slowly coming to reality, are critical.

• Hydrogen made from renewable sources will be the same price as fossil fuels, or better still lower in price.
• Fuel cell power trains can be mass produced as competitively as battery power trains.
• The development of an effective widespread hydrogen distribution network can be achieved.

This would provide an environment where the fuel cell electric vehicle (FCEV) could compete with the battery powered electric vehicle (BPEV). We think without some form of parity, FCEV’s don’t stand much of a chance unless governments and industry subsidise them. We already have seen this in South Korea where the development of the FCEV cars is the direct result of the significant subsidy from Hyundai and the regional governments. Whereas a Tesla Model 3 BPEV is selling for $50k in South Korea, the Hyundai Nexo FCEV is selling for $30k but costs $84k to make (Bloomberg Businessweek 11/2021). This may seem like financial suicide, but such action is needed to create the demand for the infrastructure development. Meanwhile, fuel cell production costs must come down, not to mention the need for sustained affordable renewable hydrogen.

We kind of believe that efficiency of machines and their relative differences will play a part in their adoption. So, in the red corner we have the battery powered vehicle and in the blue corner, the fuel cell (maybe different shades of green would be more appropriate). If you provide 100 kWs of renewable energy to both systems, by the time you can use it to drive your vehicle, the BPEV is down to 80 kWs of available power. This is due to grid losses, charging/discharging and electric vehicle losses. This compares very favourably to a FCEV’s efficiency which would provide only 40 kW of available power due to electrolysis, hydrogen transportation, fuel cell efficiency and electric vehicle losses. This may be why Elon Musk appears to be so anti-hydrogen, as the figures don’t really add up in hydrogens favour. It seems you would only want to lose so much energy if the BPEV won’t hit the spot for you. This will be the case with heavy trucks, trains, ships and large aircraft. You just can’t carry enough batteries, due to the weight increase, to give you the range you expect with heavy vehicles.

Process evolution

So is the smart money moving into electrolysis? I assume that after 50 years; it has come on somewhat from my science experiment. Think of hydrogen as an energy carrier which you use when a battery isn’t going to meet the requirement, it all makes sense to suffer the efficiency loss of releasing the hydrogen from the water with electrolysis, and then returning it to electricity in the fuel cell. At its basic level, it allows you to use that surplus energy from renewables and make it mobile independent of a power cable that we have relied on since the 1880’s.

What is really bothering us is what do you do with the oxygen? Electrolysis splits the water into hydrogen and oxygen at a fixed ratio of 2:1 by volume (as in H2 O1) but more importantly 1:8 by weight. This means that for every kg of hydrogen we also get 8 kgs of oxygen. So, what’s the plan for the oxygen? Oddly the solution could come from fossil fuels! When coal, oil, natural gas or for the future, renewable fuels are burned in normal air, CO2 makes up around 3-15% of the waste gas. Separating out the CO2 is difficult and energy intensive. An alternative method is to burn the fuel in pure oxygen. In this environment, virtually all the waste gas will be composed of CO2 and water vapor. The water can be condensed while the CO2 recovered and stored underground.

The process is known as the Oxyfuel System and normally the challenge would be separating large volumes of air into oxygen, nitrogen, and other trace gases as this process can use up to 15% of the power produced at the station. Whereas if the power station is placed with an electrolyzer plant, the by-product is large amount of oxygen which could be used to fuel the system. Oxyfuel is more efficient for extracting the energy from the fossil fuel as heat isn’t lost in heating the nitrogen, and flue gases are 75% less than from air-fired combustion (Zhihua Wang, in Comprehensive Energy Systems, 2018). Could this be the answer while we transition our power stations from fossil to renewable fuels?

Meanwhile, Torvex Energy Limited, a small business located in of all places Fishburn, County Durham UK, announced in April they developed “a unique electrochemical reaction process that will revolutionize the efficiency and sustainability of green hydrogen production”. They say, “this game-changing innovation uses natural seawater to produce hydrogen gas in a simple step without the need for desalination costs”. They are patenting the process so understandably a little cautious in providing more details. With a limited understanding of the chemistry, I can only assume that the oxygen stays in the water which is no bad thing for the marine life. It seems like it’s only at the system demonstration stage, but they do say it will scale. With no contamination and a mass production efficient process, it could be a game changer. Imagine a string of giant floating wind turbines, well away from shipping lanes and in deep water, tethered together with a mothership or platform, generating electricity which is turned at source into hydrogen and shipped either as is or as ammonia or methanol directly to the customers. Sounds like this could be the perfect solution for us to make a significant dent in our carbon footprint. If so, County Durham might just become the next Klondike.

Environmental impact

Still, hydrogen does have a few dark sides to it. The development of the hydrogen economy will result in an increased leakage of hydrogen into the atmosphere. Even though hydrogen together with helium are the only gases which can under certain conditions escape earth’s orbit, they will still get stuck up there. Producing more hydrogen will inevitably mean more accidental leaks.
As hydrogen is lighter than air it will happily rise into the lower and upper atmosphere. In the upper atmosphere, hydrogen may moisten and cool the stratosphere, slowing down the recovery of the ozone layer. In the lower atmosphere, hydrogen may hasten the build-up of the greenhouse gases: methane and ozone and hence contribute to climate change. So, in this instance, hydrogen must be considered as an indirect greenhouse gas.

The hydrogen economy represents one of the few propositions that can viably provide a future replacement for the current fossil-fuel based energy systems. The future hydrogen economy has greenhouse gas implications and therefore isn’t a totally perfect solution, but it is likely the best option. If the future world hydrogen economy replaced current fossil fuels with a leakage rate of 1%, then it would produce a climate impact of 0.6% compared to what we have now. So, it will be important for the hydrogen world to minimize leakages of hydrogen right across the supply and user chain to ensure the full climate benefits occur. Given the cost of producing hydrogen in the first place, it would be better for the planet if hydrogen discharges were limited to emergency events only (Agage.mit.edu). While hydrogen technology developments are rightly grabbing the headlines, our current, proven affordable and competitive powertrain technology is pumping out the CO2 and NOX gases. The focus is rightly on zero carbon and with world government support for technology and deployment, this will surely come, and hopefully in time. But in the short term, is there more that could be done to clean up the existing technology?

Clearly, replacing every ship, truck, car on the planet has its own carbon footprint so it will be many years before we realize the benefits. After all, don’t these vessels and vehicles still have a viable life unless they just happen to be at the end of their useful life coinciding with the technological maturity of the solution to replace them?
Is conversion a viable de-carboning alternative, as hydrogen burning internal combustion engines with carbon (from burnt lubricating oil) and NOX capture, would be a big step forward without significant cost. These would be attractive solutions especially for heavier fleets or modifications for existing vehicles. The engine technology is already well developed and retrofit would be less complex than a switch to fuel cells. We then just need to develop the manufacture, storage, and delivery of hydrogen.

While the press and social media focus seems to be on transportation (which the EPA say was responsible for 27% of the total CO2 produced by the USA in 2020) it’s easy to forget the other contributing processes. But that will have to be somebody else’s problem as our focus and attention at Cytec Consulting is on our vehicle projects.
The need for autonomy does offer a valid reason to buy new rather than to modify. Although it’s possible to convert existing trucks to zero carbon and autonomous operation, it is far better to start from a new vehicle that can be optimized for the new technologies.

The prospect of a zero-carbon circular economy is a gigantic paradigm. It is going to be the reason and the catalyst for a complete relook at almost everything we do from fuel economy to end of life reuse. Engineering has suddenly become an exciting innovative place to be again and along with many others, Cytec Consulting are making a small contribution to future green transportation systems. Follow us for more updates!