Friday, January 15, 2021

The Hydrogen-Based Economy: Is it Enough to Paint Something Blue to Make it Green?

A hopeful image for a hopeful article by Bertrand Piccard. "Blue Hydrogen" seems to be popular, nowadays. But is it enough to paint something blue to make it green? It turns out that "green" hydrogen, assuming it exists, is too expensive for what we need to do now in order to move away from fossil fuels and stabilize Earth's climate.

Hydrogen has come a long way since the time when it was discovered by Henry Cavendish as a component of the water molecule in the 1700s and then given its name of “creator of water” by Henry Lavoisier in 1783. It was later discovered that hydrogen is the most abundant element in the universe and the main component of stars.

Using hydrogen as a fuel is an old idea. It was, again, Cavendish who discovered that it can burn. The idea that hydrogen could be cycled as an energy storage medium is probably as old as the “fuel cell,” developed by William Grove in the early 1800s. In the 1950s and 1960s, the dream of "energy too cheap to meter" associated with nuclear technologies made it possible to think of hydrogen as an energy vector able to carry energy to the points of use, even vehicles, from a limited number of large nuclear plants. The first explicit mention of the concept of “hydrogen economy” was made by John Bockris in 1970. The nuclear promise never materialized, but the concept of the hydrogen economy was later linked to renewable energy. 

The idea of the hydrogen economy gained a lot of traction with the 2002 book by Jeremy Rifkin, titled “The Hydrogen Economy.” Conferences were held, research contracts were awarded, and prototypes were built. Sometimes, we saw lavishly illustrated pamphlets of the hydrogen-based world of the future, often depicted as something reminding the science fiction of the 1950s, except that it was quieter and greener. Then, it waned again when it became clear that the promises of clean prosperity could not be maintained except at stellar prices that no one was willing to pay. Today, we may be seeing a "third wave" of interest in the hydrogen economy. But is it a real possibility, or does it still remain in the domain of dreams?

Today, 50 years after the first mention of the concept of the hydrogen economy, and 20 years after Rifkin’s book, not a single application of the concept of cycling hydrogen as a fuel is present in the world’s economy. The “Hydrogen Car,” the fulcrum of the idea, found a recent incarnation in the form of the Toyota Mirai, but that’s hardly the kind of car that will replace conventional or battery-operated cars. After 6 years after having been introduced in the world market, there are maybe ten thousand Mirais running today in the world against some 10 million electric cars. Not a good performance for something that was touted to change the way people move in the world.

Things are not better for other facets of the hydrogen economy. Of all the prototype buses that would have used hydrogen as fuel, most can be found today in museums or have been scrapped – just a few seems to be still operational. The idea of using hydrogen as a large-scale storage system for the intermittent energy generated by renewable technology is too expensive to make sense. It simply doesn’t exist at present. We lack the network of hydrogen distribution stations envisaged as a necessity: there are maybe a hundred of them in Japan, maybe 30 in California. In the rest of the world, owning a Mirai is not a good idea. And nothing has happened of Rifkin’s grand idea that people would exchange hydrogen with each other using pipelines in the same way as people are exchanging data with each other using fiber optics cables.

In short, the hydrogen economy turned out to be 20 years (or even 50 years) of hype, but nothing that helped us to solve the problems that we face in terms of the desperate need we have to decarbonize the economy. It was at best a naïve idea. The costs and the problems involved were evident to everyone who looked at the matter in some depth.

What went wrong, then? A lot of things. Perhaps the main one was a basic misunderstanding in the way the idea was presented to the public. Free hydrogen is not an energy source; it is an energy carrier. Free hydrogen does not exist on this planet, so to create free hydrogen we must break the hydrogen bond in water molecules. That can be done using a technology carried electrolysis. It works, but it is not very efficient, it will always involve an energy loss that depends on various factors, but that is typically around 30%. So, hydrogen is a fuel, but it doesn’t come for free. You must pay for it and not so little. In practice, all the commercial hydrogen you buy today comes from the decomposition of natural gas, another process of limited efficiency. And that can’t help us much to get rid of fossil fuels since you start with a fossil fuel!

Then, there are lots of problems relative to how to store hydrogen. It is possible but expensive. Conventional steel tanks in which you store gaseous hydrogen suffer from the problem of embrittlement. Hydrogen atoms are so small that they diffuse into the steel making it fragile. You need different materials, typically more expensive ones. But, in any case, high-pressure hydrogen is not a good idea in terms of storage, especially in a vehicle. The tank would be huge, expensive, and dangerous. So, you can use cryogenic liquefied hydrogen that would still require a fuel tank of four times the size of a gasoline tank. In other words, a 30-liter tank of gasoline would be equivalent to a 120-liter tank of hydrogen. And you need to consider the energy needed to compress and liquefy the hydrogen, to say nothing of the unavoidable gradual loss from the tank, and from the danger that it poses. Hydrogen can leak from any container, no matter how well sealed it is. And liquid hydrogen will evaporate at a rate of around 2% per day.

Finally, there is a problem with the opposite side of the cycle, where you turn hydrogen back into water and energy. You can do that by burning hydrogen in a conventional thermal engine, but that’s so inefficient that it would make no sense. Indeed, the idea was, from the beginning, to use “fuel cells” – electrochemical devices that turn fuels into electric power. Fuel cells are normally efficient than thermal engines, but their efficiency is still limited, much lower than that of batteries. And fuel cells are expensive, the standard model that works at room temperature (PEM) need platinum as a catalyst at the electrodes. Platinum is a rare element, not only expensive, but that would be impossible to produce in amounts sufficient to replace even a fraction of the current park of road vehicles.

All that doesn’t mean that there are no niche applications of hydrogen that could be profitably used in the future. Maybe hydrogen could be a good fuel for ships, which have no problems with the need for a large and heavy tank. Or, hydrogen may be used for planes, although it would be impossible to couple with the current generation of planes that would need to be completely redesigned – not a task for the near future. And perhaps hydrogen could be used for large-scale energy storage. But all this is far away from the dreams of a prosperous and non-polluting hydrogen-based economy that were proposed in the early 2000s. 

All this is – or should be – known. Already in 2004, Joe Romm published a book titled “The Hydrogen Hype” directly conceived as a rebuttal of Rifkin’s 2002 book. Indeed, by the end of the first decade of the 20th century, the hydrogen economy seemed to be a dead duck. The collapse of the oil prices of 2009 and the advent of the apparently limitless “shale oil” in the US had convinced everyone that there were no problems with the oil supply for the near- and medium-term future. The idea of the hydrogen economy didn’t really die but went dormant, disappearing from the horizon of the energy events.

But, today, the situation has changed again. Depletion is making the extraction of fossil fuels more and more expensive. At the same time, we see the pressing need of decarbonizing the economy before it is too late to avoid a disastrous climate change. The fossil fuel industry is under heavy stress and the former miracle of shale oil is turning to be a canard. These are the probable reasons for the evident return of the hydrogen idea that we are witnessing today. It is not because new technologies made possible things that were not possible 20 years ago. It is, mostly a last attempt of the oil industry to propose a pie in the sky to retard the unavoidable demise of the polluting and unsustainable fossil fuels. The fossil lobby hopes that hydrogen will provide a niche for their products, counting on the fact that hydrogen – if we want it in large amounts – will have to come from fossil fuels for a long time. 

In short, hydrogen is not a good idea for the world of today. We need first to build up a real renewable infrastructure to produce energy. Only after that's accomplished, we could think of the luxury of using hydrogen to power cars and planes. For the time being, limited numbers of battery-powered vehicles, the concept of “smart grid,” and higher efficiency in every field, are the best way to go. We must move in that direction as soon as possible, without waiting for a pie in the sky that might never be within our reach.



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)