Hydrogen is on everyone’s lips. The European Union is promoting it through the Green New Deal and it is included in the Next Generation EU Funds. The roadmaps of large companies and public institutions for the coming years also include investment in this energy vector. Under this umbrella of popularity and economic funds, mega-projects worth millions in infrastructure for hydrogen production, transport and use are being presented. But what are the opportunities it offers and what are the pitfalls to avoid?
Javier Carroquino, founding partner of Intergia and Director of Technology and Strategy of the company, analyses the current situation of hydrogen and the possibilities that are opening up for its inclusion in the energy market, complementing electrification and coming from renewable sources.
One of Intergia’s lines of research is the storage of energy in hydrogen, produced from solar photovoltaic energy. The LIFE REWIND project, of which Intergia is one of the partners and was coordinated by Javier Carroquino, includes a demonstration prototype of solar hydrogen production and its use to refuel a fuel cell vehicle.
Hydrogen has become fashionable. It has leapt into the media and social networks and is on the lips of those who want to keep abreast of new technologies. Public administrations are talking about investing tens of billions. In view of this, those of us who have been working and researching in this field for years should rejoice. Or maybe not? Well, yes and no, because we are hearing and reading many completely wrong statements. In some cases, these errors stem from ignorance and in others from private interests far removed from the general interest.
First of all, the bad news. Let’s cool expectations.
First fact: the first thing to make clear is that hydrogen is not a source of energy. On our planet it is not found free, but combined in chemical compounds, one of which is water. For it to be useful to us, we have to obtain it by separating it from the other elements with which it is combined. This requires energy and, of course, money.
Second fact: hydrogen is only as clean as the energy it is produced with. According to this, it is assigned colours: black, grey, blue and green. Unsurprisingly, “dirty” hydrogen production is cheap. By contrast, “clean” production is expensive. Very expensive. Green hydrogen, the most expensive, is produced by electrolysis of water, with electricity from renewable sources.
«Hydrogen is only as clean as the energy it is produced with».
Third fact: if we use hydrogen as an energy carrier, we have to take into account the efficiency of the production process and the subsequent energy recovery. Speaking of green hydrogen, around 40% of the electrical energy used to produce it is lost as heat. If we then use the hydrogen to produce electricity in a fuel cell, we again lose about 50% of the energy as heat. In total, we have lost about 70% of the energy along the way. How much would have been lost if we had charged and discharged that electricity in a battery? No more than 15%.
Fourth fact: hydrogen storage is costly in energy (more losses) and money. If we store it compressed, pressures can reach up to 700 bar (same pressure as at a depth of 7,000 m under the sea) and the compressors have to be very specific. So do hydrogen tanks at these very high pressures. The energy for compression introduces new losses of more than 10%. If we store it in liquefied form, losses can be around 30%. Storage in metal hydrides also has losses and the loading and unloading process is anything but practical.
Fifth fact: What if we transport hydrogen in pipelines? Steel and other pipeline components would not withstand it and would be seriously damaged. It can be mixed up to about 15% with the gases currently transported, which are of fossil and non-renewable origin, but in this mixture it loses its purity and part of its economic value. On the other hand, transporting electricity is much simpler, more efficient and cheaper.
Sixth Fact: What if we use hydrogen in internal combustion engines? Just forget about it. The efficiency of internal combustion engines is extremely low and impossible to improve due to the theoretical limit of the Carnot Cycle. In addition, polluting emissions of nitrous oxide are produced, so hydrogen is no longer a clean fuel. The electric motor achieves efficiencies of up to 95%, weighs less, regulates much better and delivers much more torque at start-up. For all these reasons, it will turn the internal combustion engine into a museum piece.
Seventh fact: an energy system based on the hydrogen vector would require about four times as much primary energy as a system based on the electricity vector. It would be neither cost-effective nor environmentally friendly.
Now for the good part.
First opportunity: Large quantities of hydrogen are currently produced for non-energy industrial uses. To decarbonise the economy, it will be necessary to replace this currently black or grey hydrogen with green hydrogen.
Second opportunity: Conveniently stored, hydrogen’s energy density is higher than that of today’s batteries. This opens the opportunity for some mobility applications, such as heavy machinery, railways, shipping and perhaps aviation.
Third opportunity: Hydrogen can play a role in the huge storage capacity that the modern smart-grid will need. If production by means of electrolysers, medium-pressure storage and reversion by means of fuel cells are placed together, despite the not very high yields, it can turn out to be economical. Thus, at grid points and in periods of excess or cheaper energy, it would be stored in the form of hydrogen, to be returned when it is scarce or more expensive.
Fourth opportunity: research into electrolysers, storage and fuel cells. Research to increase performance and reduce costs. No mass deployment until improvements are achieved that make it reasonable.
«To decarbonise the economy, it will be necessary to replace this currently black or grey hydrogen with green hydrogen».
Will there be advances in hydrogen technology? Sure, but it has been researched for decades with limited results. It has a lot of room for improvement to compete as an energy carrier with electricity in most applications. The transport of electricity by cable is far more cost-effective than hydrogen in any form. For mobility uses, hydrogen only outperforms batteries in energy density, losing out in all other respects. In addition, new battery technologies offer very promising, although yet theoretical, results.
So what are the applications of hydrogen where it would make sense to invest? Certainly not as a generalised energy carrier if we want a clean and profitable energy system, and not in injecting hydrogen into pipelines. It is understandable that oil and gas companies want to replicate the production and distribution business model that hydrocarbons require. But it is not logical that the huge investment for this, with the associated uncertainties, should be paid for with public money, when there are much better alternative technologies.
Where to invest? In heavy machinery, railways and shipping. Also in applications where the heat lost in conversions can be harnessed. But, above all, in replacing black or grey hydrogen for industrial uses and in the storage of energy from renewable sources to stabilise the electricity grid. And, of course, in basic research.
PhD in Engineering
Master in Renewable Energies and Energy Efficiency