Christian de Perthuis, Paris Dauphine University – PSL
From Jules Vernes to Jérémy Rifkin, many were the visionaries anticipating the advent of a hydrogen society. Let's listen to the engineer Cyrus Smith, main character of The mysterious island (1875) :
« Oui, my friends, I believe that water will one day be used as fuel, that the hydrogen and oxygen which constitute it will provide an inexhaustible source of light and heat and of an intensity that coal cannot have. »
Long considered a mirage, hydrogen is making a strong comeback in the energy debate. The European Union recently published its hydrogen strategy. Et, in the thirty billion French recovery plan arrows on ecology, the two billion allocated to hydrogen constitute a real leap forward, multiplying by twenty the public money previously committed to this sector.
Could we be on the eve of a major revolution thanks to this gas discovered in 1766 by the chemist Cavendish?, then named “hydrogen” by Lavoisier?
If hydrogen is not the miracle of Jules Verne's novel, On the other hand, he can constitute a vector accelerating the energy transition towards renewable sources. On condition that we free it from its current dependence on fossil fuels.
Hydrogen of yesterday: a by-product of fossil fuels
Representing 75% of the gaseous mass of the sun, hydrogen is considered the most abundant element in the universe. On Earth, it is rarely present in its pure state: very light, it is in fact not held by gravitation and escapes from its natural reservoirs.
However, hydrogen is present all around us, combined with other elements. It is thus found in each water molecule. Associated with carbon, it is in all plants and animals. Fossil fuels, themselves resulting from the decomposition of living matter, are no exception.
Hydrogen can be produced by separating it from these other elements.
According to the International Energy Agency (AIE), we produce orders every year 70 Mt of pure hydrogen. The vast majority of this hydrogen comes from natural gas processing (69 %) and coal (27 %). Electrolysis of water and other pathways provide the rest.
From 1975, global hydrogen production has quadrupled (see graph below). The two main markets were oil refining – where hydrogen is used to desulfurize and purify fuels – and ammonia production., itself mainly intended for the manufacture of fertilizers.
This rapid development has in no way contributed to the decarbonization of economies.
On 2018, global production of hydrogen has caused the release of 830 Mt de CO2 in the atmosphere (Source AIE), i.e. the equivalent of 2.5 times CO emissions2 of France or 25% more than the rejections of all international flights of the year.
As long as hydrogen remains a by-product of fossil fuels, running on hydrogen or using it to produce heat helps reduce local pollution, but not to reduce CO emissions2.
The first challenge of the hydrogen revolution consists of switching to non-carbon production.
Tomorrow: gray hydrogen, blue hydrogen or green hydrogen?
“Grey hydrogen” refers to that obtained directly from natural gas or coal. Per kg produced, he issues the order to 9 Kg de CO2 from gas and 20 Kg from coal (see graph below). A Europe, almost all hydrogen comes from natural gas.
A first way to limit its carbon footprint consists of coupling its production with capture installations that recover part of the CO2 before it dissipates into the atmosphere. We then obtain “blue hydrogen”, limiting climate damage without freeing ourselves from dependence on fossil fuels.
Under current conditions, gray hydrogen costs around €1.5/kg in Europe, a little more than in the United States or China where gas and coal are cheap. Moreover, storage and transportation costs are limited by the proximity between production and consumption sites, most current installations being located in refineries or petrochemical complexes.
The cost of CO capture and storage installations2 is of the order of 1 €/kg. In other words, with a CO price2 of the order of €100/ton, it would become profitable to systematize these installations by switching from gray hydrogen to blue hydrogen. With the key, potential gains in CO emissions2 of the order of 750 Mt (2 % of global CO emissions2).
Another way to produce hydrogen is electrolysis, which uses electrical energy to recover the hydrogen present in water.. If you use electricity produced with natural gas or coal, the operation has no benefit for the climate: we release more CO in this way2 than by directly separating hydrogen from gas or coal.
By coupling an electrolyser to a carbon-free source of electricity, we obtain “green hydrogen”, non-emitting CO2.
The operation is particularly interesting, when we have significant wind or solar production capacities whose unit production cost has become competitive, both in the face of fossil and nuclear sectors, but whose large-scale injection comes up against the difficulty of intermittency. Electrolysis then makes it possible to store excess electricity by transforming it into hydrogen which becomes an integrator of renewable sources in the energy system..
How to make green hydrogen competitive
The cost of producing green hydrogen by electrolysis depends on three parameters: the price of electricity used in the electrolyzer, the cost and effectiveness of this electrolyzer, the transport and storage costs which weigh in the balance as soon as the place of consumption is far from the production site.
Currently, the cost of a kg of green hydrogen is in a range of around 3 at 6 €/kg, i.e. two to four times that of gray hydrogen. But it is in a sharp decline dynamic, under the impact of the drop in the cost of green electricity and that of electrolysis.
The various hydrogen plans aim to accelerate the movement thanks to changes in the scale of electrolyser production and investments in storage and distribution networks.. This public money mobilized on the supply side makes it possible to accelerate the industrialization of pilots resulting from research and development. Its use is fully justified.
Aid for the use of green hydrogen in the form of a price supplement is more questionable from an economic perspective. They do not sufficiently encourage producers to lower their costs and stimulate energy consumption. They could be greatly reduced or disappear for a price of CO2 of the order of 100 at 250 €/T.
The production of green hydrogen from renewable biomass is another path that could prove interesting for its territorial integration.. It is still in the experimental stage.. Two options are being tested in France: from wood (projects of Vitry-le-François and Strasbourg) or from agricultural biomass (use of hemp in Sarthe).
New uses of hydrogen
To fully contribute to energy substitution, it is not enough to scale up the production of green hydrogen. It is also necessary to develop uses that make it possible to reduce CO emissions.2 where they are most difficult to obtain.
In the first place, we can inject up to 10 or 20% green hydrogen in gas networks, significantly more if we convert part of this hydrogen into methane via a process called “methanation”. This way is currently being tested in France in Fos-sur-Mer. In addition to the interest in reducing the share of fossil gas in the network, its interest is to be able to capture and reuse part of the CO emissions2 of the Fos steelworks.
Second, hydrogen makes it possible to produce electricity from on-board fuel cells. Asian manufacturers Toyota and Hyundai have started to market hydrogen passenger cars which have a greater range than electric cars using batteries. Eventually, the most interesting applications concern utility vehicles (bus and truck) for which the weight of the batteries is a major constraint, trains when the lines are not electrified and, probably later, the planes.
At last, green hydrogen could tomorrow decarbonize industrial processes where substitutes for fossil energy are difficult to develop. The most important concerns the primary production of steel where coal is used both as a source of energy and a reducing agent for the ore.. Hydrogen could replace it and provide zero-carbon steel. The first industrial pilot testing this route is under development in northern Sweden, as part of the project Hybrit.
Europe facing the hydrogen revolution
The European hydrogen strategy emphasizes the development of a competitive offer based on support for R&D, industrial pilots and projects integrating hydrogen into broader ecosystems. Thanks to different investment programs, Europe has put several tens of billions on the table.
The new attention paid to supply constitutes a major shift in European climate policy which has until now been based more on supporting the use of carbon-free energy than on its production on European territory..
Such actions promoting demand have succeeded, in the case of solar energy and batteries, to relocate a large part of equipment production while losing potential for local creation of wealth and jobs.
L’Germany, and now the The Qairos Energies hydrogen and biomethane production project soon to be tested, decline this European strategy, planning to invest respectively 9 and 7.2 billion in public money from here 2030.
They have significant advantages, with two of the three majors in the global industrial gas industry (Linde and Air Liquide), major automotive or railway equipment manufacturers, excellent public research laboratories and a myriad of start-ups, many of which originate from these laboratories. Germany relies on faster plan to deploy renewable energy, essential support for green hydrogen.
The key to success will be less the quantity of public money put on the table, that the ability to bring together all these actors from different backgrounds in synergy. It is at this price that we will make hydrogen, not this “inexhaustible” energy that the engineer of The mysterious island, but a powerful integrator of renewable energies in the energy system of tomorrow.
Christian de Perthuis, Economics professor, founder of the “Climate Economics” chair, Paris Dauphine University – PSL
This article is republished from The Conversation sous licence Creative Commons. Read thearticle original.