Hydrogen is today more the domain of industrial chemistry than of energy or mobility (the word does not appear in particular in the index of the energy manual of Jean-Pierre Hansen and Jacques Percebois) . Hydrogen is economically above all, and from a very long distance, hydrogen applied to the industry, hydrogen-industry.
This situation could change in the coming years. On the one hand, hydrogen could help solve the problem of renewable energy storage: it is hydrogen-energy. On the other hand, hydrogen could be used for heating, and be part of the low-carbon mobility, especially as a fuel of motor batteries: it is the hydrogen-mobility … a potential rupture that requires in advance to decarbonize the production of this energy vector.
In a more distant perspective, hydrogen, which consists of certain filaments that cross the cosmos, could also be involved in the context of nuclear fusion for civil use (through its isotopes). But I will not discuss this theme here.
1. Hydrogen production: from carbon capture to total decarbonation
1.1. Hydrogen production
The methods of producing hydrogen (more precisely, hydrogen dihydrogen) are numerous. The main industrial method of producing hydrogen is currently steam reforming hydrocarbons (non-renewable) such as methane. This method also produces CO2.
The industrial production of hydrogen is 900 kT in France and 50 M kT in the world (1). The production of this hydrogen called “gray” releases 10 kg of CO2 per 1 kg of hydrogen produced (2) … or 500 million tons of annual CO2 emissions worldwide, out of a total global emissions estimated at about 37 billion tons.
CO2 capture is the main technological pathway for reducing CO2 emissions associated with the production of hydrogen from hydrocarbons. Major industrial players today know how to implement solutions of this type. However, they also make production more expensive. In addition, this is “blue” hydrogen and not “green” decarbonized hydrogen. Indeed, as stated in the recent call for projects of the French Environment and Energy Management Agency (ADEME), devoted to the development of the hydrogen sector, low-carbon hydrogen is defined as on the one hand, from renewable energies, and on the other, transported by minimizing CO2 emissions.
There are currently two industrial methods (3) for producing decarbonated hydrogen, and a large number of experimental methods. The main industrial method is the electrolysis of water (“power to gas”). The principle of the electrolysis of water admits many variants (more or less well established), playing on the parameters of temperature, pressure, modifying the cell (there are more than fifteen types of possible cells).
Another method is the Kvaerner process, which involves heating a hydrocarbon to 1600 ° C with a plasma torch.
The main experimental runs of green hydrogen production are as follows:
- Biomass gasification
- Biological processes: fermentation, photosynthesis …
- Thermolysis (cracking water at 850 °).
- Chemical and thermochemical reactions
The high heat often required to produce hydrogen can be provided by a cogeneration device, applied for example to a nuclear power station (4).
The transition from the experimental stage to the industrial stage could take place in the coming years for many of these technologies. Currently, carbon-free hydrogen is two to three times more expensive than hydrogen produced from hydrocarbons.
1.2. Hydrogen storage
The mode of storage of hydrogen is not obvious as is for example that of oil. With an atmospheric pressure and a temperature of 25 ° C, the hydrogen has a density of 0.09 kg / m3, making its storage difficult to pass.
Three solutions exist, all expensive:
- Storage in the form of compressed gas (pressurization up to 700 bar), allowing a density of 42 kg / m3.
- Storage in liquid form (cryogenization at -252.8 ° C), allowing a density of 70 kg / m3; there are also liquid vector projects that can be loaded with hydrogen.
- Storage in solid form, in particular of metal hydride (absorption of hydrogen by a metal), allowing a density of 106 kg / m3.
2. New energy applications of hydrogen: storage, heating, mobility, etc.
Hydrogen is 95% hydrocarbon and today it is used in a wide variety of industrial processes: production of ammonia for fertilizers in agriculture, oil refining (desulphurisation in particular), chemistry (methanol production). for example), as well as in space (5), metallurgy, glassmaking, etc. For all these applications, market demand already exists.
New applications in the areas of energy storage, heating, and mobility could be added to existing applications in the future. Currently, the market demand for these applications is still relatively limited. In addition, the justification for these new applications is largely based on the use of green hydrogen, the production of which is just beginning.
The general principle of all these applications is the fuel cell (PAC) (6), which makes it possible to produce electricity and heat from hydrogen and oxygen. Invented in the nineteenth century and constantly improved since until becoming exploitable for practical uses in the 1950s, the CAP is still the subject of significant R & D efforts, aimed in particular at reducing the use of platinum as a catalyst.
2.1. Hydrogen at the service of renewable energy storage
Renewable energies often operate intermittently, which poses a problem of storing the energy produced during periods of low consumption. Hydrogen is a candidate to help solve this problem. I refer in this regard to the technological sheet dedicated to this subject published last year on open-organisation.com.
2.2. Heating with hydrogen
It is possible to use a fuel cell to heat up while producing electricity. More generally, hydrogen can play a role in heating networks, as shown in the fact sheet on new heating and cooling technologies that has just been published on open-organization.com.
2.3. Hydrogen mobility
Mobility generates 30% of greenhouse gas emissions.
The application of hydrogen to mobility can follow two paths, which are otherwise hybridizable. The first is that of the internal combustion engine using dihydrogen as fuel. The BMW Hydrogen 7 (2006) is the first production car of this type. This path does not seem to be favored at present by the industrial actors (7).
The second way is that of the CAP (which can be combined with other energy sources), and it is the one borrowed in the context of a large number of applications:
- Aeronautics: Air transport is the most environmentally damaging. Hydrogen can contribute to the reduction of greenhouse gas emissions from this sector, and several projects exist to develop a transport aircraft that operates entirely or partially (systems ancillary) to hydrogen.
- Drones: projects exist to increase the autonomy of drones via PAC.
- Flying car: Hydrogen flying car projects exist.
- Water Transport: Operational hydrogen ships already exist, and many new ship projects are under development. Let us also mention the two hydrogen-fueled hydrogen promotion boats, the Energy Observer, supported by the French Government and the Race for Water, financed by a Swiss entrepreneur. The Energy Observer is supported by Toyota and must arrive in Tokyo on time for the 2020 Olympic Games.
- Submarine: the HDW Type 212 military submarine runs on hydrogen.
- Train: Alstom has launched the first hydrogen train for regional travel to replace diesel locomotives. It was launched in Germany about a year ago.
- Urban Buses: Hydrogen city bus models exist on the market.
- Coach: Flixmobility is currently developing a hydrogen coach with Freudenberg Sealing Technologies.
- Truck: Several models have been or are about to be marketed in 2019, especially those of Hyundai, Kenworth / Toyota, and the startup Nikola.
- Handling vehicles: The logistics sector is being conquered by models of hydrogen-powered stackers, pallet trucks and forklifts. Amazon has acquired the manufacturer of PAC Plug Power.
- Car: The three most active automakers are Toyota, Hyundai and Honda. Hype taxis are Mirai models built by Toyota. Other manufacturers are testing. Hybrid models also exist: the Symbio company offers hydrogen kits to extend the range of electric battery vehicles.
- Velocipede: Pragma Industries markets hydrogen bicycles.
Still from the principle of the CAP, hydrogen at low pressure can be enough to power with a high level of autonomy of small electrical devices such as a smartphone.
Finally, green hydrogen can be injected into the natural gas network, allowing hydrogen consumers to reduce their carbon footprint.
Our hydrogen panorama suggests that the new applications of hydrogen, and the production of green hydrogen, are attracting considerable interest, particularly in countries such as Japan, China and Germany. French companies are also very innovative in this area. Although probably less present in people’s minds than new electric batteries, hydrogen has the technological potential to play a central role in the energy transition.
(1) Estimates range from 50 to 70 million kT.
(2) The formulas that characterize the two main reactions involved in methane steam reforming are as follows:
CH4 + H2O → CO + 3H2
CO + H2O → CO2 + H2
Knowing that the molar mass of CO2 is 44.01 g / mol, and that of H2 2.01588 g / mol, the difference in mass corresponds to a factor of 5.47 approximately. The factor of ten used above includes other emissions related to the industrial process.
(3) Not to mention the production from coal, at the origin of the expression gas plant. The last gas plant in France closed in 1971.
(4) Note that there are also alternative projects for the production of zero-emission hydrogen from hydrocarbons (pyrolysis of methane, injection of oxygen into oil sands, etc.).
(5) Space is the sector for which modern applications of hydrogen, particularly energy, were developed and industrialized first in the 1960s and 1970s. It is also, until now, the only sector able to bear the costs of high exploitation of this energy vector.
(6) There are many types of PACs. Among the most exotic: the PAC based on urine and nano-aluminum powder, resulting from US military research.
(7) Moreover no one remembers the Hydrogen 7.
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