With McPhy, Hydrogen storage gets kinky !!


             At a time when huge scale energetic issues are increasingly important without any concrete measures, like the COP 21 (agrofuel valuing, measures taken for a 1,5°C warming while they can practically limited a 3°C warming, measures avoiding multinational corporations in CO2 reduction, …), the more modest question of energy need is urging.

               The energy consumption is growing, led by industrialization, urbanization and motorization of non-OCDE countries should weight 70 % of global GDP growth and 90 % of the energy need growth. [1, 2]

Conso d'E + répartition

Figure 1 – A) Energy consumption by location in Tons of Oil Equivalent (Toe or Tep in french) ; B) Consumption by sector ; C) Consumption by source

               On top of this come limited oil ressources, with reserves that can satisfed a global consumption of 54 years, when gas reserves could do the job of 64 years, but with a monopolistic use of oil and a significative reliance on fossil resources (85 % of global energy), despite their reduction to 81 % by 2035. [2]

               It induces an energy transition and an orientation to renewable energies as a short and middle-term solution, however the latter show a lack of maturity (inadequate yield, expensive production of pollutant raw materials, …) and present a power generation risk, caused by an irregular generation (intermittency of wind/photovoltaic devices, …) which restrict their predictability over long-term periods, and could place electrical networks under stress, scaled to receive regular production (often surplus of 15 % due to nuclear and coal activity). [1]

Surplus de prod lié au renouvelable

                                     Figure 2 – Surplus electrical energy generation related to renewable energies

               Some solutions exist you ask ? Indeed, solutions are underway, as PHES (Pumped Hydroelectric Energy Storage), or CAES (Compressed Air Energy Storage) for huge amount of energy, and batteries or supercondensers for more humble volumes. But the latter are limited by their discharge time and their volume, CAES is limited by the existing storage places (example of salt caverns in Germany) allowing a significative storage but a significative energy loss during the expansion of compressed air, only remains PHES. Despite its monopoly (more than 99 % of installed electricity capacity storage in the world) for its installed power and modularity, is restricted by the number of geological sites, their grid connection, but more importantly the environmental impact of plants (drastic eco system changes). [1]

courbe temps décharge et puissance + moyen de stockage par puissance installée dans le monde

                      Figure 3 – A) Energy storage by power/time discharge ; B) Installed power repartition in the world by storage means

 

répartition conso mondiale par secteur

Figure 4 – World hydrogen consumption repartition by sectors

               To answer this, McPhy, a French Start-up created in 2007 in partnership with the CNRS and the CEA, chooses hydrogen (H2) storage in a new way, solid hydrogen storage.

               Hydrogen can be presented as an ideal energy storage solution (33 kWh/kg, which is to say 3 times more than 1 kg of fuel), neither pollutant nor toxic, this gas lighter than air allows a better diffusion and less risks. However, this volatility leads to a high pressure costly storage (between 200 and 700 bars) to obtain compressed or liquefied forms, which looses 10-25 % energy during the compression phase added to its explosive character have discourage numerous actors of the sector to use it despite its versatile applications, but solid storage solves these problems. [3-5]

 

 

step de formation des hydrures + volume de stockage d'un kg de H2

Figure 5 – A) Steps of metallic hydride formation ; B) Different states of 1 kg of hydrogen

               The principle of hydrogen storage is based on the capacity of some materials to absorb hydrogen in a reversible way, once hydrogen is exposed to a pressure of itself. Hydrogen under pressure switches between absorption/desorption (fixation on the surface of molecules/atoms on a fixed material) on the metal to diffuse itself inside the structure and create uniformly the metallic hydride, several metals are used (lanthanum, Titanium, Magnesium, Lithium) but are still in R&D phase. This reaction is very exothermic (which produces energy in the form of heat) because needing a slight pressure to have an efficient diffusion of hydrogen in the metal, it requests high temperatures (between 350 and 400 °C) and prove to be complex to set up. But McPhy while setting up this new storage, inhibits storage risks by energy produced recovering and transforming it in electricity. [1, 3, 6]

courbe temp-pression pour ads-desorp H2 sur Mg

Figure 6 – Pressure/Temperature diagram for hydrogen absorption/desorption on magnesium

               Besides this feat, McPhy chooses Magnesium hydride (MgH2) due to the affluence of magnesium, its price, recyclability, non-pollutant, and lighter among metals used for hydrogen solid storage. Despite the exothermicity of the storage, this method shows numerous advantages, by slowing down energy loss during storage (to 3 % against 15-25 % for compressed and liquefied), requiring only a few (or none) pressure and thus no equipment for without any additive maintenance costs. It allows a more important volume density (106 kgH2/m3 for the solid against 70 for the liquefied and 42 for the compressed) and an easier and safer transport due to the endothermic desorption (desorption which absorb energy), this will drop the temperature if the container is leaking and will stop hydrogen emission. [1, 3-6]

               McPhy supports more this storage solution with electrolyser coupling, the latter allowing to make oxygen and hydrogen by water electrolysis, which could be stored. [7]

 

water electrolysis

                              Figure 7 – Water electrolysis equation

 

Marché de l'hydrogène par source

Figure 8 – Hydrogen market by sources

               Hydrogen being mainly captive, the consumers are also the producers, the interest of McPhy is dual, propose a mid/long-term storage solution with the electrolyser/solid storage coupling to convert electricity surplus to gas (Power-to-Gas) and its storage, but also allow leading gas producers new storage/transport solutions and thus a better use for industrial/commercial purposes. [1]

 

 


References :

[1] McPhy Energy, Document de référence 2014, AMF, 2015

[2] Energy Outlook 2035, BP, 2014

[3] McPhy Energy, introduction Euronext Compartiment C, Portzamparc, 2014

[4] Clean and efficient energy storage : corporate presentation, McPhy Energy, 2010

[5] L’hydrogène, une nouvelle énergie pour la planète : présentation SEIN, McPhy Energy, 2014

[6] P. de Rango, D. Fruchart, P. Marty, Le stockage solide de l’hydrogène au service des énergies renouvelables, Images de la physique, CNRS, 2011

[7] N. Armaroli, V. Balzani, ChemSusChem, 2011, 4, 21-36

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Fabrice LEMARCHAND

Fabrice LEMARCHAND

Ingénieur en chimie et procédé, je manifeste un intérêt particulier au développement de l'innovation dans les environnements techniques/technologiques et structurels.

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