WP 1
WP 1
Optimisation of the materials: compositions for hydrogen purification and compression and for heat storage
Optimisation of the materials: compositions for hydrogen purification and compression and for heat storage
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This objective focuses on the development of new metal hydride (MH) compositions on a laboratory scale. The materials will be developed starting from the state of the art and optimising their properties with targeted composition variations, adapted to the application objective, in particular by adjusting the type and quantity of alloying elements.
The main focuses are on the following point:
H2 purification;
H2 storage;
H2 compression;
Heat storage
Heat management.
In addition, a complete characterisation of the materials produced will be carried out to determine: i) gravimetric and volumetric density of hydrogen, ii) most favourable conditions for activation, including on an industrial scale, iii) pelletisation with a view to the production of hydride cylinders.
Finally, modelling will be carried out using ab initio and Calphad calculations in order to identify the compositions with the best properties.
The WP 1 is divided in 5 tasks.
WP 1.1 PURIFICATION
WP 1.1 PURIFICATION
The separation and purification of hydrogen is based on selective absorption by MH, which is capable of separating hydrogen from contaminants, water and moisture in a gas stream.
This system guarantees reliability and good levels of purification efficiency.
MHs may suffer reductions in storage capacity in the presence of moisture, O2, COx, sulphur and other impurities. It is therefore essential to study materials that can act as purifiers of impurities, in order to preserve the purity of the alloys in the subsequent stages of storage and compression.
The composition of AB5 alloys (e.g. MmNi5) will be adapted by replacing other elements, identifying the best compositions in terms of number of elements and quantities.
WP 1.2 STORAGE
WP 1.2 STORAGE
The advantages of storing hydrogen in MH compared to compressed gas are intrinsic safety, higher volumetric density (110 vs 30 kg H2/m3) and greater energy efficiency (around 85% or more with heat recovery and the use of “free” thermal sources).
With a view to reducing material costs and improving the thermal management economy of absorption/desorption at temperatures close to ambient temperature, TiFe-based alloys will be studied with appropriate substitutions of V and/or Mn or other elements that reduce storage temperatures while increasing gravimetric capacity.
WP 1.3 COMPRESSION
WP 1.3 COMPRESSION
The advantages of using MH for hydrogen compression compared to mechanical compressors (powered by electricity) include the absence of contamination (e.g. oil), reduced space requirements, no moving parts, reduced maintenance costs and noise, and, even when using heat from external sources (e.g. concentrated solar power, waste heat, etc.) for MH thermal management, very low energy consumption.
In this project, suitable MHs will be identified to achieve p=350 bar at temperatures below 120 °C; MHs with rapid absorption kinetics to allow short compression times will be selected and the optimal combination of MH for the three stages of the compressor, to minimise energy consumption, will be selected.
AB2 alloys (e.g. TiCr2 and TiMn2 with Mn, Ni, V, Fe substitutions) will be considered.
WP 1.4 HEAT STORAGE
WP 1.4 HEAT STORAGE
Heat can be stored reversibly in MH, which have the potential to meet targets related to cost (less than €15/kWhth), energy efficiency (greater than 95%), operating temperature (less than 200 °C) and volumetric energy density (greater than 80 kWhth/m3).
A functioning MH will be developed in a temperature range of 100–200 °C, characterised by an energy density greater than 100 kWh/m3 and a gravimetric capacity greater than 1% by weight, to effectively recover thermal energy supplied by an external source.
Several MH AB5 (e.g. MmNi5) will be tested because they operate in a temperature range close to ambient, storing more than 100 kg H2/m3.
WP 1.5 HEAT MANAGEMENT
WP 1.5 HEAT MANAGEMENT
In analogy of what happens for heat storage, MHs systems can be used as heat exchangers.
In this project theoretical methods will be used, such as ab initio calculations and Calphad, will be used to support the experimental part, in order to identify the most suitable compositions for the applications defined in the previous tasks and predict the properties of the metal hydrides studied.
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