The Green Hydrogen Lab at UniBO

Introduction

Experimental characterization of green hydrogen technologies in different operative conditions is critical for accurate techno-economic analysis. Although some values exist in the literature, they typically refer to standardized conditions that are usually far away from real-field operations.

Objective

To cover this gap, the Green Hydrogen lab at UniBO allows the experimental testing of Power Gas technologies. The scope is the empirical calculation of the main relevant Key Performance Indicators (KPIs), such as energy consumption. Based on the analysis of the calculated KPIs, correlations are proposed to estimate the performances of the P2G plants’ components as a function of the expected operative conditions.
The results are given as input to the developed planning tools for techno-economic analysis.

Methology

Several experimental performance tests can be performed to simulate different operative conditions like, for example, steady and unsteady state or to evaluate their effect on the performances.
The lab consists of two cabinets: the process and the data acquisition sections are separated for ATEX reasons. To date, the process cabinet includes the following:

• A 7.5 kW electrolyzer.
• A hydrogen compressor (from 2.5 bar to 36 bar).
• One buffer storage between the two devices.
• One storage tank (83 liters) at high pressure (36 bar).

The plant design allows substituting these elements with others increasing the flexibility and the potential applications. Accurate measuring devices like, for example, flow, pressure, temperature, and electric power transmitters, are installed in the process, measuring thermodynamic and electric consumption conditions every 5 seconds and sending the value to the data acquisition for future analysis. The following measurements can be performed:

• Input electric power
• Input power of compression
• Cold and Hot start-up time and energy
• Response time and ramp energy
• Shut-down time and energy
• Switch-over time
• Hydrogen output rate and quality
• Oxygen output rate and quality

Figure 1. The measuring components.

Figure 2. The process cabinet.

Analysis

Figure 3. The Process Flow Diagram of the lab.

Different analyses can be performed with the data measured through experimental tests. First of all, KPIs are identified. Examples include specific energy consumption, hot and cold start-up time, degradation, etc. Correlations and trends between the identified KPIs and the operative conditions are investigated.
For this purpose, different tools can be used. From theoretical analysis, simple or more sophisticated analysis can be performed using complex methodologies and tools such as machine learning.
The outputs of the analysis are used to perform techno-economic analysis like a feasibility study to find the optimum sizing of P2G plants, optimize control strategies, or define the best management strategies.
Based on the principles of the Internet of Things (IoT), the development of simulation tools like the design of digital twins can be performed and validated in the lab for application to the field and more complex plants.

Results

Preliminary KPIs of market P2G technologies were investigated in the Lab, comparing them with the state-of-the-art values and giving techno-economic inputs to the SuperP2G-Italy tools.
For example, sensitivity analysis to investigate the Levelized Cost of Hydrogen (LCOH) is the next step, as shown in the figures below, for different electricity purchase costs and P2G plants consumption as calculated by the measured experimental values.

Figure 4. LCOH for different electricity purchase cost assuming real performances as inputs in the optimization.

Digital twins of each component are also designed and validated. In the figure, the pressure in the storage tank as a function of time is shown. While not shown, many inputs are elaborated by the digital twin to simulate the operative parameters. Thanks to the innovative model, very small errors are achieved. In this specific case, an error small than 2% is obtained.

Figure 5. The simulation performed by the designed digital twin simulating storage section.

Conclusion

P2G plants and components optimization is essential in the following years to compete with grey and blue hydrogen. Experimental activities could answer both the question of increasing performance and optimizing the entire green hydrogen value chain.
Therefore, having experimental data is essential. For this purpose, the Green Hydrogen was designed to make a certified and safe research infrastructure available to stakeholders for testing and investigation. Thanks to its flexibility, many P2G devices can be installed and operated. Therefore, while know-how increases, the risk of investment failure will decrease, ensuring P2G technologies’ market uptake.

References

The Green Hydrogen Lab:
https://site.unibo.it/superp2g-italy/en/the-green-hydrogen-lab