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AUTomotive deRivative Energy system

Periodic Reporting for period 2 - AutoRE (AUTomotive deRivative Energy system)

Reporting period: 2017-02-01 to 2019-04-30

Problem/Issue being Addressed: As a part of the AutoRE project, the aim was to further validate the overall system in a relevant environment (TRL5). In addition, innovative solutions were demonstrated to continuously improve performance and reduce costs and complexity.

Importance for Society: The targeted primary application for such a product is combined heat and power generation for commercial and industrial buildings requiring an installed capacity from about 50 kWe to some hundreds of kWe.

Overall Objectives: The main project objective is to create the foundations for commercialising an automotive derivative fuel cell system in the 50 to 100 kWe range, for combined heat and power (CHP) in commercial and industrial buildings. More specifically, the objectives are to:
a) develop system components allowing reduced costs, increased durability and efficiency
b) build and validate a first 50 kWe PEM prototype CHP system
c) create the required value chain from automotive manufacturers to stationary energy end-users
Overview of the Results: A 50kWe fuel cell CHP prototype system has been built at GE’s facilities in Rugby UK. Despite pre-commissioning of the Hydrogen Production System in Greece prior to delivery to the prototype test site, the integrated AutoRE system did not complete the planned 3000hr test due to early corrosion failure of the reformer combustion tubes. The presence of corrosion products in the combustion tubes caused the pressure drop to become too high, preventing the use of the Pressure Swing Absorption (PSA) systems tail gas in the combustion cycle. This significantly reduced the efficiency of the unit as only Natural gas was present as the combustion fuel and the tail gas produced by the PSA was effectively wasted. The electrical efficiency of the system was resultingly drastically reduced by this issue, with an efficiency of 5.8% at 53% capacity and 11.5% at 100% capacity. This compares to an expected efficiency with tail gas utilization of 36% at 53% capacity and 32.5% at 100%.
In addition to the testing of the 50kWe prototype system described above, lab-scale testing of component enhancements to the prototype system, to reduce its cost of electricity/foot-print and increase its performance has been carried out. Testing of selective membranes at SINTEF (to replace the Pressure Swing Absorber unit to produce high purity H2) with increased system efficiency has been completed. Compared to the baseline configuration, cooling and dehydration of the reformed natural gas feed before the H2 purification step are not required.
The final lab-scale testing carried out is that of short stack PEM fuel cell units at different operating conditions. Results obtained showed that upon switching from high purity hydrogen to a H2/CO2 mixture the fuel cell performance was highly affected. Increasing the proportion of CO2 reduced the performance of the fuel cell, although this performance was fully recovered when pure hydrogen fuel was re-introduced. A potential solution to CO poising could be injection of air (air bleeding) together with the reformate gas.
In parallel with the above test programmes, extensive modelling of the fuel cell based CHP system had been carried out, both for the baseline configuration and including future design improvements such as replacement of the Pressure Swing Absorber with a membrane-based separation system.
The results show that increasing the nominal power of the fuel cell has a positive impact on plant performance. However, careful economic evaluation is needed to analyze possible cost increases. The thermal integration of the reformer improves the plant performance without any drawbacks and should be adopted. Selective membranes integrated in the reactors (and not used as a standalone purification unit) allow significant efficiency improvements and plant complexity reduction, in particular if the membranes are integrated in the reforming side of the reformer reactor. Performance of a trigeneration plant (CHCP) based on the AutoRe cogeneration (CHP) unit on real energy management scenarios has been studied, together with the impact of two innovative technical solutions: (1) the advanced fuel processor designs, and (2) of thermally driven cooling machine has been assessed.
Additional modelling has also been undertaken to look at fuel cell degradation. This latter modelling activity has leveraged on the results of a previous project (SAPPHIRE) which also targeted a CHP fuel cell system. Fuel cell degradation mechanisms have been identified and described and some mitigation and diagnostic techniques have been proposed.

Exploitation: the focus of the exploitation of AutoRE results in the near term is to pursue a component exploitation strategy rather than a fully integrated CHP product. The particular components to be exploited are the natural gas reformer, the auto-derivative fuel cell and the membrane hydrogen separator. In addition, general project results and findings will be exploited thr
The expected impacts foreseen for AutoRE are as follows:

Electrical and thermal efficiency- Based on the modelling carried out, the target electrical efficiency of 47% can be achieved. By reducing the loading on the fuel cell within the system, effectively by including multiple fuel cells in parallel, the electrical and thermal loading targets can both be achieved.

Stack-life and maintenance- As noted above, the fuel cell could not be operated for the 3000h endurance test due to the early failure of the natural gas reformer. There is therefore no time-of -flight data to extrapolate to the target life-time of 30,000 hours and/or availability of 98%. Additionally, the life-time performance of the NuCellSys supplied PEM fuel cell in a stationary application is not known from sources outside of the AutoRE project. However, based on experience with bus driving cycles for the fuel cell, which are more arduous than the stationary application, it can be expected that >30,000 hours could be achieved. It should be noted however that the natural gas reformer is currently the technology which is driving the overall system life-time and durability and should be the focus of future component improvement efforts.
AutoRE prototype test facility signage/acknowledgement
Comparison between different scenarios in terms of economic saving through minimum cost strategy
Schematic overview of CHP power plant with membrane
Fuel cell short stack for lab-scale experiments
AutoRE prototype test facility in real life
Reformer corrosion products endoscopic inspection