Considering the prospected evolution of the gas network in Europe, and the fuel alternatives for residential-commercial-scale SOFC-CHP, likely fuel compositions for the midterm future can be rationally defined. Current gas grid infrastructure regulation relies a lot on safeguarding down-stream appliances (often combustion-based) in terms of the Wobbe Index and other parameters. Large-scale field demonstration projects have shown, however, that up to 20% H2 by volume will not impair most appliances currently connected to the gas grid. Above this limit, all down-stream appliances would have to be changed, therefore one may go directly to 100% H2. 20% H2 by volume is however a very small contribution in terms of energy and will not achieve significant CO2 reduction for equivalent energy transfer. It is important to evaluate which NG-H2 compositions can be viable all things considered, and in the meantime appliances that are fully fuel-flexible will guarantee a smooth transition to any finally to be established range of energy carriers.
The overall objective of SO-FREE is the development of a fully future-ready solid oxide fuel cell based system for combined heat and power generation. This means a versatile system concept for efficient, near-zeroemission, fuel-flexible and truly modular power and heat supply to end users in the residential, commercial, municipal and agricultural sectors.
Beyond the primary objective required by the call topic – i.e. the delivery of a pre-certified SOFC-CHP system allowing an operation window from zero to 100% H2 in natural gas and with additions of purified biogas – the project will endeavour the realization of a standardized stack-system interface, allowing full interchangeability of SOFC stack types within a given SOFC-CHP system. This interface design will be taken to the International Electrotechnical Commission as a New Work Item Proposal for international standardization.
The prototype will be operated to assess compliance with applicable requirements at TRL 6, defining the outstanding pathway to full product certification; then it will run at TRL7 (demonstration in operational environment) providing combined heat and power with natural gas with injections of H2.
Two stacks will be operated (sequentially, by replacing one with the other) within the final prototype, that cover the spectrum of SOFC operating temperatures: 650°C (Elcogen) and 850°C (IKTS).
