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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - Bio-HyPP (Biogas-fired Combined Hybrid Heat and Power Plant)

Teaser

Summary

The main objective of this project is to develop a full-scale technology demonstrator of a Hybrid Power Plant with 30 kWe suitable for gaseous sustainable biomass feedstock. The aim of the demonstrator is to prove the functional capability as well as to achieve high system efficiency with respect to fuel flexibility and optimized subsystems and subcomponents. The technical objectives of this project are specified in terms of controllable measures of electric and thermal efficiencies, operating range, operational flexibility, exhaust gas emissions and market and cost reduction potentials of the hybrid power plant.
Bio-HyPP, the Hybrid Power Plant concept, is a combination of solid oxide fuel cells and a micro gas turbine. It is a technology solution for a biogas-fired combined heat and power (CHP) system addressing effectively requirements for highly-efficient, highly load- and fuel-flexible CHP systems with lowest emissions. The technology concept enables enormous savings of CO2 by minimizing the consumption of biogas or natural gas. Thanks to the high operational flexibility it could act as a sustainable, variable, renewable electricity generation, which is predictable and grid friendly. The goal of the project is to demonstrate the Hybrid Power Plant concept as a reliable, cost-effective and fuel-flexible micro-combined heat and power system.

Work performed

Three business models and the three most promising feedstocks have been identified. A screening of Life Cycle Cost has been done on the manufacturing and use phases of a system composed by Bio-HyPP system components. Also, safety requirements for the laboratory in Savona (Genoa) for the top-economic layout have been analyzed and defined.
For the top-economic layout a steady-state model has been developed and components have been specified by this model. A compressor has been chosen for off-design analysis considering the turbocharger control. Dynamic models have been developed and have been utilized for simulations to gain insights on valve control for the hybrid power plant.
A steady state thermodynamic model of the top performance has been developed and refined with detailed knowledge about heat losses and has been used for refined boundary conditions.
A combustion system, which meets the needs for both SOFC off-gas combustion and biogas/natural-gas-fired combustion has been developed, manufactured, tested under atmospheric conditions and analyzed concerning the operating range. To widen the operating range, adding excess fuel has been analyzed. The combustor for the MGT hybrid test rig has been designed and manufactured.
MTT turbomachinery has been improved and successfully tested on the standalone micro gas turbine EnerTwin. Also, a prototype for a high-speed generator has been designed and pre-tested and is currently manufactured. Air bearings together with the whole power module (turbine, compressor, generator and bearings) have been designed and parts have been manufactured and tested. A simulation model for the air bearings has been set up and validated with the test data serving for concept refinement.
Experimental tests and additional analysis of the recirculation blower have shown that the recirculation blower is suitable for controlled operation for methane and biogas operation.
Two recuperators, one for the top-efficiency-layout and one for the top-economic layout, have been designed.
The existing emulation facilities have been upgraded. Experiments have been used for model verification and an operating strategy has been proposed. Surge investigations with different volume sizes and start-up procedures have been analyzed experimentally. Control strategies including fuel cell degradation have been studied.
Two real subsystems with emulation of the other component have been set-up and assembled: the MGT hybrid power plant and the SOFC hybrid power plant. Two control systems have been developed and are currently used for the commissioning of the system. To investigate the influences of one system onto the other, hardware in the loop model representing the fuel cell functions has been set up. For the top-economic layout a test rig to measure performance of turbochargers in cold and hot conditions was built, turbochargers have been tested experimentally and the turbocharger for the top-economic test rig has been chosen.
A communication and dissemination strategy of the project has been outlined. The project website has been updated with the latest information on the project constantly. Four newsletters have been published. The Bio-HyPP Consortium has participated at several international conferences and workshops. A Stakeholders Group has been created; their perspectives and expectations have been collected and analyzed. Activities have been devoted both to the planning and to the development of future exploitation strategies. All activities are supported by a robust project management structure using effective processes and tools.

Final results

Since all the tests carried out with prototypes so far (companies and researchers) were not able to reach the design performance, an important target is the achievement of 60% efficiency. The impact of biogas will contribute to the possible exploitation of such a kind of renewable fuel in power generation technology.
The direct benefits of pressurization of the fuel cells are reduced pressure drops resulting in a reduction in stack volume and increased cell performance.
An integrated control system has to be developed to ensure a reliable operation of the coupled subsystems. The control concept will be tested on the system emulators before the coupling â€“ resulting in insights on control necessities for the specific components used - this has not been done in other hybrid power plant prototypes.
Additionally, a combined SOFC off-gas and micro gas turbine combustion system is designed for high fuel flexibility, high load range as well as a large temperature range. Components for compressor and turbine are designed for wide operability limits for low moments of inertia, in order to guarantee good transient behavior. The design aim is to develop components for high peak efficiencies. Experimental investigation showed more than 2%-points efficiency increase of the micro gas turbine.
The wider societal implications are based on expected findings around the compressor surge with large cathodic volumes, currently an unexplored field but holding the potential of impacting on the whole international scientific community. The expected implications are also based on oil sleeve bearings being replaced by air bearings, significantly reducing friction losses, resulting in higher shaft levels. Even if not being integrated into the hybrid system in the end, these bearings will be integrated into the gas turbine in stand-alone mode, resulting in knowledge about air bearings for small sized systems. Further implications are the high-speed generator concept with toroidal winding structure, which is expected to give better performance in comparison to more conventional concepts. Also the redesign of the recuperator to fulfill the required low loss requirements and to reduce manufacturing costs will have a big impact on knowledge about heat exchangers in so far unknown Reynolds-regions.