TriSOFC System

This page will provide a more detailed explanation of the system, its components and operation.

TriSOFC aims to define, develop and deliver low temperature solid oxide fuel cell (LT-SOFC) tri-generation technology in low carbon buildings for early market application. The project will be carried out as an integration of material, nanotechnology, device fabrications and stack unit constructions to system integrations, field-trials and public demonstration.

Technically TriSOFC aims to design, optimise and build a 1500 W low-cost durable LT-SOFC tri-generation prototype, based on the integration of a novel LT-SOFC stack and desiccant cooling unit. Additional components of the system are a fuel processor to generate reformate gas when natural gas is utilised as a fuel and other equipment for the electrical, mechanical and control balance of plant (BoP).  All these components will be constituents of the entire fuel cell tri-generation prototype system. The system will, at first be tested in the laboratory. Following further optimisation and miniaturisation, the TriSOFC system will be trialled in a real-life context at the Creative Energy Homes at the University of Nottingham. TriSOFC is primarily aiming at the low carbon building platform.

The table below sets out some of the key performance parameters of the TriSOFC project.

Parameter Goal
LT-SOFC Power 200 – 1,500 W
System efficiency (based on natural gas) > 90 %
Electricity efficiency (based on natural gas) > 45 %
Lifetime > 40,000 hours
Cost targets < 400 €/kWe

The proposed system utilises otherwise wasted heat from the SOFC to produce hetaing and and cooling, working as air conditioning for thermal comfort in buildings. This could lead to up to more than 90% energy efficiency and 70% CO2 emission reductions compared to a traditional energy production system comprising of separate condensate power plant, boiler and compressor-driven cooling units.

The SOFC device will be built with complete single-cell technology based on the breakthrough work on low temperature nano composite materials made by the partner KTH. The integrated membrane desiccant unit to produce cooling, heat and heat storage will be based on the work carried out by the University of Nottingham and IDMEC.

The complete TriSOFC system schematic is shown below.

TriSOFC system schematic

The proposed tri-generation technology has two unique features:

a)   The integration of membrane liquid desiccant system with fuel cell to provide electricity, space heating and cooling

b)  Use of desiccant solution as heat storage medium for fuel cell thermal control and management

These two innovations, together with the breakthrough in LT-SOFC technology, give the potential of the proposed tri-generation system developing into a versatile environmentally friendly electrical generation and thermal comfort system, with lower initial and running costs.

The SOFC technology

The LT-SOFC devices used in the tri-generation system will adopt the complete single-cell construction technology shown below. This novel single component layer structure is a breakthrough in fuel cell technology, and was achieved by TriSOFC partner Professor Bin Zhu and his team at KTH. The technological breakthrough was recently highlighted by Materials Views and Nature Nanotechnology. Compared to the conventional three-component design (see below), this novel structure consists of a homogeneous composite layer of a metal oxide and an ionic conductor. This layer works as a bi-catalyst for both hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR). The principle of this novel design is quite similar to a dye solar cell, where a mixture of electronic and ion conductors (electrolyte) is also used, and the charge and phase separations for the electronic and ionic conductions/phases can be successfully realised.

Schematics for a conventional three-layer SOFC device (a) and a single-component SOFC (b)

This streamlined design could significantly reduce the device expenditure and complexity, helping pave the way towards more cost-efficient fuel cells and competitive marketing. Furthermore, the single cell construction also facilitates a lower operational temperature operation, a particular advantage for building applications due to reduced system complexity, safety concerns and cost (less heat resistant materials).

The membrane desiccant unit

The membrane desiccant unit is powered by otherwise wasted heat from the SOFC. It dehumidifies the ambient fresh air in the membrane desiccant and storage unit. The dehumidified air then passes through the membrane evaporative unit where it is cooled down to the required air conditioning temperature. In the heating mode, the evaporative operation is not needed, and the air only exchanges the heat with returning air from the building.

Membrane desiccant unit

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