Cost Requirements for a Small-Scale SOFC Fed From Agricultural-Derived Biogas

In this work, the use of fuel cells for valorizing agricultural-derived biogas in Switzerland is studied. The Swiss agricultural case is characterized by farms with small numbers of animals (20 cows) and high feed-in tariffs (FIT) for biogas-derived electricity (0.49 CHF/kWh(el)). Thus, small-scale biogas installations are reviewed and the possibility to couple them with solid oxide fuel cells (SOFCs) and photovoltaic (PV) panels is analyzed. To date, less than 5% of the Swiss agricultural biogas potential is used. It is possible to increase this value significantly up to 86% through the deployment of 2 kW(el) engines. The small size of the Swiss farm requires biogas installations in the kW-range. Small-scale biogas facilities are not profitable yet: the main challenge is to bring down the lifetime cost of the fuel cells to 11,000 CHF/kW(el) (considering a lifetime of ten years) and to reduce the investment cost (IC) of small-scale biogas facilities to around 9500 CHF/kW(ch). In the kW-range, solid oxide fuel cells (SOFCs) have higher electrical conversion efficiencies than internal combustion engines (ICEs). It is shown that SOFCs become competitive over combustion engines if the investment cost of the former decreases below 13,000 CHF/kW(el) for a lifetime of 11 years. Combining the biogas facility with a PV-battery system, which covers the digester's electricity needs, is found to be beneficial. A considerable reduction in the feed-in tariffs would make small- to medium-scale biogas installations unprofitable, at current cost. In order to reach a break-even under these conditions, the investment cost of the biogas plant needs to drop below 4000 CHF/kW(ch), whereas the investment cost of the SOFC needs to drop below 3400 CHF/kW(el).

Dealing with fuel contaminants in biogas-fed solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) plants: Degradation of catalytic and electro-catalytic active surfaces and related gas purification methods

Hossein Madi, Davide Papurello, Jan Van Herle

Fuel cell and hydrogen technologies are re-gaining momentum in a number of sectors including industrial, tertiary and residential ones. Integrated biogas fuel cell plants in wastewater treatment plants and other bioenergy recovery plants are nowadays on the verge of becoming a clear opportunity for the market entry of high-temperature fuel cells in distributed generation (power production from a few kW to the MW scale). High-temperature fuel cell technologies like molten carbonate fuel cells (MCFCs) and solid oxide fuel cells (SOFCs) are especially fit to operate with carbon fuels due to their (direct or indirect) internal reforming capability. Especially, systems based on SOFC technology show the highest conversion efficiency of gaseous carbon fuels (e.g., natural gas, digester gas, and biomass-derived syngas) into electricity when compared to engines or gas turbines. Also, lower CO2 emissions and ultra-low emissions of atmospheric contaminants (SOx, CO, VOC, especially NOx) are generated per unit of electricity output. Nonetheless, stringent requirements apply regarding fuel purity. The presence of contaminants within the anode fuel stream, even at trace levels (sometimes ppb levels) can reduce the lifetime of key components like the fuel cell stack and reformer. In this work, we review the complex matrix (typology and amount) of different contaminants that is found in different biogas types (anaerobic digestion gas and landfill gas). We analyze the impact of contaminants on the fuel reformer and the SOFC stack to identify the threshold limits of the fuel cell system towards specific contaminants. Finally, technological solutions and related adsorbent materials to remove contaminants in a dedicated clean-up unit upstream of the fuel cell plant are also reviewed. (C) 2017 Elsevier Ltd. All rights reserved.

2017

Biogas as a fuel source for SOFC Cogenerators

Jan Van Herle

This study reports on the combination of solid oxide fuel cell (SOFC) generators fueled with biogas as renewable energy source, recoverable from wastes but at present underexploited. From a mobilisable near-future potential in the European Union (EU-15) of 17 Mtoe, under 15% appears to be converted today into useful heat and power (2 Mtoe). SOFCs could improve and promote the exploitation of biogas on manifold generation sites as small combined heat and power (5-50 kWel), especially for farm and sewage installations, raising the electrical conversion efficiency on such reduced and variable power level. Larger module packs of the high temperature ceramic converter would also be capable of operating on contaminated fuel of low heating value (less than 40% that natural gas) which can emanate from landfill sites (MW size). Landfill gas delivers 80% of current world biogas production. This document compiles and estimates biogas data on actual production and future potential and presents the thermodynamics of the biogas reforming and electrochemical conversion processes. A case study is reported of the energy balance of a small SOFC cogenerator operated with agricultural biogas, the largest potential source.

2004

A heat piloted 5 kW fuel cell

Sébastien Lerson, François Maréchal

Micro-cogeneration in residential applications is one of the efficient ways of improving the energy conversion efficiency in buildings. Cogeneration systems will cover electrical and thermal needs while reducing both energy bills and CO2 emissions. Thanks to its high efficiencies, SOFC (Solid Oxide Fuel Cell) seems to be one of the major emerging technologies in this field. The optimal design and operation of such a system will contribute to its profitability, a system analysis is therefore necessary. In a residential fuel cell installation project, the three following steps will be essential : Measurement or evaluation of thermal and electrical requirements profiles; Optimal system design and equipment rating; Optimal operation and control strategy of the heat/electricity management

2004

Hossein Madi, Davide Papurello, Jan Van Herle

2017