Emission and economic performance assessment of a solid oxide fuel cell micro-combined heat and power system in a domestic building

Abstract

Saffa (2015) Emission and economic performance assessment of a solid oxide fuel cell microcombined heat and power system in a domestic building. Applied Thermal Engineering, 90 . pp. 1082-1089. ISSN 1873 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/33102/1/REVISION%20ATE-2014-7542.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the Creative Commons Attribution Non-commercial No Derivatives licence and may be reused according to the conditions of the licence. For more details see: http://creativecommons.org/licenses/by-nc-nd/2.5/ A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. This paper aims to assess the emission and economic performance of a commercially available solid oxide fuel cell (SOFC) mCHP system, operating at The University of Nottingham's Creative Energy Homes. The performance assessment evaluates, over a one year period, the associated carbon (emission assessment) and operational costs (economic assessment) of the SOFC mCHP case compared to a 'base case' of grid electricity and a highly efficient gas boiler.Results from the annual assessment show that that the SOFC mCHP system can generate annual emission reductions of up to 56% and cost reductions of 177% compared to the base case scenario. However support mechanisms such as; electrical export, feed in tariff and export tariff, are required in order to achieve this, the results are significantly less without. A net present value (NPV) analysis shows that the base case is still more profitable over a 15 year period, even though the SOFC mCHP system generates annual revenue; this is on account of the SOFC's high capital cost. In summary, grid interaction and incubator support is essential for significant annual emission and cost reductions compared to a grid electricity and gas boiler scenario. Currently capital cost is the greatest barrier to the economic viability of the system. KEYWORDS:Solid oxide fuel cell, micro-combined heat and power, domestic, emission, economic NOMENCLATURE Abbreviations CCGT = combined cycle gas turbine CHP = combined heat and power DB = DesignBuilder DEG = Decentralised energy generation DHW = domestic hot water H:P = Heat to power demand ratio mCHP = micro-combined heat and power PEMFC = proton exchange fuel cell SE = Stirling engine SOFC = solid oxide fuel cell SPBP = simple payback period Parameters and variables E d = Electrical demand (kWh) E SOFC = SOFC electrical output (kWh) E im = Imported electricity (kWh) E ex = Exported electricity (kWh) Q d = Thermal demand (kWh) Q SOFC = SOFC thermal output (kWh) α E = Electricity cost (£ / kWh) α NG...

Transition Cycles during Operation of a Reversible Solid Oxide Electrolyzer/Fuel Cell (rSOC) System

“…In this case, some H 2 was first added to the inlet in order to ramp up the current to its target value. Finally, the added H 2 was gradually removed and replaced with additional CH 4 and H 2 O. Some voltage instabilities were recorded due to the steam supply, and their amplitude decreased with higher steam flowrate.…”

“…As a consequence, the stack OCV is only seen increasing up 28 V over 7 min, and the stack voltage is seen increasing over the first few minutes of fuel cell operation (>14 min in Figure 4, right). Figure 5 illustrates the transition from SOFC-H 2 mode to SOFC-CH 4 , done under constant current to prevent thermal shocking the stack. Indeed, the exothermicity of the electrochemical reaction of H 2 oxidation was used to compensate for the strong heat demand of the methane steam reforming reaction.…”

“…While market penetration of small scale solid oxide fuel cell systems accelerates , efforts are being devoted to increasing stacking and reaching higher efficiencies in SOFC systems through the implementation of recirculation loops . On the electrolysis side, tremendous progress has recently been achieved in demonstrating commercially viable lifetimes and scaling up SOEC technology .…”

“…While market penetration of small scale solid oxide fuel cell systems accelerates [3][4][5], efforts are being devoted to increasing stacking [6] and reaching higher efficiencies in SOFC systems through the implementation of recirculation loops [7][8][9].…”

Status on Demonstration of Fuel Cell Based Micro‐CHP Units in Europe

“…For micro‐CHP applications, two main types of fuel cells are used: solid oxide fuel cells (SOFC), which operate at high temperatures (600–850 °C) and are made from ceramic materials (“solid oxide”) and polymer electrolyte membrane (PEM) fuel cells which operate at lower temperatures (60–160 °C) and are based on polymer materials. Fuel cell micro‐CHP units allow for significant increases in the efficiency of heat and power production compared with traditional heating appliances, eliminate the transmission losses of grid distributed electricity and, hence, they may bring a reduction in the overall primary energy consumption of the households .…”