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This review presents methanol as a potential renewable alternative to fossil fuels in the fight against climate change. It explores the renewable ways of obtaining methanol and its use in efficient energy systems for a net zero-emission carbon cycle, with a special focus on fuel cells. It investigates the different parts of the carbon cycle from a methanol and fuel cell perspective. In recent years, the potential for a methanol economy has been shown and there has been significant technological advancement of its renewable production and utilization. Even though its full adoption will require further development, it can be produced from renewable electricity and biomass or CO2 capture and can be used in several industrial sectors, which make it an excellent liquid electrofuel for the transition to a sustainable economy. By converting CO2 into liquid fuels, the harmful effects of CO2 emissions from existing industries that still rely on fossil fuels are reduced. The methanol can then be used both in the energy sector and the chemical industry, and become an all-around substitute for petroleum. The scope of this review is to put together the different aspects of methanol as an energy carrier of the future, with particular focus on its renewable production and its use in high-temperature polymer electrolyte fuel cells (HT-PEMFCs) via methanol steam reforming.

In this paper, a simplified model of a Polymer Electrolyte Membrane (PEM) water electrolysis cell is presented and compared with experimental data at 60 °C and 80 °C. The model utilizes the same modelling approach used in previous work where the electrolyzer cell is divided in four subsections: cathode, anode, membrane and voltage. The model of the electrodes includes key electrochemical reactions and gas transport mechanism (i.e., H2, O2 and H2O) whereas the model of the membrane includes physical mechanisms such as water diffusion, electro osmotic drag and hydraulic pressure. Voltage was modelled including main overpotentials (i.e., activation, ohmic, concentration). First and second law efficiencies were defined. Key empirical parameters depending on temperature were identified in the activation and ohmic overpotentials. The electrodes reference exchange current densities and change transfer coefficients were related to activation overpotentials whereas hydrogen ion diffusion to Ohmic overvoltages. These model parameters were empirically fitted so that polarization curve obtained by the model predicted well the voltage at different current found by the experimental results. Finally, from the efficiency calculation, it was shown that at low current densities the electrolyzer cell absorbs heat from the surroundings. The model is not able to describe the transients involved during the cell electrochemical reactions, however these processes are assumed relatively fast. For this reason, the model can be implemented in system dynamic modelling for hydrogen production and storage where components dynamic is generally slower compared to the cell electrochemical reactions dynamics.

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Early version, also known as pre-print Link to publication from Aalborg University Citation for published version (APA):Yang, W., Zhao, Y., Liso, V., & Brandon, N. (2014). Optimal design and operation of a syngas-fuelled SOFC micro CHP system for residential applications in different climate zones in China. Energy and Buildings, 80, 613-622. https://doi.org/10.1016/j.enbuild.2014.05.015 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.? Users may download and print one copy of any publication from the public portal for the purpose of private study or research. ? You may not further distribute the material or use it for any profit-making activity or commercial gain ? You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access to the work immediately and investigate your claim. t r a c tFuel cell based micro-CHP systems are expected to be one of the most promising technologies for implementation in the residential sector. Since the design and operation of such CHP systems are greatly dependent upon the seasonal atmospheric conditions, it is important to evaluate their performance under difference climate conditions to ensure that it is well matched with the local heat-to-power ratio. The aim of this study is to investigate the optimal design and operation of a syngas-fuelled SOFC micro-CHP system for small households located in five different climate zones in China. The ability of the micro-CHP to cover the heat and electricity demand of a 70 m 2 single-family apartment with an average number of occupants of 3 is evaluated. A detailed model of the micro-CHP unit coupled with a hot water storage tank and an auxiliary boiler is developed. System design trade-offs are discussed to determine the optimal match between the energy demand of the household for different climates across China and the energy supply of the micro-CHP during the whole year. Moreover, criteria for sizing the system components of the micro-CHP are specifically addressed. The developed methodology can be applied to different types of residence with different load profiles.