Click here to access the full article published in International Journal of Hydrogen Energy.
A previous work related to the above study has been published in Scientific Reports:
|Figure 1. Share of energy sources in Nepal: (a) contribution in total consumption; (b) breakdown of traditional sources; (c) breakdown of commercial sources.|
AFCs are widely known for space applications since their first use in NASA’s Apollo program in 1965. However, terrestrial applications of AFCs seem too costly due to the strict requirement of CO2-free fuel and oxidant. As a result, R&D work on AFCs has gone down in recent years.
PAFC represents the first fuel cell technology that was developed commercially and is still the only commercially available one. Over 250 units of PC-25, a 200 kW PAFC system developed by UTC Fuel Cells, are reported to have been sold and installed in different countries around the world since the early 1990s. Despite the success PAFCs achieved, interest in them started declining in the late 1990s mainly owing to their high cost coupled with insufficient operating reliability in the long-term.
With the availability of more stable proton exchange membranes such as Nafion (1960s) and the development of modern membrane electrode assembly (MEA) with reduced catalyst loadings (mid-1980s), PEFC technology has become potentially attractive especially for automotive applications. However, further reduction in system cost (such as the development of non-platinum catalysts and cheaper membranes) as well as improvement in long-term performance (mainly CO tolerance) is imperative in order to penetrate the markets.
MCFCs, one of the earliest fuel cells used in practical applications, are preferred for natural gas and coal-based power plants. However, poor long-term reliability has been the major hindrance to their commercialization, which is associated with the issues such as gradual dissolution of nickel oxide from the cathode, anode creep and corrosion of metal parts. Consequently, research and engineering work on MCFCs has gradually shrunk since the early 2000s and the interest of developers has shifted to another high temperature fuel cell, SOFC.
Elimination of electrolyte management problems, fuel flexibility and high electrical efficiencies have all made SOFC an attractive emerging technology for future power generation, especially in stationary applications. Though most of the benefits of SOFCs result from their high temperature operation, cost and durability issues associated with such high temperatures are yet to be solved. Therefore, current research on SOFCs in academia, industry and governmental laboratories is primarily focused on developing intermediate temperature SOFCs (IT-SOFCs) (operating at < 700 deg. C) which allow the use of low cost materials with improved durability and offer the same advantages as the conventional SOFCs do.
Despite their low efficiency, DMFCs are expected to find their applications in consumer electronic products such as mobile phones, digital cameras and laptop computers in which energy density, compactness in design and convenience of refilling the fuel are of prime concern. To make DMFCs competitive with state-of-the-art lithium-ion batteries in consumer electronics, current research is focused on finding suitable electrolyte materials so as to minimize the fuel crossover problem and developing more active anode catalysts to enhance methanol oxidation.
Process flow diagram of the Nakoso IGCC plant