source link Hydrogen-powered fuel cells are also far more energy efficient than traditional combustion technologies. The biggest hurdle for fuel cells today is cost.
Fuel cells cannot yet compete economically with more traditional energy technologies, though rapid technical advances are being made. Although hydrogen is the most abundant element in the universe, it is difficult to store and distribute. Canisters of pure hydrogen are readily available from hydrogen producers, but as of now, you can't just fill up with hydrogen at a local gas station. Many people do have access to natural gas or propane tanks at their houses, however, so it is likely that these fuels will be used to power future home fuel cells.
Methanol, a liquid fuel, is easily transportable, like gasoline, and could be used in automobile fuel cells. However, also like gasoline, methanol produces polluting carbon dioxide. Read Caption. A5T1ED a zinc based metal fuel cell.
A large amount of inert solids are used as the heat carrier circulating in the three beds to provide heat efficiently from the combustor to the pyrolyzer and char gasifier. The system is mainly composed of a steam gasifier and a SOFC, in which the heat and steam generated in the SOFC are fed directly to the steam gasifier.
Other hybrid power generation systems, such as integrating catalytic gasification, SOFC, oxygen transfer membrane OTM and gas turbine [ 40 ] or integrating coal gasification, SOFC, and chemical looping combustion CLC processes [ 41 ], also achieved high energy efficiency.
Retrofitting existing IGCC power plants with SOFC and CO 2 capture has been simulated and results indicate significant thermodynamic advantages in terms of boosting electrical and exergy efficiencies [ 42 ]. A direct carbon fuel cell DCFC is a device that generates electricity through the direct electrochemical oxidation of solid carbon to CO 2 see Fig.
A DCFC has a single process chamber for solid fuel conversion contacting the anode. Attempts to use solid carbon to generate electricity date back more than a century to the demonstration of the first molten hydroxide DCFC proposed by William Jacques in Useful reviews of devices tested in the early years of development were conducted by Howard in and Liebhafsky and others in However, it was the DCFC demonstration at Stanford Research Institute in the s that renewed interest in the direct electrochemical oxidation of solid carbon [ 5 , 45 ].
Schematic of a coal-fuelled DCFC power generation system [ 46 ]. The by-product is highly concentrated CO 2 requiring no gas separation that can be directly stored, avoiding cost and efficiency penalties.
There is no need for water usage in the process, an advantage over the IGFC concept. Despite the advantages, the development of DCFC technology is still in its infancy. Carbon derived from cheap sources, like coal, can have a high electrical conductivity and when pressed directly onto the solid electrolyte offers the shortest distance possible for mass transport from the anode to the electrolyte.
However, refuelling the anode still has technical issues and only conductive forms of carbon can be used, which excludes raw coal. Coal processing can add cost. DCFC technology also has to overcome other challenges before becoming commercially viable, such as poor power density, high degradation rates, fuel feed system, scaling up the technology and fuel processing procedures.
Current efforts are broadly focused on material selection for critical fuel cell components and understanding reaction mechanisms for carbon oxidation. Research relevant to coal includes the effect of coal properties and pretreatment on DCFC performance and some DCFC operational tests with coal as the fuel, which are described below. Almost all types of coal have been tested in DCFCs. The effects of the physical and chemical properties of coal, and the coal preparation methods on DCFC performance, have been studied.
The results revealed that the DCFC performance is affected by coal properties, such as volatile matter, oxygen content and structure disorder. High coal reactivity enhances cell performance whereas high ash and sulphur content reduces it. The best DCFC performance was obtained with bituminous coal, due to its high volatile matter and low sulphur content. Many coals are treated to remove impurities and to recover volatiles before use in fuel cells, which have improved the cell performance [ 47—55 ]. Performance of DCFC with different electrolytes has been studied.
Coal-derived carbon anode, iron—titanium alloy cathode and humidified air as the oxidant are used for DCFC. For direct carbon molten carbonate fuel cells DC-MCFCs , solid carbon fuel is directly fed into the anode chamber where it is oxidized. However, the technology was licensed to Contained Energy, and no further progress is reported [ 57 ]. Eom and others [ 58 ] achieved maximum power density of Although DC-MCFC is arguably one of the most well understood DCFC designs and most suited for large-scale power plants, it appears that there is currently little commercial interest in the further development of this technology [ 5 , 56 ].
The most advanced direct carbon solid oxide fuel cell DC-SOFC technologies are through carbon placed within the anode chamber and use gasification. Akron University proposed a design using YSZ electrolyte button cells and coal as the fuel for stationary power generation see Fig. Raw or devolatilized coal is placed within the anode chamber in direct contact with the cell. Nickel, copper and gold-based materials and lanthanum strontium manganite LSM are used for anode and cathode catalysts, respectively. It has been claimed that a build-up of ash on the anode surface decreases the power density, but on removal of ash, the power density is restored to its previous values.
It was found that the limited oxygen ion diffusion across the electrolyte membrane and the long-term activity of the anode catalyst are the main issues affecting performance [ 5 ]. Schematic design of a coal-fuelled DCFC for stationary power generation [ 5 ]. An integrated external to the fuel cell stack gasifier and fuel cell system, which operates on gas derived from coal, cannot be strictly described as a direct carbon fuel cell. However, due to the close proximity of the gasifier and fuel cell, which leads to both thermal and gas phase coupling, this design is still considered as DCFC.
This approach differs from an IGFC system as it electrochemically converts coal to electricity based on dry gasification using anode recycle of the product gas CO 2 see Fig. Different carbon fuels, such as coals, coal chars, graphite, activated carbons, biochar and commercial carbon blacks, were studied for in situ gasification and DCFC. So far, cells have operated for only up to h [ 56 ] and more research is required on this technology.
Schematic design of an integrated dry coal gasification SOFC system [ 59 ]. In this configuration see Fig.
The fuel goes into a SOFC disc near top in the same chamber, where it reacts with oxygen from the air blue arrows to produce electricity. Possible configuration for the coal gasification and SOFC system [ 60 ]. The cell feeds carbon directly to the electrolyte surface using molten carbonate.
Deleebeeck and others [ 45 , 48 ] at the Danish Technical University have joined the work on this topic recently. SRI International demonstrated a six-cell stack constructed from six YSZ tubular cells immersed in a single molten carbonate bath containing solid carbon fuel. SRI International also operated a similar design cell in excess of h [ 5 , 56 ]. The cell with bituminous and anthracite coal showed good durability over two hours of testing compared to the lignite coal. The total power output from anthracite coal was higher than that from the bituminous coal.
They found that pyrolysis in air of demineralized anthracite coal samples and utilization of a cathode-supported SOFC architecture enhanced cell performance. Cathode-supported cells resulted in higher power densities than the carbon black-fuelled anode-supported counterpart [ 61—63 ]. Coal-fuelled stationary fuel cells are still at an early stage of development. Natural gas- and hydrogen-fuelled small- and medium-sized systems are commercially available and could switch fuel when the hydrogen from coal technology is sufficiently advanced.
For large IGFC power generation systems, experimental tests, even at the laboratory scale, are scarce due to the high cost. Most of the academic research is at a theoretical level of plant configurations, concept design and economical modelling analysis. DCFC technology is still at the concept validation stage. Current efforts are focused on materials selection and understanding reaction mechanisms.
It is estimated that, by the year , the cost of fuel cells will be competitive with. ICEs based on the technological improvements being made. Find composite data products (CDP) and publications about NREL's analysis of fuel cell technology status with a focus on performance, degradation, and.
The overall challenges for stationary fuel cells are the cost and cell durability. For the IGFC system, the gas cleaning process adds another energy barrier to its power generation. For DCFCs, coal fuel contamination and low power density are the main issues to overcome. Until now, stationary fuel cells have been manufactured at very low volumes and further investment is required in the development of large scale manufacturing technology. Further development of electrode materials, catalysts, membranes and electrolytes are critical for improving cell performance and commercial viability.
Reducing the cost of manufacture can benefit all aspects of fuel cell systems, including hydrogen production and storage systems, and hydrogen infrastructure. Support from governments is critical to progress stationary fuel cell applications until they are ready to enter the market.
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Close mobile search navigation Article Navigation. Volume 2. Article Contents. Current status of stationary fuel cells for coal power generation Xing Zhang. Corresponding author. E-mail: xing. Oxford Academic. Google Scholar. Cite Citation.
Permissions Icon Permissions. Abstract Fuel cells electrochemically convert chemical energy in fuels into electrical energy and heat and so can produce power efficiently with low environmental impact. Open in new tab Download slide. Table 1. Open in new tab. Google Preview. Fuel cell technologies, applications, and state of the art.
A reference guide. July Mukhtar Bello. Cited by. Related Articles. Paper Title Pages. Authors: Thanganathan Uma, Masayuki Nogami. The performance of the electrode was evaluated by the measurement of cell potential-current density plots. While the polarization curve yields data related to basic cell performance, more detailed information can be found by electrochemical measurements with an impedance analyzer. The power density shows a similar pattern to current density. The maximum power density value of The glass membrane here plays a key role as electrolyte medium for proton transport and barrier to avoid the direct contact between fuel and oxygen.
Abstract: National Research Council NRC as the premier research and development organization within the government of Canada has the mandate of providing vital scientific and technological services to research and industrial communities. Abstract: This paper experimentally investigates the dynamic response of a single fuel cell under various dynamic loadings with different operating conditions.
The operating conditions are set at different cell temperatures, humidification temperatures, and stoichiometric rates during each test to study the effects of these parameters on the cell performance of a PEM fuel cell. Abstract: During the average fifty or sixty years of building lifecycles, large amounts of energies are consumed at all stages, from the production of building materials, transportation for project constructions, daily use, and maintenance to demolition, in particular, the daily energy consumption of air-conditioners, lighting, and elevators.
The main evaluation items are building envelope heating load ratio, air-conditioner energy efficiency ratio, and lighting energy saving ratio. During evaluation, the promotion and application of renewable energy is encouraged by incentive factors. The development and use of renewable energy technology may improve energy utilization efficiency, maintain a balance of supply and demand, and reduce environmental pollution, thus, this study developed a indoor personal office system with 1KW solar energy and a W proton exchange membrane fuel cell PEM fuel cell as the power source, which is composed of LED indoor lighting, air fan, LED table lamp, notebook computer, printer, and acoustic equipment.
Under continuous operations of 24h, this office system will generate 12kwh of electricity, which reduces 7. If continuously operated for 1 year, it will generate 4,kwh electricity, which reduces 2,