Solid oxide fuels cells are being developed as the main source of energy. Several researches have been undertaken in the project. There is substantial progress, but, this endeavor faces challenges and problems. The research has been extremely involving and demanding. This is due to the environmentalists and engineers, who want to get the benefits of a clean electric power of the heavy batteries or the engines that do not cause any pollution. This has led to an investment in the wind farms and solar panels as the alternative energy. They can be effective and efficient sources of electric energy, but there are issues with their stability, as energy sources. For example, during rainy, windless or cloudy days these sources can fail. In addition, the applications of these sources are limited due to the lack of portability. The solar panel is incapable of giving light at night, just as the windmill does not give much help to a power plant that is using diesel. This is what has given a rise to investments in the solid oxide fuel cells.
The challenges of alternative sources of energy have led to energy research revolution. The revolution started back in 1962, when scientists of Siemens Westinghouse (formerly, Westinghouse Electric Corporation) did a feasibility study of getting electricity form a piece of equipment that was called “solid electrolyte fuel cell’. Hence forth more developments and researches to develop the alternative source of energy, using a technology called fuel cells, have taken place. Biello (2009) notes, this has made the fuel cell technology the main event. In addition, the technology is on the verge of developing into a large-scale commercial achievement and use. The fuel-cell technology is no longer in the development and experimental research, but, rather they have become a reality. The plants for the large-scale production for the systems have already been built. These plants have already shown lower use of the natural fuels of the unit generated power. In addition, there is lower emission of harmful products and greenhouse gases. Most of these developments are, however, financed and initiated by the government. Moreover, the current medium-sized power plants for electric vehicles based on the fuel cells are sponsored by the government of different nations.
The SOFC has been there for a long time and has been used by the NASA since 1960s. The fuels have not gained the widespread use because of the high costs. Other fuel technologies that are being used such as; phosphoric acid fuels (PAFCs), molten carbonate fuel cells (MCFCs), and proton exchange membranes (PEMs), have all along required corrosive acids, expensive and valuable metals, to contain the molten materials. In addition, the performances of these alternative energy sources have been marginal. They have not been able to provide the strong energy, in terms of the economic value intention to surmount the problem that exists. This has led to a research to overcome the limitations, by making use of fuel cell technology. It led to an offer of the combined heat and power (CHP) methods to utilize the heat that is being wasted. However, the CHP does not improve the economic value benefit that is expected. It only helps in the environment with the exact ratios of power and heat requirements on a daily basis. Totally, the customization, complexity, and cost of CHP, seems to prevail over the benefits.
The events have made experts agree that solid oxide fuel cells (SOFCs), has the best prospective form of fuel cell technology. Using high electrical efficiencies, and low cost ceramic materials, the SOFCs can be a better economic alternative than CHP. However, this is not that effortless as there are considerable technical challenges that are inhibiting the commercialization of the fuel cell technology. These challenges include the use of exceptionally high temperatures of around 800 degrees centigrade by SOFCs when in operation. According to Eguchi (2007), the high temperatures, thus; give SOFCs fuel flexibility and high electrical efficiencies that both help in terms of economy. However, this is a challenge to engineering. These challenges are being addressed and solved.
The development of the field is market driven, and commercial production has led to challenges. The applications in civil areas are a challenge as the government is not involved in small-size fuel-cell development of the power plants. The broader utilization of fuel power plants has a problem in terms of costs. To make use of the new types of manageable electronic devices and the prospective multimillion-dollar markets of electric vehicles, these problems have to be addressed. The manufacturing cost of the fuel-cell power plants at the moment is very high. This is when compared to the other types of power plants. The high cost is not only because of high labor costs, that can be, highly reduced when there are increased high volume productions, but, the high cost of materials too. The components of the fuel cells are expensive. For example, the Nafion® membrane, which is a, significant component of direct-methanol and proton-exchange membrane is quite expensive. It goes for about 700 $/m2 which is very expensive.
The prices of the platinum catalysts are considerably expensive, despite, the recent strong decline in the quantity of platinum used in the fuel cell electrodes. According to Bagotsky (2009), it costs 1200 $/kW, for a 5 kW proton-exchange-membrane fuel-cell power plant. In addition, it costs 500 $/kW for the concrete fuel stack membrane, with 55 $/kW. The platinum costs 52 $/kW, while the ancillary equipments like the heat exchanges and pumps costs 700 $/kW. This is in comparison to 500-1500 $/kW, that a similar internal combustion engine costs. Therefore, for future commercialization and mass production of the fuel-cell-powered electric cars, a further diminution of the manufacturing costs is required.
The other challenge faced by the SOFCs is the problem of lifetime. The application of fuel cell plants needs a lifetime that is satisfactory. This is needed for the smooth operation in any of the modes that exist. The lifetime of the portable devices that are used in small plants should be around three years. The electric vehicles should have around five years, whereas, it has to be about ten years, for the large immobile, multi-megawatt power plants. The fuel stacks and single proton exchange membrane fuel cells samples have operated successfully many hours. These indicate that the proton exchange membrane fuel call can operate for many years when in application. The problem is the use of the fuel type does not have enough data for reference. This has made a further research be undertaken to find the reasons for the premature failure, and decline in efficiency of the types of fuel cells.
The fuel cells are electromagnetic devices that convert the chemical energy that is found in fuels such as; methane, diesel, hydrogen, gasoline, and butane, into electrical energy. This is done by exploiting the advantage of the reaction between hydrogen and oxygen. Therefore, this involves controlling the reaction through a device and harvesting the energy that is produced. The fuel cells are simple devices that do not have movable parts, and consist of four functional constituent elements namely; anode, cathode, electrolyte, and interconnect. Developers and researchers have focused on the solid oxide fuel cells (SOFC). The reason behind is that they can convert an extensive multiplicity of fuels. Furthermore, they have a high efficiency rate of about 40-60% when unassisted, and around 70% when pressurized compared to other power plants like modern thermal engines that are 30-40% efficient. These advantages have made the solid oxide fuel cells dominate over other fuel cells (Singh 2007).
Moreover, the ability of the SOFCs to use the fossil fuels that are currently available makes the operating costs to be abridged. This is better in contrast, to the other fuel cells technologies, such as phosphoric acid, polymer electrolyte, alkali, and molten carbonate, which require hydrogen as the main source of fuel. In addition, other advantages that make SOFCs an interesting source of energy are; their reliability, cleanliness, and non-polluting nature. Due to the non-moving parts, the cells are vibration free, and it eliminates noise pollution linked with power generation.
The challenges of SOFC technology are being addressed and solved by numerous researches. The engineering challenges that pose the greatest threat to SOFC usage is being solved by various researchers, who are taking place in the breakthrough. There has been some breakthrough in the material science. The revolution of new designs has been done by Bloom’s SOFC technology. This all- electric solution is at the same time cost effective. The further research in technology has led to making fuels more affordable, reliable, and clean. The SOFCs are developed by means of inexpensive electrodes and solid electrolyte. The fuels generate electricity by minimal pollution. It’s only by product which is water, is the combination of oxygen and hydrogen that generate electricity.
Building an inexpensive, reliable, and efficient fuel cell is challenging. Investors and scientists have made attempts to design fuel cells that can solve these issues. This is done to create a greater efficiency. Many varieties, design sizes and types with different technical details have been developed. Li (2009) says the problem is that the developers are constrained by the choice of the electrolyte for this purpose. For example, the electrodes design and material for their manufacture depend on the electrolyte. The leading electrolyte types available include; phosphoric acid, solid oxide, molten carbonate, proton exchange membrane (PEM), and alkali. These include both the solid and liquid types. Another hindrance is that the type of fuel also relies on the electrolyte, despite the fact that some forms of cells require pure hydrogen. Then it calls for an extra demand of the equipment like “reformer” to decontaminate the fuel. While, other cells tolerate some impurities, they need higher temperatures to run powerfully. In addition, the liquid electrolytes flow in some cells, hence, requires pumps. Moreover, the electrolyte type dictates the temperature operation like “molten” carbonate cells, which run while being hot, as the name suggests. The types of fuel cells have their own advantages and disadvantages. So far none of the fuels is efficient enough and cheap to replace the traditional way of power generation, such as; hydroelectric, coal-fired and nuclear power plants.
The Northwestern University did research the solid oxide electrolyte. They found that SOFCs use ceramic compound of metals such as zirconium or calcium that are hard and oxides, which are chemically combined and have oxygen, as electrolyte. They got results that indicated that, the electrolytes are normally CaO or ZrO and operate at high temperatures of 1000 °C. In addition, the output is around 100 kW and the operation efficiency of the electrolyte is around 60%. The high temperatures make the reformer require the extraction of hydrogen from the fuel. In addition, the waste heat can be used to produce more electricity. The high temperature, however, is what limits the applications of SOFC. At the same time, the solid electrolytes cannot leak, but they can crack. The research on the scalability, minimization of electrical losses, manufacturability, and having tight gas seals were held to prevent oxidation and the SOFC fuel mixing. In addition, the researchers tried to optimize the mechanical strength and electrical performance simultaneously.
The researchers also tried to develop high quality mechanical properties. This involved the use of high resistance materials, use of porous supports, flattened tubes that are geometrically easy to process. The use of small size cells was introduced to minimize the electrode current paths and resistance loss. According to Bove (2009), this helped in eliminating the high resistance pressure contacts between the IC and SOFA plates that were used in the experiment. The researchers found that since the plates were not in contact, the manufacturing tolerances reduced. The current flowed along the surface instead of between the pieces. This was done in the flattened tubes that allowed for high volume density, while at the same time minimizing sealing problems. In addition, interconnects were eliminated, and the number of flow fields was reduced in relation to the planar SOFC.
SOFCs have been operating at temperatures ranging from 900 to 1000oC (1692 to 1832oF). The reforming of the hydrocarbon fuels and the capability of the high temperatures gives it high quality. The high temperatures have been used for cogeneration, and they can be used in the gas turbines, to increase the efficiency, when pressurized. The reduction of the high temperature by about 200oC (392oF) gives the allowance of more materials use. It gives a balance of components, aids in faster cooling, simplifies the thermal management. This in turn, results in less degradation of the stack and cell components. The SOFCs ability in operating at 650 to 800oC (1202 to 1472oF) temperatures has led to new developments in these years. The lower temperatures, however, make the electrode kinetics, and electrolyte conductivity to decrease significantly. This has led to researches in alternative designs and cell materials in order to beat these challenges. The materials of the cell component should have the best electrical conductivity properties. This is needed for the components, to perform at their best expected cell functions. In addition, adequate structural and chemical stability encounters at high temperature during the cell fabrication and operation. This leads to minimal inner diffusion and reactivity in the components that make SOFC. Therefore, it is difficult to match the thermal expansion in the components that are different.
The Bloom Energy unveiled a fuel system that runs on an assortment of fuels. Furthermore, the fuels pay through a lower energy bill in three to five years of usage. The technology, according to Bullis (2010), when powered by the natural gas it cuts the carbon dioxide that is emitted by half compared to the predictable power sources emission. The use of the fuels by several companies within months indicates a generation of 11 kW/h of electricity. This power is able to serve about 1,000 homes with electricity for a year. In addition, the costs of electricity are lower compared to buying them from the grid. This is because the electricity is generated on site, and the fuels are proficient. This leads to avoidance of a grid in electricity distribution. The SOFCs operate at high temperatures of over 600 ºC, which makes it possible to run on a number of fuels. In addition, this makes SOFCs efficient for electricity generation than the conventional turbines. However, their reliability and high cost challenges has limited the large scale commercial use. Although, Bloom’s technology has tried to make the fuel cells affordable, more is expected on reduction of costs as production and use increases. They have the 100 kW modules for sale. This is made flat 25 W and small fuel cells that are stack together. The complete 100 kW modules have multiple stacks, which have converting DC power equipment. This is for converting the DC power from the AC power that is used in the buildings. The equipment is the size of a parking place and can be used in small power houses like supermarkets. The fuels cells can also be run in annul, to produce fuel by pimping in electricity.