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The microchannel design process used by the researchers.
Wind power is not conditional, solar cells are too inefficient, and fuel generators are not environmentally friendly... If these energy sources do not meet your needs, a solid oxide fuel cell (SOFC) may be a good choice. According to the report of the Physicist Organization Network, the Pacific Northwest National Laboratory of the United States has recently developed a high-efficiency, small-scale solid oxide fuel cell with an energy conversion efficiency of 57% and its test system can generate 2 kilowatts of electricity. Family use. Coupled with its advantages of high efficiency and environmental protection, it is hoped that each company will have a "power station" to become a reality.
What is SOFC
Before understanding the solid oxide fuel cell, we need to know what the fuel cell is. From the appearance, the fuel cell looks like a battery, with a cathode, an anode, and an electrolyte. But the biggest difference between them is that the battery is an electrical storage device and the fuel cell is a power generation device that allows flammable fuel to react with oxygen to produce electricity. Therefore, as long as there is a continuous supply of fuel, the fuel cell will continuously produce electricity.
The biggest advantage of fuel cells is that they are highly efficient and environmentally friendly. At present, ordinary fuel generators can only convert 18% of the chemical energy into electric energy. If it is an automobile engine, the final conversion rate is less than 15%. In contrast, many fuel cells can achieve 30% to 50% conversion rate. High efficiency means that the fuel cell can produce the same amount of electricity as a conventional power plant with less fuel and less pollution.
Solid oxide fuel cells are a new generation of fuel cells that can directly convert the chemical energy stored in fuels and oxidants into electrical energy at high temperatures. No matter it is oxygen, biogas, hydrogen, diesel or gasoline, it can be used as fuel for power generation. Compared with other fuel cells, solid oxide fuel cells also have the advantages of wide fuel adaptability, high energy conversion efficiency, all solid state, modular assembly, and zero pollution.
Focus on small to focus on the big
Solid oxide fuel cells are a promising technology that can provide clean and efficient energy. So far, most people have focused their attention on the research of larger systems that can generate 1 MW or more of electricity and can replace conventional power stations, with a view to producing breakthrough results. Why do scientists at the Pacific Northwest National Laboratory have to go their own way and focus on the development of small systems?
Vincent Sprink, chief engineer of the laboratory's solid oxide fuel cell project, explained: “Because small systems also have advantages, sometimes even better than large systems.†Home and community users are such an example: If When large-scale systems are installed, the electricity generated by them will exceed the power consumption of the nearby areas, so that they must be transported to other places via transmission lines. This process will inevitably cause some power loss. On the other hand, the small system is more lightweight and flexible, the installation location can be closer to the user, the delivery costs and losses will be lower, and if necessary, it can be integrated to form a larger system.
For this reason, scientists have put forward an idea that this small-scale power generation system must not only exceed 50% in efficiency but also be able to easily expand distributed generation when needed.
Two innovations solve puzzles
In order to achieve this goal, allowing small systems to produce efficiencies that are close to or even higher than large systems, the researchers used two processes called microchannels and fuel cycles.
The solid oxide fuel cell is made of ceramic material and is divided into three levels: positive electrode, negative electrode, and electrolyte. During operation, the compressed air is first pumped into the outer layer as a negative electrode, and the oxygen in the air becomes a negatively charged superoxide anion. The negative electrode then contacts the internal electrolyte layer and oxygen ions pass through the electrolyte to the positive electrode layer, where the oxygen ions react with the fuel to produce electricity and by-product vapors and carbon dioxide.
However, the previous method was to directly expose the steam to the fuel cell, which would cause the ceramic layer in the fuel cell to be heated unevenly or even be damaged. In the new study, scientists used a micro-channel technology to allow the steam to complete the initial reaction with the fuel cell from the outside, not only reducing the damage of the battery, but also increasing the surface area of ​​the reaction and improving the reaction efficiency. Through this technology, waste heat and exhaust gas during the reaction can be reused, further reducing fuel consumption.
Experiments show that the optimized system's efficiency at 2.2 kWh and 1.7 kWh can reach 48.2% and 56.6%, respectively. The research team expects that with only a few minor adjustments, they can also increase system efficiency to 60%. This is not only higher than the 15% efficiency of the internal combustion engine, but also much higher than the efficiency of other fuel cells of the same volume of 30% to 50%. The single test system they produced could already produce 2 kilowatts of electricity, which is roughly equivalent to the power consumption of a typical American home. After the expansion, the system can also be upgraded to between 100 and 250 kilowatts, to meet the electricity needs of 50 to 100 American homes.
Spreek is very satisfied with this result. He said: "While the cost of this small solid oxide fuel cell is relatively high, it is currently not yet widely available. However, this work has confirmed the feasibility of this technology, which shows that the increase in power generation while reducing carbon dioxide emissions and Not wishful thinking.†He hopes the technology will be available as soon as possible in a single home or company. (Reporter Wang Xiaolong’s comprehensive foreign news)
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