Today human kind is still striving (and struggling) to solve the problem of how to make a device that can produce electricity easily and efficiently but that people will buy. Thus, our research group is primarily studying ways to improve the materials that make up batteries, fuel cells, and other energy efficient devices. Most people are very familiar with batteries, as they use them in everyday life such as cell phones and lap tops. However, would it not be nice to have a battery that could last 24 hours rather than the 2 or 3 hours? Well, fuel cells may be the answer to this.
We are looking at small fuel cells, which in effect work just like a battery except they run off of a fuel such as hydrogen, propane, or natural gas, producing electricity and by-products (just water in the case of hydrogen). As they are based on ceramic materials (ceramic oxides) and are all solid state materials, they are called solid oxide fuel cells (SOFC). Typical thermal reactions “burn” the fuel to produce heat, light and products; the thermal energy is then used to drive a turbine, or a similar mechanical device, to produce electricity. In a fuel cell the fuel is electrochemically converted to the same products, but rather than producing the energy as heat and light, it produces electricity directly via an electrochemical reaction. Thus, these devices are much more energy efficient, as they do not have to convert the heat from the reaction to mechanical work and then to electricity. They also do not “run out” like a battery (which of course needs to be recharged), as they work continuously provided there is fuel available, and most small cartridges (about the size of a laptop battery) should last more than 24 hours.
Our fuel cells are basically small, air-tight tubes with fuel running through the tube. The reaction, therefore, occurs inside the small tubes. The tubes are stacked into bundles to produce enough power to run the device of interest.
However there are a lot of hurdles to their commercialization, such as cost and longevity of the materials. One of the biggest issues is that using hydrocarbon fuels more efficiently can result in the formation of soot (or carbon) coking up the system. Thus, we are looking at materials for the anode (the side of the fuel cell where the oxidation of the fuel takes place) that are resistant to coking. We are also looking at different designs of fuel cells.
In addition to micro fuel cells, we are studying large scale systems for homes and apartments, for example. The fuel cells we are studying are run at high temperature, and the waste heat (heat we loose from the fuel cell) can be used to heat the house and produce hot water, while the electricity can be used in the home. In effect these units look like water heaters that produce electricity. The efficiency of these systems can be as high as 90%, if this waste heat is used. This means we are using the world’s resources up to three times more efficiently.
Until we can produce and store hydrogen in a better way than we do (obviously hydrogen is the cleanest fuel, as it only produces steam, but does not exist naturally in nature and has to be made), we must in the short term utilize our current resources more efficiently. The end goal is to use hydrogen, of course.
Some of our other research involves developing new materials to make more efficient batteries, such as the lithium battery we use in our lap tops. Here we are studying what is called a lithium-air battery which is more efficient, and has a greater range than the lithium ion battery we currently use. However, it has stability problems, and as such we are looking at methods of increasing its stability and allowing for a longer life system. Finally we are studying methods of using a fuel cell in reverse, which is called an ele- ctrochemical reactor, which elect- ochemically makes chemicals more easily, and potentially much more cheaply, than traditional chemical routes. In summary our group is very interested in the future of the energy and electricity generation. We focus on how to make our limited fuel reserves last much longer before we move away from a hydrocarbon economy completely, which may be some time off.
저작권자 © 포항공대신문 무단전재 및 재배포 금지
