Thread Content
http://news.cbbf.cn/bencandy.php?id=912&fid=3 Regarding the raw materials for biomass energy, attention has long been focused on traditional aged grains, lignin, animal fats, etc., while algae, which are aquatic plants and also hold great potential for development, have not received enough recognition. In fact, as an important renewable resource, algae possess outstanding characteristics such as wide distribution, large biomass, high photosynthetic efficiency, strong environmental adaptability, short growth cycles, and high yields. Further development and utilization of algae, especially microalgae, will provide new sources of resources. Global Energy Network believes that microalgae hold great potential as a source of energy; their cells contain unique primary or secondary metabolites with complex chemical compositions, and their solar energy conversion efficiency can reach 3.5%. They represent a potential resource for the production of pharmaceuticals, fine chemicals, and new types of fuels. Fatty acids obtained from microalgae can be converted into fatty acid methyl esters, namely biodiesel ； Under the action of zeolite catalysts, microalgae can be converted thermochemically to produce gasoline-type fuels ； Green algae that grow in seawater are able to accumulate large amounts of free glycerol to balance the salt concentration in their environment, with the glycerol content accounting for up to 85% of their dry weight. Currently, researchers are gradually realizing that microalgae, as a source of bioenergy, hold significant potential for development in various aspects: they reproduce rapidly and require few nutrients, mainly sunlight, water, and CO2, without competing with agriculture and livestock farming for land ； Compared to other plants, algae contain higher levels of lipids and soluble polysaccharides, which can be used to produce biodiesel or ethanol; they also hold promise as a new source for hydrogen production ； Compared to lignocellulosic materials, algae have a higher photosynthetic efficiency than trees ； Easy to crush and dry, with low preprocessing costs ； The biomass fuel obtained through pyrolysis has a high calorific value, averaging up to 33 MJ/kg, which is 1.6 times that of wood or crop straws ； By using photosynthesis for growth and reproduction to capture CO2 from exhaust gases, it can help protect the environment. Due to its unique advantages, microalgae can be used to remove CO2 from flue gas, although there are no reports of industrial applications at present. Research in this field focuses on three main aspects: first, the screening and cultivation of algae species capable of efficiently fixing CO2. Currently, suitable algae species include cyanobacteria and green algae, with Chlorella being particularly notable among the green algae ； The second is the exploration of the mechanisms by which microalgae fix CO2; the focus of research is to understand the forms in which inorganic carbon is utilized, the mechanisms of CO2 concentration, and the impact of high concentrations of CO2 on microalgal growth ； Third is the research on microalgae cultivation conditions, which involves exploring the optimization of factors such as nutrients, light, temperature, pH value, and aeration to meet the growth needs of microalgae; this is an effective way to reduce the production costs of microalgae. Developing microalgae as energy resource crops is mainly aimed at producing ethanol, biodiesel, fuel oil, or hydrogen. Experts from the Fushun Petrochemical Research Institute believe that there are many ways to convert biomass into bioenergy, and each method has its own advantages and disadvantages. The appropriate conversion method is chosen based on factors such as the source and characteristics of the biomass, the desired form of conversion, environmental protection requirements, and economic benefits. In this field, the United States has developed patents for using freely floating single-celled microalgae as a substitute for sugar in the fermentation process to produce ethanol; however, there is no industrial application yet ； Two Japanese companies have jointly developed a new technology for converting CO2 into fuel ethanol using microalgae, with plans to develop the relevant equipment by 2010 ； Through catalytic pyrolysis technology, microalgae can be converted into fuel oils with high aromatic content and high octane rating, and the emerging liquefaction-based pyrolysis technique further reduces the costs of this process. Furthermore, the commercialization of microalgae cultivation for hydrogen production holds promise, but it is only economical when the efficiency of converting sunlight into hydrogen reaches 10%; currently, this efficiency is only 0.1%, and there are still a number of technical issues that need to be resolved. Algae have many uses; in our country, they are primarily used as health foods and medicines. In fact, research on using algae to produce fuel is of great significance from both environmental and energy perspectives. The large-scale outbreak of blue-green algae in Lake Taihu in 2007 prompted people to consider ways to manage and utilize these algae. Converting algae into fuel oil might be a solution to turning the problems caused by blue-green algae in Lake Taihu into opportunities, but there are still many issues that need to be resolved before this can become an economically viable method of energy production. For example, the harvesting of algal cells, the removal of water from them, the reduction of ash content, and the separation of the target product. Global Energy Network believes that in research on the development and utilization of microalgae, attention should be focused on parameters such as the water content inside and outside the cells, the levels of lipids and proteins, and the ratio of cellulose to lignin, in order to determine the target products for further research. It is understood that the Fushun Petrochemical Research Institute has carried out research on the utilization of microalgae, screening and culturing algae capable of utilizing CO2 and accumulating oils, and has determined the cultivation conditions and growth characteristics of typical algae species such as Chlorella vulgaris, Chlorella pyrenoidosa, and Cyclotella. In the future, further research will be conducted on algae strain improvement, photoreactors, as well as the separation of target products such as oils, sugars, and cellulose.