Min Enze, an academician of China Academy of Engineering, revealed in a recent speech at Huazhong University of Science and Technology that some cities in China will sell "green oil" containing 5% microalgae biodiesel. However, due to the constraints of cost and production conditions, it will take time for this "green oil" to be vigorously promoted.
Academician Min Enze calculated an account: If clean fuel containing 5% biodiesel is promoted, the demand for biodiesel will be 6 million tons according to China's oil consumption. The economic and ecological benefits of this technology are very considerable. "Under the microscope, seaweed is like an oil gourd, 7-8 times higher than rape and peanuts, and 10 times higher than corn." Li Naisheng, dean of Shandong Institute of Ocean Engineering, said that using marine microalgae to produce biodiesel is a new direction in the international new energy field.
Experts pointed out that the area of saline-alkali land in China reached 65.438+0.5 billion mu. If microalgae are cultivated in 14% saline-alkali land, the amount of diesel oil produced can meet 50% of the national oil demand under the mature technology.
Pan Kehou, a professor at China Ocean University, said that microalgae are rich in resources, which will not destroy the ecosystem due to harvest, and can be cultivated in large quantities without occupying cultivated land. In addition, it has high photosynthetic efficiency and short growth cycle, and its annual output per unit area is dozens or even hundreds of times that of grain. Moreover, the lipid content of microalgae is 20% to 70%, which is far beyond the scope of land plants. It can not only produce biodiesel or ethanol, but also become a new raw material for hydrogen production.
Academician Min Enze said that after using straw to produce ethanol gasoline, using microalgae to produce biodiesel is the latest "green" fuel technology, but although the technology is mature, it will take time for microalgae fuel production system to be put into production. He believes that if ordinary vehicles want to "drink" microalgae biodiesel, they must also cross three thresholds: First, the cost. The industrial chain of microalgae fuel oil project is very long, the cultivation cost of algae is very high, and the price of finished products is many times that of petroleum; Secondly, the microalgae biodiesel project needs to be put into production on a large scale, and the production scale of each research institution is very small; Third, it is difficult to find a suitable production site. In algae culture, the density of algae can only reach 1%~2%. If the density is too high, algae can't absorb sunlight. The growth of microalgae needs high sunlight and moisture, which determines the need for large-scale venues.
Microalgae is a kind of bioenergy with great potential, but its scale and cost are two bottlenecks in its development. Therefore, it is necessary to take microalgae biodiesel technology as a long-term undertaking, and pay attention to the selection of schemes and routes. The microalgae oil production project initiated by Shanghai Science and Technology Commission has achieved initial results. Researchers are stepping up research and development of a new microalgae oil-making technology that can not only produce diesel oil but also reduce carbon dioxide emissions, and are ready to take the lead in applying this achievement to the treatment of waste gas from coal-fired power plants.
Miao Xiaoling, an associate professor in charge of algae oil production research, said that the research team is solving the problem of variety selection. There are nearly 30,000 known species of algae in the world, among which those with high oil content may not grow fast or adapt to the environment with high carbon dioxide concentration. Researchers hope to find the most suitable species, so that microalgae can absorb a lot of carbon dioxide, and make nutrients needed for growth through chlorophyll photosynthesis, extract oil from it, and then prepare biodiesel. This biodiesel is similar to the traditional petrochemical diesel in nature and composition, and some indexes, such as the low-temperature starting performance of the engine, are even better.
In order to realize the industrialization of microalgae diesel oil, the research group plans to develop continuous harvesting, dehydration and drying and microalgae oil production technologies suitable for industrial production, establish a large microalgae oil production plant, and cultivate microalgae in large containers. According to the assumption, daytime sunlight and industrial carbon dioxide waste gas will create suitable growth conditions for microalgae; At night, photosynthesis stops, but microalgae can still be "fed" with industrial wastewater, so that they can use the sugar in wastewater to make nutrients; The microalgae residue after "oil pressing" can be used as fuel for new biomass energy boilers. After this round of green cycle, microalgae diesel can reduce the carbon emissions of automobiles to zero.
Professor Luo Yonghao, director of the Biomass Energy Research Center of Shanghai Jiaotong University, believes that there are many large coal-fired power plants in Shanghai, and 99% of the gas they emit is carbon dioxide. Using this technology, microalgae oil can be recovered locally.
It is understood that algae contain a large amount of bio-oil, and some varieties have an oil content as high as 70%. They have high photosynthetic efficiency and rapid growth, and can complete a growth cycle in two weeks at most. The research shows that the annual oil output per hectare is only 0/.20 liters of corn/kloc-0, 440 liters of soybean and 0/.5000 to 80000 liters of algae/kloc-0. Algae will be a very potential source of biodiesel. Shell, Chevron and other oil giants, as well as Bill Gates, chairman of Microsoft, who is committed to the development of new energy, have invested heavily in the research and development of microalgae oil in the past two years. The production of microalgae oil needs the support of national projects.
In view of the important energy value of microalgae and the deepening of international research on energy microalgae, some experts suggest that China should immediately start the research on microalgae ethanol and oil production technology, pay attention to the dynamic tracking of microalgae hydrogen production, and make long-term planning.
China has a strong R&D force in the basic research of energy microalgae. Many universities and research institutes have undertaken a number of national and provincial studies on microalgae classification, breeding and preservation technology, and have a large number of freshwater and seawater microalgae germplasm resources. At present, China has been at the forefront of the world in the large-scale culture of microalgae.
Experts suggest that the production of biodiesel from microalgae is of great political, economic and scientific significance, and the state should increase scientific and technological support to make it a national project. The production of microalgae oil needs the support of national projects. Ministries and commissions such as the Ministry of Science and Technology, the National Development and Reform Commission, the Ministry of Finance, and the Energy Bureau should be inclined to microalgae oil production in scientific and technological projects, encourage relevant enterprises to develop automation equipment for microalgae oil production, and vigorously promote the industrialization of microalgae oil production. From 1976, the United States began to study microalgae energy, which solved the problem of producing high-fat microalgae from the waste gas produced by fossil fuels. Although this plan was terminated due to the simplification of funds and the high cost of algae oil production, American scientists have cultivated an engineering cyclops rich in oil. Under laboratory conditions, the oil content of the algae can reach more than 60% (3 ~ 12 times higher than that of microalgae in natural state), and the outdoor yield can also be increased to more than 40%, which provides a solid foundation for later research.
In 2006, two companies in the United States established a commercial system that can be connected with the flue gas of 1040 MW power plant, and successfully used carbon dioxide in flue gas for large-scale photosynthetic culture of microalgae, transforming microalgae into biological "crude oil". In 2007, the United States announced the Micro Manhattan Project supported by the National Energy Administration. It is planned to realize the industrialization of biodiesel production by microalgae in 20 10, and the research and development of various technologies will be accelerated in an all-round way.
In 2007, an Israeli company demonstrated the technology of using algae to absorb carbon dioxide and convert solar energy into biomass energy. Every 5 kg of algae can produce 1 liter of fuel.
In addition, in the production of ethanol by microalgae, the United States has developed a patent to produce ethanol by microalgae instead of sugar fermentation; Two Japanese companies have jointly developed a new technology to convert carbon dioxide into fuel ethanol by microalgae, and it is planned to develop related equipment and put it into industrial production in 20 10.