| The exploitation and utilization of biomass energy is an effective stratagem for relieving the pressure from conventional energy shortage and environment and establishing the sustainable energy system. Among biomass, microalga is suggested as a very good candidate for biomass energy production because of the advantage of larger biomass, faster growth and higher content of lipid components etc. In this paper, Dunaliella, a group of halophilous algae, was used as a bioenergy producter. High lipid-content in the cells of Dunaliella was obtained after environment-stress inducement and/or UV mutation. Most of the organic materials in the cells can be easily converted into renewable bio-oil and gases after pyrolysis. All of the main results were showed as follows:1. Fifteen species/strains of Dunaliella were cultured under defined conditions and harvested during their equilibrium phase of the growth curves. Total lipid contents of the cells were determined by the Soxhlet procedure. The experiment results suggested that lipid contents of nine species/strains of Dunaliella were more than 10% of their dry weight (10.4～18.3%) with the exception of six species/strains were 6.7～9.0% respectively.2. To find out the best suitable conditions for cell division and lipid accumulation of Dunaliella, two strains, designated as NO. 10 and NO.15, were studied together using orthogonal test. As a result, we found that 5mmol/L of nitrogen, 28℃, 15 000 lx of light intensity and 1.5mol/L of salinity were the best conditions for their growth, while the cultured condition of 1mmol/L of nitrogen, 33℃, 25 000 lx of light intensity and 0.5mol/L of salinity would induced the highest lipid accumulation.3. Two mutant strains of Dunaliella bardawil. H-42 (numbered as. 10), with the character of high lipid-content, have been isolated and identified after ultraviolet radiation. They were denominated as D.bardawil H-42 var.HL-1 (simply as HL-1) and D.bardawil H-42 var.HL-2 (simply as HL-2) , respectively. Lipid contents were determined by the soxhlet procedure. The results showed that total lipid contents of HL-1 and HL-2 were 21.1% and 20.5% (dry weight), which were increased as high as 31.9% and 28.1%, respectively. The RAPD test revealed that the genetic similarity between NO.10 and its mutant strain HL-1 and HL-2 was 0.797 and 0.718, respectively.4. We tried to culture Dunaliella outdoor by using of concentrated seawater with additional inorganic nutrients around one year. The results indicated that Dunaliella could suffer from the annual variation of temperature, sunlight, salinity, pH and the amount of bacteria of the seawater media and had a good harvest of biomass and lipid. Outdoor seawater-cultivation can be regarded as a simple and economical model system for large-scale culture of Dunaliella.5. The pyrolysis experiments of the biomass of Dunaliella were conducted in a fluid bed reactor. The main parameters of reaction temperature, reaction period and the quantities of catalyzer have been known according to a series of orthogonal experiments. In the exposure period the materials of algae powder were converted into a variety of products including charcoal, bio-oil and gases. It could be proved that the yield of bio-oil converted from the high lipid-content Dunaliella strains (HL-1& HL-2) could reach as high as 51.3～52.4% (dry weight) .It is surprise that the bio-oil originated from Dunaliella displayed a higher caloric value (34MJ/kg～35MJ/kg), which was about 2 times of wood. The yield of pyrolysis gas could reach as high as 20.9～25.6% (dry weight) .The total yield of bio-energy could reach as high as 73.3～76.9% (dry weight).
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