Biodiesel Production From Lipids In Wet Microalgae By Microwave And Bio-oil Production From Algal Residue By Hydrothermanl Reaction

Growing shortage of fossil energy sources and serious environmental pollution in the world today are the two facing urgent problems. Vigorously developing renewable energy is an inevitable requirement of the world’s energy security and sustainable development. It is frontier research hotspots and high-tech focus of competition that taking advantage of the large-scale farming of marine resources microalgae to absorb CO2and harvest high-grade liquid and gaseous fuels from biomass. Development of marine economy in the world has an important significance on a low carbon and circular economy. Microalgae as a representative of the third generation of energy have its unique advantages such as its high oil content, good oil quality, fast growing rate, not the occupation of cultivated land, reducing emissions of carbon dioxide and purifying environment. Therefore, it is received more and more attention.In order to solve the large energy consumption of dewatering microalgae and simplify the conventional two-step method (extract lipids from cells and transesterify lipids into biodiesel) to produce biodiesel, a novel process was proposed that wet microalgae biomass was directly converted into biodiesel by microwave irradiation. The influences of conventional thermal heating and microwave irradiation on biodiesel production from wet microalgae biomass were investigated, as well as the influences of two-step and one-step methods (simultaneously extract and transesterify lipids). It was found that about77.5%of wet microalgae cell walls were disrupted under microwave irradiation. The mass transfer rate of lipids through broken cell walls was 152times higher than that through unbroken cell walls. The biodiesel production rate and yield from wet microalgae biomass through one-step process by microwave irradiation were6times and1.3times higher than those from wet microalgae through two-step process by conventional heating.The paper proposes the grading use of microalgae resources, which is low energy consumption and high oil production as hydrothermal reaction. Namely bio-oil is directly extracted by use of wet algae through microwave-assisted heating, which is following converted to high-grade bio-diesel or aviation kerosene, and the algae residue is converted to residual oil by hydrothermal reaction. It solves the complex ingredients of the bio-oil from the microalgae hydrothermal reaction and difficulties in deoxidation denitrification. The experimental results showed that the total oil yield of bio-oil production from classification use of oil process is almost the same as the single hydrothermal reaction step. Moreover bio-oil is divided into two different grades lipids. which can be more effective use of its follow-up.