Pyrolysis Characteristics Research And Life Cycle Assessment On Utilization Of Microalgae Resources

Biomass resources include wood and wood wastes, energy crops, aquatic plants, agricultural crops and their waste by-products, municipal wastes and animal wastes. Among these, microalgae have been suggested as very good candidates for fuel production because of their advantages of higher photosynthetic efficiency, higher biomass production and faster growth compared to those lignocellulosic materials. Though the microalgae biomass can be used as a solid fuel because of its high heating value, we direct our attention to the conversion of it into other products since they are more friendly to the environment.Through the industry analysis and elementary analysis experiments of the microalgae, we can get the basic nature of microalgae burning: a higher proportion of carbon content, the equivalent heat value to coal, a much higher proportion of volatile and easy to ignition, more oxygen content, making the air feeding much less when it burning. The TG and DTG curves of microalgae pyrolysis under different heating rate were performed by thermal gravimetric analysis. That ignition temperature, combustion kinetic parameters were affected by the heating rate at different extents. As the increasing of heating rate, the temperatures correspond to ignition, maximum weight loss rate and maximum weight loss rate increased. The maximum weight loss rate increased the most of all the combustion kinetic parameters.The whole life of methanol fuel, produced by microalgae biomass which is a kind of renewable energy, is evaluated by using a method of life cycle assessment (LCA). LCA has been used to identify and quantify the environment emissions and energy efficiency of the system throughout the whole life cycle, including microalgae cultivation, methanol conversion, transport, and end-use. From sensitivity analysis on life cycle inventory, we can see that CO2 emission decreased while the microalgae yield increased, that's mainly because CO2 is the main raw material for photosynthesis in the growth of microalgae. The energy conversion efficiency of Fuel methanol is 1.24. In this study, microalgae cultivation was a major contributor, which led us to an idea that the energy balance would be improved by using microalgae which was produced in natural environment without an artificial cultivation. The environmental impact loading of microalgae-based fuel methanol is 73.281PET2000. The effect of photochemical ozone formation is the highest of all the calculated categorization impacts.The electric power production from microalgae by gasification is analyzed by a Life Cycle Assessment approach which is applied to calculate the values of the environmental impact load and the depletion of natural resources coefficient. Coal consumption was the main proportion of the resource depletion, accounted for 98.7%, much more than the oil consumption, which was resulted by the energy structure in China. Soot and ash takes up the biggest proportion of environmental impact loading. The proportions of environmental impact loading occupied by other environmental impact including global warming, acidification, and nutrient enrichment are small.