Comprehensive Efficiency Evaluation Of Fermentative Biohydrogen Production Technology Based On Emergy Theory

According to the comprehensive efficiency evaluation for biohydrogen production technology, this paper constructed environment-resource-technology comprehensive efficiency model on the basis of biohydrogen production technology, with the combination of ternary diagram and emergy analysis method. On the basis of these results, emergy system index of demonstration project of biohydrogen production was calculated on the industrial level, the comparation of biohydrogen and other renewable energy production technology was analysized at the same time.In environment-resource-technology comprehensive efficiency model, the technology flow was divided into three part: sludge culture, reactor and substrate by analyzing biohydrogen production theory. The introduction of emergy theory converted various ecological flows to the emergy flow and constructed environment-resource-technology comprehensive efficiency model. The model has two parts: emergy comprehensive efficiency index calculation model and ternary diagram of structure coefficient for emergy input, each part of the model was explained. The application scheme was designed, which includes emergy analysis step, emergy system diagram and emergy analysis table.The comprehensive efficiency evaluation on experimental process level for biohydrogen production technology was from the three part of sludge culture, reactor and substrate. Sludge culture includes mixed and pure culture. First, experiment data of four pretreatment methods was collected, those experiments used the same CSTR reactor and glucose as substrate. Structure coefficient for emergy input was fitted by ternary diagram of, combined with the relation curve between emergy input and hydrogen output. Comprehensive efficiency index were calculated and evaluated. Pure culture technology was evaluated with the same way. In analysis result, EIR of heat pretreatment method was lowest, that was 0.24; ESI was on middle level for four methods, and alkali pretreatment was 4.28, which was highest, HYE of heat pretreatment method is higher than other methods. So, heat method is suitable for sludge culture. ESI of pure culture was lower than 1 when take glucose as substrate, this kind of culture method was unsustainable development.In reactor part, data from experiments of four kinds of normal reactors, CSTR, UASB, EGSB and AFB, was summarized and calculated. Structure coefficient for emergy input was fitted by ternary diagram, combined with the relation curve between emergy input and hydrogen output, and comprehensive efficiency index were calculated and evaluated. In analysis result, we can find out that when cultured by aeration oxidation and wastewater, EIR of EGSB was 0.37, which was lowest. Both ESI were higher than 1 when took CSTR and EGSB as reactor, those technology were middle level sustainable, but ESI of CSTR was lower than EGSB. The highest HYE of EGSB was 0.33, which was also the highest of four kinds, and numerical intervals of EGSB and CSTR was higher than other kinds. It was clear from the results of relation curve between emergy input and hydrogen output that, with the increase of emergy consumption, increased value of hydrogen production was higher than other kinds. So, comprehensive efficiency index of EGSB was highest. In addition, the effect of operation condition of reator to emergy consumption for hydrogen production was discussed. The result showed, for CSTR reactor, higher emergy output can be got by low increase of emergy consumption through reasonable reactor regulation.In substrate part, comprehensive efficiency index of molasses wastewater, straw and MSW were evaluated. On the basis of emergy consumption calculation, structure coefficient for emergy input was fitted by ternary diagram. The result was: EYR of molasses wastewater was highest, which was 5.26. ELR of all substrates was low, those had small effect to environment. ESR of molasses wastewater was 0.78, which was highest. ESI of all substrates was higher than 1, those technology had sustainable development potential and molasses wastewater was best. In conclusion, comprehensive efficiency index of molasses wastewater was best, this substrate was most suitable for biohydrogen production.Emergy input and output of demonstration project of biohydrogen production are calculated on industrial level and emergy output of intelligence accounts for 3.3% and 3.7% of total output. It indicates that emergy output of intelligence has key effect in initial stage of industrialization for biohydrogen production technology. EYR of demonstration project is next to nuclear power and biodiesel, it indicates that the production efficiency of demonstration project is high; EIR is lower than global average emergy input ratio; ELR is lower than agriculture system, and much lower than bio-ethanol; the low ESR shows that demonstration project need to be reduced nonrenewable subsidiary energy; EAR is lower than biodiesel, the government efforts to foster the project need to be strengthen. RER is very high, it shows a high renewable capacity of the project, the substrate of wastewater is a kind of resource will not be depleted; ESI = 2.31, it indicates that the project has activity and development potential, can be developed in a long term.