摘要
If substantial amounts of CO_(2),which according to actual scenarios may in the future be captured from industrial processes and power generation,shall be utilized effectively,scalable energy efficient technologies will be required.Thus,a survey was performed to assess a large variety of applications utilizing CO_(2) chemically(e.g.,production of synthesis-gas,methanol synthesis),biologically(e.g.,CO_(2) as fertilizer in green houses,production of algae),or physically(enhancement of fossil fuel recovery,use as refrigerant).For each of the processes,material and energy balances were set up.Starting with pure CO_(2) at standard conditions,expenditure for transport and further process specific treatment were included.Based on these calculations,the avoidance of greenhouse gas emissions by applying the discussed technologies was evaluated.Based on the currently available technologies,applications for enhanced fossil fuel recovery turn out to be most attractive regarding the potential of utilizing large quantities of CO_(2)(total capacity>1000 Gt CO_(2))and producing significant amounts of marketable products on one hand and having good energy and material balances on the other hand(t_(CO_(2)-emitted)/t_(CO_(2)-utilized)<0.2-0.4).Nevertheless,large scale chemical fixation of CO_(2)providing valuable products like fuels is worth considering,if carbon-free energy sources are used to provide the process energy and H2 being essential as a reactant in a lot of chemical processes(e.g.,production of DME:t_(CO_(2)-emitted)/t_(CO_(2)-utilized)>0.34).Biological processes such as CO_(2) fixation using microalgae look attractive as long as energy and CO_(2) balance are considered.However,the development of effective photobioreactors for growing algae with low requirements for footprint area is a challenge.
