trends and future of sustainable development - TransEco

2008). In this situation, potential oil and gas refining will increase fossil fuel reserves, thus causing therisks of the exponential rise of greenhouse effect, which can result in all kinds of catastrophes to ourplanet Earth and its inhabitants. One of the evidently exiting problems is that the high number of onroaddiesel vehicles implies that emissions from the engines contribute significantly to the atmosphericlevels of the most important greenhouse gas, CO 2 and other urban pollutants such as CO, NO x , unburnedhydrocarbons, particulate matters and aromatics (Kalam et al., 2003). To confront the global climatechanges, biofuels (biodiesel, bioethanol, biogas, etc.), as a renewable and alternative energy, aredeveloped and being put into practice.Under the above background, microalgae have overwhelmingly received a lot of attention as a newbiomass source for the production of biofuel. Several strengths account for the reasons why microalgaecan be utilized as one of the most promising biofuel feedstock. First, microalgae have highphotosynthesis efficiency and can grow very fast. Chisti (2008) illustrates that microalgae can producemany times as much oil as the other materials (e.g. soybean, corn, rapeseed, palm, sunflower) per unit ofgrowing area every year. Second, microalgae can be cultivated without occupying farmlands (Aikins etal., 2009), and thus can reduce the possible damage to the agricultural ecosystem and the traditionalfood webs. Third, fresh water is not essential and nutrients can be supplied by wastewater (Mulbry et al.,2009; Wang et al., 2009) and CO 2 by combustion gas (Wang et al., 2008) during cultivation. Fourth,they can be collected very quickly, obviously accelerating the biodiesel production process (Avagyan,2008). Fifth, the property of their uniform cell structure with no bark, stems, branches or leaves makethe commercial production attractive (Avagyan, 2008), thus making the operation and control ofreproduction conditions much more practical. Finally, the physical and fuel properties of biodiesel frommicroalgal oil in general (e.g. density, viscosity, acid value, heating value, etc.) are comparable to thoseof fuel diesel (Miao & Wu, 2006).Recently, microalgae-based biofuel (MBB) has been enjoying a surge in popularity since it hasbecome one of researchers’ keenest interest in energy field and most of their studies have been focusedon the following aspects: 1) microalgae culture system, including raceway, photobioreactor (PBR) andfermenter, 2) collection, screening and classification of microalgae, 3) biochemical and physiologicalstudies on lipid material production, 4) molecular biology and genetic engineering, and 5) systemanalysis and resource assessment. Plenty of relative findings and technological breakthroughs have beenobtained until now, theoretically and/or empirically. And most of them have been emphasized on thepositive strengths of implementation of microalgae as a biofuel feedstock, such as available biomass,high oil content, carbon neutral, etc. However, there is limited detailed published information availableon the sustainability concerns or risks related with MBB production.2. Purpose and perspectiveThis is an exploratory study and the purpose of this research is to map out the environmental, economic,social and cultural risks of MBB production from sustainability perspective. Identifying the coreenvironmental, economic, social and cultural impacts associated with microalgae biofuel production isthe first step in supporting the development of a sustainable biofuel industry. This is especiallyimportant for the following two reasons: for one thing, today more than ever before, unpredictableenvironmental issues strongly bound with the economic, social and cultural impacts of the energy sector489