The carbon footprint and non-renewable energy demand of algae-derived biodiesel
The carbon footprint and non-renewable energy demand of algae-derived biodiesel
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DOI：
10.1016/j.apenergy.2013.09.027
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发表时间：
2014-01-01
期刊：
影响因子：
11.2
通讯作者：
Kraft, Markus
中科院分区：
文献类型：
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作者：
Azadi, Pooya;Brownbridge, George;Kraft, Markus
我们从温室气体(GHG)排放和不可再生能源消耗方面确定了以藻类为原料生产生物柴油的不同策略对环境的影响，然后将结果与从化石资源获得的常规和合成柴油的结果进行了比较。在所有考虑的方案中，开放池塘水道中的藻类养殖和将藻油转化为生物柴油的酯交换过程是共同要素。湿法采油残渣的转化可考虑厌氧消化和水热气化，干法采油残渣的转化可考虑气化-热电联产和气化-费托工艺。生物柴油单位能量温室气体排放量分别为：水热气化41g e-CO2/mJ(B)，厌氧消化86g e-CO2/mJ(B)，气化发电109g e-CO2/mJ(B)，气化-费托气化124g e-CO2/mJ(B)。正如预期的那样，不可再生能源消耗与温室气体数值密切相关。此外，使用高维模型表示(HDMR)方法，对整个输入参数空间进行全局灵敏度分析，以根据它们对关键可持续性指标的影响对它们进行排名。考虑到各参数变化的合理范围，对湿法萃取路线影响最大的输入参数包括萃取器的能量需求和提取的海藻厌氧消化或水热气化产生的甲烷产率。干法提取路线的主要工艺输入参数包括藻类含油量、干燥机能源需求和藻类年生产率。这些结果表明，只有在实施低碳解决方案(如太阳能干燥)以帮助降低原料的水分含量的情况下，才能证明从干燥的原料中生产藻类生物柴油是可持续的。(C)2013爱思唯尔有限公司。保留所有权利。
We determine the environmental impact of different biodiesel production strategies from algae feedstock in terms of greenhouse gas (GHG) emissions and non-renewable energy consumption, we then benchmark the results against those of conventional and synthetic diesel obtained from fossil resources. The algae cultivation in open pond raceways and the transesterification process for the conversion of algae oil into biodiesel constitute the common elements among all considered scenarios. Anaerobic digestion and hydrothermal gasification are considered for the conversion of the residues from the wet oil extraction route; while integrated gasification-heat and power generation and gasification-Fischer-Tropsch processes are considered for the conversion of the residues from the dry oil extraction route. The GHG emissions per unit energy of the biodiesel are calculated as follows: 41 g e-CO2/MJ(b) for hydrothermal gasification, 86 g e-CO2/MJ(b) for anaerobic digestion, 109 g e-CO2/MJ(b) for gasification-power generation, and 124 g e-CO2/MJ(b) for gasification-Fischer-Tropsch. As expected, non-renewable energy consumptions are closely correlated to the GHG values. Also, using the High Dimensional Model Representation (HDMR) method, a global sensitivity analysis over the entire space of input parameters is performed to rank them with respect to their influence on key sustainability metrics. Considering reasonable ranges over which each parameter can vary, the most influential input parameters for the wet extraction route include extractor energy demand and methane yield generated from anaerobic digestion or hydrothermal gasification of the oil extracted-algae. The dominant process input parameters for the dry extraction route include algae oil content, dryer energy demand, and algae annual productivity. The results imply that algal biodiesel production from a dried feedstock may only prove sustainable if a low carbon solution such as solar drying is implemented to help reducing the water content of the feedstock. (C) 2013 Elsevier Ltd. All rights reserved.