基于层次分析法和模糊综合评价的沼气工程技术筛选

不同沼气工程技术对地域自然条件、环境制约条件、原料种类等因素的适应性有较大差异,科学客观的沼气工程技术筛选方法,是保证沼气工程长期稳定发挥其最大能效的重要基础。该文提出了基于层次分析法(analytic hierarchy process,AHP)和模糊综合评价的沼气工程技术筛选方法和决策流程,构建了沼气工程技术筛选的指标体系;以领域专家实地调查结果为基础,通过AHP法获得沼气工程技术筛选不同指标的权重,然后采用模糊综合评价方法对沼气工程技术进行排序。利用该方法筛选的结果与武汉地区的实际运行效果一致。采用AHP和模糊综合评价方法相结合解决复杂的多因素决策问题,既能克服AHP指标不易量化的主观性,又能避免模糊综合评价方法对指标权重的忽视,可为沼气工程技术筛选提供科学方法。

Biogas engineering technology screening based on analytic hierarchy process and fuzzy comprehensive evaluation

Abstract: Biogas typically refers to a gas produced by the breakdown of organic matter in the absence of oxygen. Biogas, like solar and wind energy, is a renewable energy source. Biogas is produced by anaerobic digestion with anaerobic bacteria or fermentation of biodegradable materials, usually from regionally available raw materials such as manure, sewage, municipal waste, green waste, plant material, and crops. Biogas comprises primarily of methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes. This energy release allows biogas to be used as a fuel. Biogas can be used as a fuel in any country for any heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat. In China, during last year this biogas technology has met high growth rates, and it has become the main way to use waste of livestock manure. Currently, a huge variety of biogas technologies or techniques are available at home and abroad. The effects of biogas technologies differs in different regions. Using scientific methods to screen out the right biogas technology, which is applicable, economically viable and environmentally friendly, for certain area has great significance.Comprehensive evaluation on one certain technology in a specific area is the key issue to select and integrate the modern technology. In order to construct the comprehensive evaluation index system and method for one certain technology in China, construction on comprehensive evaluation index system and method are usually put forward and comprehensive evaluation index system are normally established with research method of literature analysis based on social economic-natural compound ecosystem. In this study, based on analysis of currently available approaches to screening the technologies for biogas and methods to solve the multi-parameter problem in decision making, an AHP and fuzzy comprehensive evaluation based decision making process was applied to establish index system for biogas technologies screening. Weights of the indices for the screening were worked out through investigation by experts in this field using AHP, and then the biogas technologies were collated with fuzzy comprehensive evaluation method. This decision making process was verified with the actual screening for a case of biogas technologies application site in China. AHP and fuzzy comprehensive evaluation method combined could be used to solve the complicated multi-factor problem in decision making, thus not only overcome the issue of subjectiveness of AHP in handling hard-to-quantify indices, but also avoid the shortcoming of neglecting index weights with fuzzy comprehensive evaluation method. It is, therefore, a good tool to screen biogas techniques for recycling of agriculture waste.Comparison of operating effects between two biogas technologies was carried out, and the results from calculations based on AHP and fuzzy comprehensive evaluation method were consist with the facts of the real application at two sites adopted with two biogas technologies. Compared with completely mixed anaerobic technologies, red-sludge plastic anaerobic technology had better effects in terms of consumption of waste. In addition, red-sludge plastic anaerobic technology generate more electricity to meet up to needs of local village in Hubei on electricity expenditure, and provide better solution on the non source pollution contaminating water and soil, and even potentially help reduce released two main gases, nitrogen dioxide and methane, that cause global climate change. In all, the methods in this study will provide the methodology reference for assessing, selecting, integrating and promoting biogas technology in China.