Recovery and characterisation of carbon fibres from waste CFRP using supercritical n-butanol

ABSTRACT

The high-performance carbon fibres can be recycled from waste carbon fibre/epoxy resin composites by supercritical n-butanol. Recycling experiment designed by response surface method was used to investigate quantitative relation between degradation rate of epoxy resin and process parameters. Thus, the optimum process parameters could be obtained, and effects of process parameters and layers on degradation rate and mechanical performance of the recycled carbon fibres were analysed. The tensile strength of the recycled carbon fibre under the optimum process parameters was 94.53% of that of the original carbon fibre, tensile modulus was 93.57% of that of the original carbon fibre and interfacial shear strength was 90% of that of the original carbon fibre.     

Has EU ETS caused carbon leakage in the EU carbon-intensive industries?A study from the perspective of bilateral trade

Reducing carbon leakage is one of the important reasons that was put forward by the EU for their border adjustment tax proposal.However,there are not many empirical evidences supporting significant carbon leakage in the EU carbonintensive industries.This paper applied the structural breakpoint test for the time series of import and export of cement,aluminum,and steel between EU and China.No significant structural changes were detected in the import and export of cement and aluminum.However,there proved to be two breakpoints,i.e.,2003 and 2008,in the import and export of steel,in which at the second point the overall level of steel import increased.Furthermore,Granger causality test was applied to the carbon price from European Climate Exchange and the import and export of steel.It was found that the carbon price was the Granger cause for the changes of steel import,but not the Granger cause for the export.The results of the study showed that the impacts of EU ETS on the EU carbon-intensive industries were limited.Among the three industries,partial evidence of carbon leakage was only found in the steel industry.Therefore,reducing carbon leakage could not serve as a convincing justification for border adjustment tax.     

基于最优拍卖数量和资金再分配模型的碳市场有偿分配机制研究

拍卖作为一种有偿分配机制已经确立为我国碳市场配额分配的基本方式之一,而拍卖机制的灵活运用以及与市场运行之间的关系也成为实践中亟待解决的难题。传统的排放权拍卖理论以政府收入最大化作为目标函数,并没有将企业预算和交易策略纳入到分析框架中,同时对于拍卖收入资金的再分配方法缺乏可行的指导。本文将企业的成本约束(或预算)作为一个因素引入,提出了最优拍卖数量模型以及基于双重红利思想的资金再分配模型。分析表明最优拍卖数量由企业的边际减排成本和二级市场弹性系数决定,二级市场弹性系数则取决于排放的不确定性水平;边际减排成本越高的企业,其承受的拍卖成本随着拍卖价格增长越快,这可能导致减排空间小的企业承担的拍卖成本增长过高,从而产生不公平问题,因此本文提出了一种基于多轮竞价的资金分配策略,根据企业参加拍卖的投标情况间接评估企业的边际减排成本水平,并制定相应的补贴标准。最后以广东碳市场为例,从市场结构、履约成本、市场价格三个方面深入讨论了拍卖对碳市场的影响以及最优参数的选择策略。广东的经验为拍卖机制的引入提供了良好的建议:在二级市场流动性不足,价格发现能力较弱的情况下,引入拍卖机制可以快速建立一级市场的价格发现机制;由于历史法的不可靠,拍卖会将履约成本分配不合理的问题进一步放大,加剧市场的不公平问题,甚至出现劣币驱逐良币的现象,但拍卖收入资金的循环利用可以在一定程度上纠正这一问题;短期内拍卖底价是政府建立市场预期的辅助工具,是在二级市场供求关系尚未建立时的一种过渡手段,但从长期来看随着二级市场的成熟,底价政策应该逐渐放松或退出,建立起一级市场价格与二级市场价格联动的定价机制。     

欧盟碳价影响因素研究及其对中国的启示

作为一项市场创新和政策创新,即将启动的中国全国性碳市场备受国内外关注。为保证其成功建立与平稳发展,相关经验借鉴已刻不容缓,但作为投石问路的7大试点碳市场发展层次不齐,可供参考的模式有限,因此研究全球第一大碳市场——欧盟碳排放交易体系(EU ETS)及其对中国的可参照性尤为迫切;而作为市场是否成熟的风向标,碳价规律性特征的挖掘尤为重要。前期国内外学者分别发现CER价格、原油价格、煤炭价格、天然气价格、欧洲工业指数、联合国气候变化大会、政府政策、极寒天气、暖冬天气、自然灾害、重大事件等多种因素都有可能引起EUA期货价格波动。本研究通过引入MIV-BP神经网络模型,对EU ETS二期和三期的EUA期货价格进行训练和测试,模拟了上述11个因素对EUA价格的影响,弥补了传统计量模型难以同时处理较多变量及不能整合定性与定量变量等缺点。通过对EU ETS二期1 149组和三期775组数据的挖掘,得出了各变量对EUA期货价格的影响程度。其中,二期运行阶段各变量影响程度从大到小排序为:自然灾害COPCER极寒天气Coal重大事件Brent政府政策Stock600Gas暖冬天气;三期运行阶段各变量影响程度从大到小排序为:COPStock600Coal自然灾害极寒天气重大事件政府政策BrentGasCER暖冬天气。最后,本研究对二、三期各变量对碳价影响程度的变化进行了解释,并对中国未来建立全国性碳市场提出了以下四点建议:(1)稳定碳市场参与主体预期;(2)完善核证减排抵消机制,保持政策稳定;(3)配额分配考虑区域差异;(4)建立配额应急机制。     

欧盟“碳边境调节机制”要点、影响及应对

2019年《欧洲绿色新政》重提“碳边境调节机制”即碳关税引起各方关注,随后欧盟开展了一系列活动,推进碳关税制定和立法进程。2021年3月10日欧洲议会表决通过《建立符合世贸组织要求的欧盟碳边境调节机制（CBAM）》的决议,同年7月14日欧盟委员会公布提交欧洲议会和欧盟理事会审议的《建立碳边境调节机制》的提案,开启了碳关税正式立法进程。综合两版案文来看,CBAM在执行方式上将与欧盟排放贸易体系（EU ETS）关联,碳价格执行EU ETS当期价格;覆盖领域上,第一个执行期主要覆盖水泥、电力、肥料、钢铁、铝等五个行业;执行范围是除了欧盟国家或已实现与EU ETS连接的国家包括冰岛、列支敦士登、挪威、瑞士等,其余国家均属于执行对象;核算方式上,如果申报人不能提供直接排放的实测数据,则采用出口国相关领域产品的平均排放强度或者欧盟该类产品性能最差的10%设施的平均排放强度。此外,CBAM机制还包含了“避免双重征碳税” “防止规避征税”等内容。作者测算了2021年3月和7月两个方案对中国的经济影响,分别为：第一,欧洲议会3月CBAM决议经济影响,基于欧盟排放贸易体系（EU ETS）第四阶段“碳泄漏”清单涉及相关行业测算,如果清单中所有对欧出口商品都被征税,征税总额为32.90亿美元（碳配额价格按70欧元/t,即80美元/t计价）。第二,欧盟委员会7月CBAM提案经济影响,课题组对5个将要实施行业进行测算,中国需支付8.34亿美元碳关税,其中钢铁6.19亿美元,铝2.08亿美元,水泥和肥料被征税0.01亿美元和0.06亿美元。采用全球可计算一般均衡模型测算,中国GDP损失为1.86亿美元。目前来看,欧盟CBAM无论是政治上还是技术上都还面临诸多挑战,但可以预见作为单边措施欧盟依然会积极推进CBAM立法进程,并抛出一份其他国家难以接受的实施方案作为平衡其所谓竞争力损失并向其他国家施压提升全球减排努力的谈判筹码。反对单边碳关税措施是中国一贯立场,面对欧盟新一轮碳关税进程,中国可继续坚持气候公约“共同但有区别的责任”原则予以明确反对,并从政治、法律、经济、技术等层面整体布局,反对CBAM实施。     

Sustainable monitoring of concrete structures: strength and durability performance of polymer-modified self-sensing concrete

Concrete structures all over the world are reaching the end of their service life sooner than expected. This is due to the fact that ordinary Portland cement-based concrete deteriorates under environmental actions and also that structural inspections and conservation actions are expensive. Besides, as they consume energy and non-renewable resources, they have negative environmental impacts. Self-sensing concrete provides an alternative way of monitoring concrete-reinforced structures at a much lesser cost and with lesser environmental impact. Although the short-term mechanical properties of these materials are usually well documented, the long-term durability issues about carbon fibre concrete still deserve further investigations. This paper reports some investigation of the strength and durability characteristics of several concrete mixtures modified with different percentages of polymer and carbon fibre addition. The results show that the addition of carbon fibre decreases the strength and increases water penetration under pressure and also increases chloride diffusion, whereas polymer addition is responsible for a denser microstructure and higher concrete durability.     

WASTE MANAGEMENT AND SUSTAINABLE DEVELOPMENT IN SOUTH AFRICA

Waste management is emerging as a key sector for sustainable development in South Africa with opportunities for enhancing investments in carbon credits that target reduction of methane from landfills and moveable assets in relation to environmentally sound equipment required for effective waste management. In the past, the waste management sector was dominated by private sector with selective operations in what makes business sense through recycling of saleable products. Materials mostly recycled included paper and hard board, plastics, glass, tinplate and aluminum. The rest of the waste materials estimated at 10.2 million tons of both general and hazardous end up in landfills. This trend is now getting reversed as development agencies such as Deutsche Gesellschaft für Technische Zusammenarbeit Gmbh (GTZ), Danish International Development Agency (DANIDA), Danish Co-operation for Environment and Development (DANCED) and Development Bank of Southern Africa (DBSA) are identifying opportunities in the sector for sustainable development purposes. Two key areas for investments include capturing methane emissions from landfills for trading in carbon markets and financing both physical and moveable assets to enhance sustainable development. However, the challenges for cost-effectiveness, efficiency and sustainability in the sector prevail in relation to lack of sound knowledge to design and implement integrated programmes that incorporate environment, development and sustainability. Also, inadequate capacity at municipal levels to administer waste management programmes and inability to collect rates and taxes for effective management of landfills constraint effectiveness and efficiency of the sector. Overall, financial resources are imperative to waste management and sustainable development as the sector requires capital investments for necessary infrastructure.