A Study On The Sustainability Of China's Steel Industry During 2005–2015 Based On Emergy

In recent years,with the acceleration of urbanization and industrialization,the demand for steel products is increasing.China has been the largest steel producer around the world since 1996.Due to the characteristics of the China's iron and steel sector?CISS?,its main production process includes sintering,coking,iron-making,steel making and steel-rolling.These processes often consume large amounts of mineral resources and fossil energy.As a result,the steel sector has accelerated the exploitation and consumption of corresponding mineral resources and pollution emissions,and then challenged the resources capacity and the environmental capacity.The steel sector should take much responsibility for social economic sustainable development due to its high energy consumption and high environmental emissions.However,China's industrialization and urbanization are still at the middle stage,and they still need the support of CISS.In the foreseeable future,the steel industry will be still the basic industry of China.Therefore,in the context of the fast economic growth and the ecological civilization building,energy conservation and emission reduction is still one of the main tasks for Chinese government during and after the“13th”five-year plan period to achieve win-win results for economic development and environmental improvement.Therefore,the development of the steel sector requires an effective evaluation method to explore its comprehensive performance,so as to provide decision-makers with some effective improvement measures.This study adopted emergy analysis to evaluate the environmental sustainability of CISS.The classic emergy indicators are improved through integrating eco-indicator 99,dilution method,disability adjusted life years and land occupation into classic emergy analysis.Besides,emissions'impacts are quantified and then divided into ecological service and emergy loss,and next they are further integrated into environmental loading ratio and emergy yield ratio,respectively.Finally,emergy sustainable index is improved according to the improved environmental loading ratio and improved emergy yield ratio.The environmental sustainability of CISS in 2005 to 2015 was studied using the proposed methods and improved indicators.Meanwhile,some classic emergy-based indicators of the CISS were compared with the relevant indicator values of the Chinese economy.The results show that:?1?During the 2005-2015 periods,the annual mean percent for local renewable emergy,local nonrenewable emergy,renewable purchased emergy and nonrenewable purchased emergy is 1.13%,68.24%,1.01%and 29.63%respectively.Nonrenewable inputs?N+NP?share the absolute proportion of total input,and iron ore and coal are major contributors.?2?The unit emergy value of China's steel during the 2005-2015 period ranges between 4.76E+21⁵.56E+21 sej/Mt?based on the emergy baseline 12.00E+24 sej/yr?.During this period,the unit emergy value of steel products increased along a fluctuation path,which indicates the decreasing trends of production efficiency of the sector in2005-2015.?3?As the only alternative to iron ore,steel scrap recycling is backward.The ratio of steel scrap recycling?RSSR?ranges between 10.15¹9.68%during the study period.?4?The value of ecological services ranges between 2.84E+23¹.64E+24 sej,and gradually declined from 2005 to 2015,especially,it declined significantly during the2005-2008 period.Ecological services are mainly used to dilute volatile phenol and NH₄⁺-N in wastewater.The emergy loss?ranging between 2.57E+22¹.04E+23 sej?increases along a slight fluctuation path during the 2005-2014 period,which is mainly derived from dust and carbon dioxide in air pollutants.Furthermore,it is found that emergy loss percent declines during the 2005-2009 periods,increases in 2009-2011,declines from2011 to 2013,increases during the 2013-2014 period,and finally it decreases from 2014 to2015.?5?Improved emergy yield ratio?IEYR?changes obviously in fluctuation before 2011,and it then keeps stable after 2011.This indicator is influenced by the purchased inputs,and this indicator reaches the lowest value in 2009 due to consumption of massive purchased iron ore.The value of improved emergy yield ratio ranges between 2.85³.53during the study period.When emissions'impacts are ignored,this indicator slightly increases,ranges between 2.89³.58.?6?Improved environmental loading ratio?IELR?changes between 35.05⁷1.81 from2005 to 2015,it waves obviously before 2010,and then increases after 2010.The indicator is mainly affected by the ratio of nonrenewable inputs to renewable inputs.Combined with the indicator R%?1.63³.85?,it is found that the increase of this indicator is mainly caused by the changes of the renewable input,and it arrives at the smallest value in 2009 mainly due to increasing share of steel scrap in the purchased resources.When emissions'impacts are ignored,this indicator?ELR ranging between 24.99⁶0.25?decreases,especially before 2008.?7?The value of improved emergy sustainable index?IESI?ranges between0.047⁰.081,and it keeps stable during the 2005-2015 period except 2009.This indicator has the biggest value in 2009 due to the increasing share of imported steel scrap.However,the improved emergy sustainable index is small during the total study period,which is mainly caused by abundant nonrenewable inputs.When emissions'impacts are ignored,this indicator?ESI?changes between 0.052⁰.132,and it increases obviously before 2008but keeps stable after 2008 compared with IESI.Based on the study results,the corresponding suggestions are put forward,including improving resource efficiency,emphasizing iron ore management,optimizing energy structure,strengthening steel scrap recycling and reuse,emphasizing pollution control strategies,and innovating the management of the CISS.