Characterization Of Tailpipe Emissions And Cost-Benefit Analysis Of Emission Control Measures For Agricultural And Industrial Equipment In China

The population of non-road agricultural and industrial equipment in China has been increasing in recent years and had exceeded 170 million in 2017.Mainly dieselfueled,these equipment are key sources of nitrogen oxides and particulate matter emissions,which have a serious impact on the urban air quality and public health.Since emission control in China for non-road equipment is still at its early stage,there exists a large data gap on emissions and activities of agricultural and industrial equipment under real-world conditions,leading to a huge uncertainty in existing emission inventory for non-road mobile sources.Therefore,characterization of in-use activities and its associated emissions for non-road equipment,prediction of its future trend,and evaluation of multiple emission control measures are of great significance to reduce emissions from non-road equipment and help improve the air quality.These are also the objectives of this study.This study used field survey to acquire activity data of non-road agricultural and industrial equipment.The survey methods mainly include in-person visits,onsite/phone interview and literature review.The main collecting information includes:equipment type,model,manufacturer,engine displacement,rated power,production and delivery date,exhaust emissions after-treatment facilities,average annual use time,the emission standards implemented,and the annual average fuel consumption.The information investigated by this study were used to analyze the influence of equipment type,equipment age,rated power and region on the activity.Furthermore,a portable emission measurement system（PEMS）was developed to measure the in-use emissions of typical non-road agricultural and industrial equipment.The measured pollutants include: CO,HC,NO and PM_2.5.Engine operation parameters were also measured,including engine revolutions per minute,manifold absolute pressure,intake air temperature,and exhaust temperature.Three duty modes,i.e.,idling,moving and working were defined to represent the duty cycles of agricultural and industrial equipment.The collected data of emissions and engine operation parameters were post-processed and used for further analysis.Historical population data of non-road agricultural and industrial equipment of China was then used to predict the growth trend of agricultural and industrial equipment population in 2018-2025 via a BP neural network method.Combined with the investigated activities and the measured emission factors,the emissions in 2015-2025 from agricultural and industrial equipment of China were estimated.In addition,cost-benefit analysis was used by this study to evaluate three different emission control measures,including turn-over,engine replacement and engine retrofit with an economical and feasible measure also being explored.The key findings of this study are shown as follows:（1）Current status of non-road agriculture and industrial equipment in ChinaApproximately 1200 agricultural and industrial equipment in China were surveyed for activity in this study.The results show that,the activity of non-road equipment is affected by various factors such as equipment type,working conditions,power,equipment age,region,etc.The annual usage time of agricultural equipment can vary between 217-1721 hr·yr^-1,with annual fuel consumption varying 0.2-10.5 t·yr^-1.The annual usage time of industrial equipment varies between 1439-4332 hr·yr^-1,with annual fuel consumption varying 4.9-54.9 t·yr^-1 depending on the equipment type.Furthermore,the annual usage time generally decreases with the increase of equipment age,with hourly fuel consumption increasing with the increase of equipment age.It is estimated that the annual usage time of agricultural equipment decreased as it ages with a rate of approximately 41 hours per year,while the fuel consumption increased as it aged with a rate of 0.43 kg per hour.The annual usage time of industrial equipment decreased as it ages with a rate of approximately 145 hours per year,while the fuel consumption increased as it aged with a rate of 0.94 kg per hour.There exist as large as three times differences in annual usage time due to geographical area differences for the same equipment type.The current Guideline for Emission Inventory Development for Non-Road Equipment of China give the recommended value of 150-500 hr·yr^-1 for the annual usage time of agricultural equipment,and the recommended value of 770 hr·yr^-1 for the annual usage time of industrial equipment regardless of the equipment type.The fuel consumption data is not involved.Thus,the data of annual usage time and fuel consumption investigated in this study will help to supplement the activity database and improve the accuracy of the emission inventory of non-road equipment in China.（2）Characterization of emissions from non-road agricultural and industrial equipment in ChinaIn this study,a portable emission measurement system（PEMS）was developed and used for in-use emission measurement s of 53 non-road agricultural and industrial equipment.The measurement results show that,depending on the equipment type,operating conditions and the pollutant types,the emissions for agricultural equipment can be up to 12 times different.Emissions from industrial equipment can differ up to 14 times.The emissions of agricultural and industrial equipment in moving and working modes are usually higher than that in idling.For example,the average mass rates of CO,HC,NO and PM_2.5 in moving mode of agricultural equipment is 1.7,1.8,3.9 and 4.8 times of that in idling mode respectively,while those in working mode are 6.1,1.7,4.9 and 11.8 times of that in idling mode,respectively.For industrial equipment,the average mass emission rates of CO,HC,NO and PM_2.5 in moving mode are 1.8,2.4,2.6 and 3.9 times that of idling mode,respectively,while those in working modes are 2.0,2.1,2.9 and 5.6 times that of idling modes,respectively.Furthermore,the emissions of agricultural and industrial equipment are significantly affected by factors such as power and emission standards compliance.For example,the emissions increase with the increase of engine power,and decrease with the continuous tightening emission standards,which is consistent with previous studies.The emission factors measured in this study are different from those recommended in the Guideline for Emission Inventory Development for Non-Road Equipment of China.For agricultural equipment,the fuel-based NO composite emission factor measured by this study is 0.2 to 1.9 times of recommended emission factor in the Guideline,with fuelbased PM_2.5 composite emission factor being 1.7-15.1 times,respectively.For industrial equipment,65% of NO emission factors measured by this study are lower than the recommended values in the Guideline,while 80% of PM_2.5 emission factors measured by this study are higher than the recommended values in the Guideline.This indicates that,the measured emission factors of agricultural and industrial equipment in this study will help to supplement and improve the existing Guideline.Furthermore,the measurement of non-road equipment emissions under real-world conditions plays an important role in improving the accuracy of the emission inventory.（3）Growth of population and its associated emission inventory of non-road agricultural and industrial equipment in ChinaThis study used a BP network method to predict population growth of non-road agricultural and industrial equipment and its associated emission inventory in China.From 2015 to 2025,for population growth,the population of agricultural equipment will increase linearly,while that of industrial equipment will be relatively flat;for emission inventory,emissions of CO,HC,NO_x and PM_2.5 from agricultural equipment in 2015 range from 1.0-12.4 million tons,and the emissions of CO,HC,NO_x and PM_2.5 from industrial equipment range from 0.3-3.2 million tons,with NO_x emissions being the largest and PM_2.5 emissions being the lowest.The primary processing equipment for agricultural products and tractors are the largest contribution of pollutants of among all types of agricultural equipment,and that of excavators and loaders are the largest among all types of industrial equipment.In general,as emission standards for nonroad equipment become more and more stringently from 2015 to 2025,emissions from agriculture and industrial equipment appear to become smaller.By 2020,CO,HC,PM_2.5 emissions from agricultural equipment will be 1.9-8.7% higher than 2015,respectively,with NO_x emissions being 16.0% lower than 2015.By 2025,those from agricultural equipment will be 0.1-26.2% lower than 2020,respectively.For industrial equipment,the emissions showed a downward trend.By 2020,emissions of CO,HC,NO_x and PM_2.5 will be 0.6-31.8% lower than those in 2015,with NO_x being the biggest drop.By 2025,emissions will also be further reduced by 4.7-23.6% compared with 2020.Due to the increasingly strict emission control of road mobile sources,their contribution to mobile sources will decrease year by year,while in contrast,the contribution of emissions from non-road equipment will become increasingly prominent in future years.（4）Evaluation of emission control measures for non-road agricultural and industrial equipmentCost-benefit analysis results of three different non-road equipment emission control measures,i.e.,equipment turn-over,engine replacement and engine retrofit,show that: The investment in emission control measures of agricultural equipment is significantly higher than that of industrial equipment to achieve the same reduction of emissions.Among the three emission control measures,the cost of equipment turnover is significantly higher than that of engine replacement and engine retrofit.For all types of agricultural equipment,engine retrofit cost is higher than the cost of engine replacement.For industrial equipment,the cost of replacement of most types is higher than the cost of engine retrofit,except forklifts and pavers.Therefore,when making the overall decisions,it is better to adopt engine replacement to reduce emissions for agricultural equipment.For industrial equipment,adopting engine retrofit is more economical and effective.From the perspective of benefits,due to the huge population of agricultural equipment in China and the large number of old equipment,after adopting emission reduction measures to make all the equipment meet the National Emission Standard IV,agricultural equipment can achieve better emission reduction effect than industrial equipment.Agricultural equipment can reduce NO_x 1.8-5.0×10⁶ tons per year,and PM_2.5 can reduce 5.0-6.6×10⁵ tons per year.Industrial equipment can reduce NO_x about 0.7-5.1×10⁵ tons per year,and PM_2.5 can reduce about 0.6-1.2×10⁵ tons per year.Assuming that 106.7 billion RMB will be invested in the prevention and control of emissions from agricultural and industrial equipment in 2020,maximum reduction benefits can be achieved by taking the following measures: by replacing 12 to 33% of the old engines of agricultural equipment with new ones,NO_x emissions will be reduced by 8.3×10⁵ tons,and PM_2.5 emissions will be reduced by 9.0×10⁴ tons.If 32% of excavators,loaders,cranes,road rollers and bulldozers are equipped with after-treatment devices,NO_x emissions will be reduced by 1.3×10⁵ tons,and PM_2.5 emissions will be reduced by 2.0×10⁴ tons.For forklifts,pavers and graders,79%,93% and 34% of old mechanical engines were replaced with new engines,respectively,NO_x emissions could be reduced by 6.0×10⁴ tons and PM_2.5 by 2.0×10³ tons.In general,emissions from agricultural and industrial equipment are impacted by a variety of factors including population,activity,emission factors and many others.Thus,in order to improve the accuracy of emission inventory for non-road agricultural and industrial equipment,a detailed database of activity and emission factor,extensive and localized in-use emissions measurements are needed.Furthermore,as a more and more stringent emission standards are enforced on on-road vehicles,emissions from non-road equipment will be likely to contribute more emissions than those from onroad equipment.Therefore,more attentions should be paid to the non-road equipment.A cost-effective emission control measure will be imperative for emission reduction from non-road equipment.