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Discussion and conclusion
¨ Limited co-operation from externally involved companies. Very few data are obtained from companies, which could have several reasons, e.g. the data asked for were not available, the confidential nature of some data (for example, data disclosing sensitive processes information or data concerning yield), the company feeling uncomfortable with the potential use of data. And last but not least: 100% data are not available from the companies if they have not performed LCA on the product. ¨ Limited co-operation from the purchasing department on raw material data collection, which is the main reason for not getting a good response from the externally involved companies. ¨ Limited co-operation from the manufacturing departments in Sauer-Danfoss. Data collection was performed on each department, which were involved in the manufacturing of the hydraulic motor. The production department’s co-operation was much better than the engineering (designer), purchasing and exporting department’s co-operation. ¨ Limited co-operation on manufacturing processes data. 75% response was obtained in the data collection based on questionnaires given to the manufacturers. The main reason was that the manufactures were busy and felt that it was a waste of time, and they were also hesitant to answer the questions. For example, the workers were not interested to disclose information about manufacturing pieces per day or per hour by machine. By pressing them to provide us information, some times the estimation was too high in reality, which then created major uncertainties in data collection. ¨ Very limited co-operation from the human resource department. Very limited information on ancillary substances ((Oils) used to manufacture different parts) was obtained under confidential conditions. 50% of the obtained data was usable. The main reasons behind not obtaining correct data is that Sauer-Danfoss depends on Danfoss company employees, because in July 2000 one part of Danfoss was emerged into another company “Sauer”, which is now working independently. Still Danfoss employees control some parts and materials. It was up to Danfoss to give information on ancillary substances or not. ¨ Lack of information on different oils and non-obtainable literature on oil products. ¨ No co-operation from the exporting department: Information on the use stage is not gathered because of a lack of corporation from the exporting department. Letters are prepared to the end user, but I was not allowed to ask questions to the end user without the exporting department’s permission, therefore the letters were submitted to the exporting department for further action. No response was obtained in the study period. Data on use stage were estimated with the help of Tom Tychsen (company supervisor), literature data and personal experience. Data collection availability as mentioned above is a significant problem in performing the LCA on the hydraulic product. Therefore, some suggestions have been made in the recommendation section for further studies. Detailed discussion on productThe main purpose of this LCA was to evaluate potentials impacts, including environmental impact potentials and resource consumptions from cradle to grave of the hydraulic motor. The LCA is performed stage-wise and finally on the full product system in order to achieve the precise evaluation of the hydraulic product system. This LCA is to a high degree influenced by a number of limitations and uncertainties concerning the scenarios evaluated in the LCA. Hence uncertainties due to the data used and the significance of the most important parameters are also evaluated. The are still some important unanswered questions in the different stages of the hydraulic product system, which are discussed below: Raw
material+ Semi product stage: The raw material production contributes to most of the categories significantly in the hydraulic product system. As shown in the profiles, the raw materials productions are directly related with the impact potentials obtained to the different waste categories. It should be noted that the ladle furnace process slag although with a zero allocation factor, is considered within the hazardous waste category. What if the category for the slag would be slag and for ashes the ash one? The slag and ashes category has got a higher normalization factor than the hazardous waste, which means that the normalization result would be less important and the impact potential scenario on the waste categories would change again. It should be noted that the slag is not considered hazardous waste by the authorities. On the other hand, it does not contain toxic substances. Furthermore the impact potentials on the environment (such as e.g. pollution of groundwater, pollution of drinking water or consumption of land) from waste are not converted, because it has as yet not been possible to include the dumping of waste in landfills as a process and to predict the relationship between quantity of waste and environmental impacts, this part of the LCA is still immature and a concept under development, which may have big contribution in the hydraulic product system, because of @ 40% of the material is deposited into the landfill from the various routes of the product system. The high amount of impact potentials for persistent toxicity and eco-toxicity are due to the cast iron and steel manufacturing processes. Large amounts of heavy metals and gases including zinc, lead, iron oxide, mercury carbon monoxide (CO) and CO2 are emitted into the different compartments (air, water and soil) in the cast iron and steel productions processes. As discussed in detail in the previous section (3.1), the most important source in the raw materials stage to toxicity impacts of heavy metals emission is during melting processes in the cast iron and steel production materials. By going deep into different studies, many methods are adopted in order to prevent the pollution from the raw materials production such as improved dust filters, re-circulation of cooling water, scrap improvement etc, but no single method can prevent the emission 100%. There is no single concrete solution that seems to be valid, the problem could be reduced dramatically if manufactures of cast iron and steel can avoid the use of heavy metals in their product and if the process is completely covered, and no air and water is exchanged from the processed room without being cleaned first. Alternatively the designer can design and build in such a way that the disassembly and sorting of different materials is easier. Manufacturing
Stage: The environmental characteristics in the manufacturing stage, the ancillary substances and electricity consumption are significant parameters. Many of these ancillary substances have not been investigated thoroughly, and it may in any case be difficult to obtain information on them from the suppliers and company employees, therefore the eco-toxicity is included and the human toxicity is neglected because of the information gap and time limitations. The assessment of eco-toxicity potentials is thus based on a rather fragile database and assumptions. The further investigation on ancillary substances may reflect results (human toxicity and eco- toxicity) significantly. The heavy metals during manufacturing processes washed with processed water and flow into the wastewater after use are not included in the LCA. The heavy metals emissions to wastewater may contribute to potential impact results also. The wastewater from Sauer-Danfoss is disposed into a municipal wastewater treatment plant, which is not acceptable because industrial wastewater contains many wasted heavy metals during manufacturing processes and oils and chemicals, which cannot be treated in the municipal wastewater treatment plant properly. In order to prevent pollution, the wastewater supply must be connected with industrial wastewater treatment plant. In this study, the standard wastewater treatment plant data is used to calculate emissions to water, soil and air from the ancillary substances in the manufacturing stage, which may not disclose the real effects. The electricity consumption in the manufacturing stage contributes to impact potentials significantly as mentioned above in the previous chapter and therefore need to be improved. By improving 10% of the electricity consumption, one piece of OMV/W-800 will save 7.188 kWh electricity consumption, which is presently costing up to 4.456 Kr/piece. The hydraulic motor efficiency is most significant in the product, which is a major factor in reduction of impact potentials in the product system. As in the detailed discussed in the previous chapter, the efficiency can be improved by: ¨ Reducing roughness in the hydraulic motors parts holes. ¨ Improving tightness between hydraulic flow parts. ¨ By using higher concentration oils. ¨ By improving distributor functionality. ¨ By redesigning and replacing materials. ¨ Replacing mechanical technology into electrical on most significant parts. Use
stage: The use stage is the most significant stage in the hydraulic product system, which contributes to environmental impact potentials on a large scale. The two main parameters mainly creating large amount of potentials are hydraulic oil consumption in the drain system, which is further contributing to potentials in the disposal stage through incineration and the oil combustion in the diesel engine. Answering the question, can the impact from the hydraulic oil be reduced by replacing hydraulic oils with other less concentrated oils and with water: the impact from the hydraulic oil can be reduced, but at the same time it creates so many other problems, which may increase the impact potentials. For example, the function of the hydraulic oil is to rotate the hydraulic motor’s internal system with hydraulic pressure. The concentrated hydraulic oil increases the working efficiency in the system and reduces the possibility of explosions. The diluted oil loses the hydraulic pressure and efficiency in the system. Therefore concentrated hydraulic oil is recommended to use in the use stage. The other function of the hydraulic oil is to make lubrication in the system and prevent the corrosion in the system. The hydraulic oil can replace with other oils, which are used with water in concentration 2% to 10%. It will solve problems related to impact potentials from the hydraulic oil in the product, but the motor will decrease the system output and efficiency, because of diluted oil will loss more mechanical efficiency and will increase the output, which is already unacceptable parameter in the product. On the other hand, it will loss volumetric pressure, but volumetric pressure problem also can be solved by increasing the quantity of oil (diluted oil) and increase the volume of the system e.g. big loop and increase volume of the pipes and increase the motor size, but same time it will increase others problems such as increase in quantity of oil and weight of the all related products (because big volume need more material) and transport from cradle to grave, materials and efficiency of the full hydraulic system. It is important to answer another question, the hydraulic fluid system can convert into water fluid system, but it will increase resource consumptions in the product, materials for all products, loss higher efficiency similar as mentioned in the previous lines, because system needs special material, which prevents corrosion in the hydraulic product system, big loop, big volume. The hydraulic oil contributes 0.188 PE to the global warming, 0.07PE to the acidification and 14 mPR for the resource consumption for the crude oil. The parameter ‘gasoline energy consumption’ is found to be one of the main parameters in detailed investigation by comparing with others. Please remember that the 1% of efficiency in the product system lost 13533MJ (318 liters gasoline oil) energy, which contribute to 0.163PE (16%) to the global warming and 9.5% in average to the others significant impact categories. The 1% of efficiency loss contributes 1.2% (12.8mPR) of crude oil in the product system, which is quite a lot. Totally 97% significant potentials for global warming, acidification, nutrient enrichment, photochemical ozone formation, human toxicity, crude oil and natural gas derive from the gasoline oil combustion in the hydraulic product system. Disposal
stage: The scenarios on disposal material seem to be reasonable in the European countries, but these scenarios may not be acceptable for the Asian countries. For example; ¨ The cast iron and steel scrap recovery factor may decrease or increase. ¨ Most of the disposal materials from the melting industries are used for linking roads equipments. ¨ The steel and cast iron recycling methodologies are different country to country. ¨ The packaging materials corrugated cardboard and plastic bags are not incinerated. Almost 75% (personal comments) cardboard and plastic materials are recycled. ¨ Oil is not incinerated after use, which is mostly used in the other applications and machineries for lubrication. The steel/cast iron recycling data are the company specific data on recycling materials and rest data are assumed, which do not found to be important in the product system. Weight
of the hydraulic motor: It is very important to discuss the weight of the hydraulic motor, which seems to be large with respect to product function. By using the “MECEEO model” it can be seen that the material effects raw material extraction and manufacturing significantly. In the Sauer-Danfoss working period, it is found that the designer is not aware of what types of problems s/he can prevent by choosing the right material and designing environmental friendly products instead of decorated designs of the product. Here it important to give one example, the TMT type motor and OMV type motors are used for the same function in the application and have the same output. But in weight, 7 kg less material is used in the product. By reducing 7kg of material in OMV/W-800 product, significant changes can be seen in the results profile of the hydraulic product system. For example, by reducing 7 kg of material 48ML energy consumption can be saved (calculated with MECEEO model), which directly and positively affects Sauer-Danfoss’ economy. On the other hand, by reducing material significant changes can be seen in the impact potentials profile. Life time: It does not mean that all motors work a full lifetime. The actual life span of a hydraulic motor depends on application (machine) lifetime in which it is installed. It will dispose with the application, when the application will not usable anymore, which will affect the actual results significantly. Sauer-Danfoss has adjusted the life span of the hydraulic motor to 10-20 years, which seems to be an over estimation. If the estimation is correct then the results will double in significance the results profile, which will heighten values for the product. EDIP
PC-tool: Most
of the data are used from the EDIP-database system. The data in the EDIP
database are relatively old, hereby it can be argued that newer data may change
the results, thus more recent data are inserted by making a comparison with the
EDIP database and different literature databases whenever possible. Since the
main goal of this LCA is to primarily identify the most significant impact
potentials on the environment, it is estimated that the lack of data does not
have any affect on the conclusions. |
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