ارزيابي زنجيره توليد تا فرآوري شير از لحاظ مصرف انرژي و اثرات زيست‌محيطي (مطالعه موردي: شهرستان كرمانشاه)

Evaluating the Energy Consumption and Environmental Impacts in Milk Production Chain (Case Study: Kermanshah City of Iran)

ارزیابی چرخه زندگی محصولات و فرآورده‌های غذایی راهكاری سازنده جهت درك میزان مصرف انرژی و تولید آلاینده‌های زیست‌محیطی می‌باشد. فرآیند تولید محصولات لبنی اثرات قابل ملاحظه‌ای بر روی تغییرات زیست‌محیطی دارد. فعالیت‌های انجام شده در فرآیند تولید محصولات لبنی شامل سه بخش اصلی كارخانه لبنیات، واحدهای دامپروری و مزارع كشت علوفه، بر میزان تغییرات زیست‌محیطی اثرگذار است. در این تحقیق چرخه تولید محصولات لبنی در شهر كرمانشاه مورد بررسی قرار گرفت. جهت انجام این كار، چرخه تولید به دو بخش شامل تولید شیر خام در دامداری‌ها و تولید فرآورده‌های لبنی در كارخانه لبنیات تقسیم‌بندی شد. در هر بخش الگوی مصرف انرژی و بارهای زیست‌محیطی بررسی شدند. نتایج نشان دادند كه در بخش دامپروری، MJ 6286/29 انرژی برای مقدار شیر تولید شده در ماه مصرف شده است. همچنین خوراك مصرفی دام 45/12% از كل انرژی مصرفی را شامل شد كه بیشترین مقدار این انرژی به كنسانتره اختصاص داشت. كم‌ترین انرژی مصرفی نیز مربوط به نهاده ماشین با مقدار GJ 0/92 در ماه بوده است. ارزیابی چرخه زندگی تولید محصولات لبنی نشان داد كه در كارخانه لبنیات نهاده شیر خام ایجادكننده بسیاری از گروه‌های تأثیرگذار زیست‌محیطی به‌خصوص گروه‌های تقلیل خاك، سرطان‌زایی و اسیدی شدن می‌باشد. در واحدهای دامداری نیز، كنسانتره بیش از 90% در گروه‌های تأثیرگذار تقلیل خاك و سرطان‌زایی اثرگذار بوده است. استفاده از بیوگاز تولیدی در دامداری‌ها و آبگرمكن خورشیدی راهكار مناسبی در جهت تأمین قسمتی از نیاز به انرژی می‌باشد.

Introduction Life cycle assessment of food products is an appropriate method to understand the energy consumption and production of environmental burdens. Dairy production process has considerable effect on climate change in various ways, and the scale of these effects depends on the practices of dairy industry, dairy farmers and feed growers. This study examined the life cycle of production of dairy products in Kermanshah city. For this purpose, the whole life was divided in two sections: production of raw milk in dairy farm and dairy products in dairy industry. In each section the energy consumption patterns and environmental burdens were evaluated. Based on the results, the consumed energy in dairy farm was 6286.29 MJ for amount of produced milk in month. Also animal feed was the greatest energy consumer with the value of 45.12% that the maximum amount of this value was for concentrate. The minimum consumption of energy was for the machinery with 0.92 MJ in a month. Results of life cycle assessment of dairy products showed that in dairy industry raw milk input causes most of impact categories especially land use, carcinogens and acidification. In dairy farms, concentrate was effective more than 90% in production of impact categories included: land use and carcinogens. Using digesters for production biogas and solar water heaters in dairy farm can decrease fossil recourses. Materials and Methods Based on ISO 14044, standards provide an overview of the steps of an LCA: (1) Goal and Scope Definition; (2) Life Cycle Inventory Analysis; (3) Life Cycle Impact Assessment; and (4) Interpretation (ISO, 2006). In this study there were two sub-systems in the production line: dairy farm sub-system (1) and dairy factory sub-system (2). In the sub-system related to the dairy farm, the main product was milk. Determination of inputs and outputs in each sub-system, energy consumption, transportation and emissions to air and water as well as waste treatment are the requirements of LCI. However each of them has several components. These components are different in both sub-systems. All the detailed data about energy equivalent in dairy farm is shown in Table 1. More detailed data about inventories description of two sub-systems are shown in Tables 3 and 4. The SimaPro 7.3.2 was used for analyzing the collected data for calculating environmental burdens (Pré Consultants, 2012). Results and Discussion Based on the developed models with SimaPro software for dairy products in the factory, various emissions were generated including emissions into the air, soil and water. The most prevalent emissions are summarized in Table 7. In warm season about half of the milk is processed into drinking yoghurt. Since water is one half of the component of this product so more amount of drinking yoghurt can be achieved with lower energy consumption (about 50%). Furthermore, these results indicated that the magnitude of fossil fuels was much greater than all others. It was followed by land use and respiratory inorganics. The most amount of the consumption of the fossil fuels was the production of energy requirements for heating systems at boilers and tractors in dairy factory and farm, respectively. Also the transportation of raw milk to the dairy industry was another source of the pollution. Also the energy consumption pattern in the dairy farm revealed that the concentrate have high contribution in energy consumption. Conclusions Results of the energy consumption pattern showed that the animal feed was the greatest energy consumer with value of 45.12% and followed by electricity (36%). Energy consumption index for the fossil fuel was calculated about 3.8 that is higher than the global index. Production of raw milk in dairy farm is responsible in the production of impact categories especially land use, carcinogenic and acidification with contribution of 97.6%, 78%, and 63%, respectively. Also the amount of CO2-eq was estimated 2.71 kg for the production of 1kg ECM in cold seasons.