Saved СО2 emissions by using renewable sources for hot water yield in Bulgarian dairy farms

R. Georgiev1*, R. Slavov2, K. Peychev1, D. Georgiev1, S. Apostolov3, J. Ellingsen4, J. Tønnesen4

1Department of Agricultural Engineering, Faculty of Agriculture,Trakia University, 6000 Stara Zagora, Bulgaria
2Department of Animal Science – Ruminant Animals and Dairy Science, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 3Bioselena Foundation for Organic Agriculture, Bulgaria
4Royal Norwegian Society for Development, Norges Vel, Norway

(Manuscript received 13 September 2017; accepted for publication 10 November 2017)

Abstract. In 2014 – 2015 installations for hot water yield from renewable energy sources were built and tested in three dairy farms in Bulgaria. These replace the traditionally used electricity on farms with the aim of decarbonising the energy production. The newly built installations contain three modules for heat yield – from recuperation of the heat from the milked milk, from the solar energy and from wood pellets. In the course of one year the energy obtained from the renewable sources has been measured and assessed. The present article assesses the ecological benefits of the separate renewable sources which are used to reduce СО2 emissions, the main greenhouse gas. For this purpose, the method of environmental life cycle analysis (LCA) and assessment of heat/hot water generating systems was used. Coefficients for calculating the primary energy of the saved or replaced energy, as well as their respective carbon ratios, specific for Bulgaria, were used. The results obtained are related to identifying the specific quantities of saved CO2 emissions from the renewable sources used on the experimental farms. It has been found that about 52-57% of CO2 savings are due to the pellets used, 34-42% to the solar heat collectors and about 9% to the recuperated heat from the produced milk.

Study on energy flows of renewable sources for producing hot water on dairy farms

R. Georgiev1, K. Peychev1, D. Georgiev1, R. Slavov2*, S. Apostolov3, J. Ellingsen4, J. Tønnesen4

1Depertment of Agricultural Engineering, Faculty of Agriculture,Trakia University, 6000 Stara Zagora, Bulgaria
2Department of Animal Science – Ruminants and Dairy Farming, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 3Bioselena Foundation for Organic Agriculture, Bulgaria
4Royal Norwegian Society for Development, Norges Vel, Norway

(Manuscript received 10 May 2016; accepted for publication 2 August 2016)

Abstract. A system for producing hot water in three dairy farms has been designed and built. It consists of three modules of renewable energy sources – solar thermal installation, heating boiler on wood pellets and recuperative unit for utilizing heat from the milked milk. For storage of the heated water two thermal batteries are used. One of the thermal batteries is a low temperature one (40°С) and is designed to utilize energy from milk, the other one is high-temperature (80°С) and is designed to accumulate solar energy and energy from the pellet boiler. The year-round operation of the system on three different farms has been examined. For every month results were obtained about the relative share of each of the renewable energies. Each system produces annually respectively 11273 kWh, 13668 kWh and 10244 kWh of energy to heat water. The share of solar energy is between 34.7 – 43.0% in annual terms, in summer it reaches 85- 95%. The share of energy from pellets per year is 52 – 57%, in winter it reaches 65 – 96%, while the share of utilized energy from milked milk averaged 9.5% annually.

odbutton6