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.