우리나라 시설 재배면적은 2015년 기준 52,526ha이고 이 중 난방면적은 15,878ha이다. 이중 석유를 이용하여 난방하는 온실 면적은 13,314ha로서 전체 난방면적의 84%를 차지하고 있다. 고가의 시설비가 투자된 자동화 온실에서 겨울철에 난방기를 사용하여 채소 및 화훼류를 재배할 경우 생산비 중에 난방 비가 차지하는 비중이 40%를 웃돌고 있다. 우리나라의 폐윤활유 발생량은 2015년에는 249,965kL이고 이중 회수량은 197,469kL로서 발생량의 79% 수준이다. 또한 회수한 폐윤활유의 재활용량은 2015년 기 준 195,691kL로서 재활용율이 99%에 달한다. 그러므로 저가의 대체연료 사용에 따른 농가 소득 증대의 관점에서 볼 때 시설난방에 폐윤활유를 사용하는 것은 매우 중요하다고 할 수 있다. 따라서 본 연구는 폐윤활유를 농용 난방기의 연료로서의 사용 가능성을 분석하고자 하였다. 연구결과 농용 난방기의 연소 가스온도는 폐윤활유를 연료로서 사용하였을 때가 중유를 연료로서 사용했을 때에 비해 평균 6.1%, 경 유를 연료로 사용하였을 때보다 평균 3.1% 높게 나타났다.

This paper presents the estimation of actual recyclable amounts and the evaluation of waste oil recycling processes atrecycling facilities using material flow analysis (MFA). The estimation of actual recycling rates through the processes ofwaste lubricating oils is a very important subject not only in the point of view oil recycling efficiency by energy conversionprocesses but also in the perspective of the recycling technology level. In this study, the recycling processes and recyclingrates of waste lubricating oil recycling facilities were evaluated by using a MFA approach, a total of 10 site visits anda total of 30 site questionnaires in Korea. The MFA methodology based on mass balance approach applied to identifythe inputs and outputs of waste oils during the recycling processes at waste oil recycling facilities. It is necessary todetermine the composition and flows of the input materials to be recycled and foreign substances in a waste recyclingfacility. A complete understanding of the waste flows in the processes along with the site visit and data surveys for therecycling facilities was required to develop a material flow for the processes and determine the process yield by differenttreatment methods (chemical distillation, vacuum distillation and high temperature pyrolysis). The results show that onaverage the process yields for chemical distillation, vacuum distillation, and high temperature pyrolysis were 89.9±7.7%,77.9±16.1%, and 57.9±9.3%, respectively. During the chemical distillation method, water in waste oils was a majorfraction (>50%), while the vacuum distillation method resulted oil large amounts of oil sludge produced during therecycling process. The process yields for different treatment methods depended upon several factors including the qualityof incoming waste oils, the type and operating conditions of recycling processes that are applied to. Based on the materialflow analysis in this study, the actual recycled amount of waste oil was estimated to be approximately 260,809 ton in 2011.