자원환경지질, 제 51 권, 제 1 호, 67-76, 2018 Econ. Environ. Geol., 51(1), 67-76, 2018 http://dx.doi.org/10.9719/eeg.2018.51.1.67 pissn 1225-7281 eissn 2288-7962 친환경에너지타운에서보어홀지중열저장 (BTES) 활용융복합열에너지공급시스템사례연구 심병완 * 한국지질자원연구원, 지질환경연구본부 International Case Studies on the Eco-friendly Energy Towns with Hybrid Thermal Energy Supply System and Borehole Thermal Energy Storage (BTES) Byoung Ohan Shim* Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 34132, Korea (Received: 11 December 2017 / Revised: 26 February 2018 / Accepted: 28 February 2018) This study reviews three eco-friendly energy towns with hybrid thermal energy supply systems and borehole thermal energy storage (BTES) in Canada and Denmark. The district heating and cooling systems were designed by using multi-source energy for the higher efficiency and reliability as well as environment. ADEU (Alexandra District Energy Utility) located at the developing area in the city of Richmond, Canada was designed to supply district energy with the installation of 726 borehole heat exchangers (BHEs) and a backup boiler using natural gas. DLSC (Drake Landing Solar Community) located in the town of Okotoks, Canada is a district system to store solar thermal energy underground during the summer season by seasonal BTES with 144 BHEs. Brædstrup Solpark district heating system located in Denmark has been conducted energy supply from multiple energy sources of solar thermal, heat pump, boiler plants and seasonal BTES with 48 BHEs. These systems are designed based on social and economic benefits as well as nature-friendly living space according to the city based energy perspective. Each system has the energy center which distribute the stored thermal energy to each house for heating during the winter season. The BHE depth and ground thermal storage volume are designed by the heating and cooling load as well as the condition of ground water flow and thermophysical properties of the ground. These systems have been proved the reliance and economic benefits by providing consistent energy supply with competitive energy price for several years. In addition, the several expansions of the service area in ADEU and Brædstrup Solpark have been processed based on energy supply master plan. In order to implement this kind of project in our country, the regulation and policy support of government or related federal organization are required. As well as the government have to make a energy management agency associated with long-term supply energy plan. Key words : eco-friendly energy town, hybrid thermal energy supply, borehole thermal energy storage (BTES), solar thermal, seasonal thermal energy storage 본연구는해외친환경에너지타운에서보어홀지중열저장 (BTES) 기술을활용한융복합열에너지공급시스템의 3 가지사례로서캐나다의 ADEU(Alexandra District Energy Utility) 및 DLSC(Drake Landing Solar Community) 와덴마크의 Brædstrup Solpark 를조사하였다. 이들지역냉난방시스템들은효율과지속가능성을높이기위하여다중에너지원을활용하고있다. ADEU 는리치몬드시에서 726 개의지중열교환기로이루어진지열필드및천연가스 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited. *Corresponding author: boshim@kigam.re.kr 67
68 심병완 백업보일러를이용한대규모지역에너지공급을위해개발되었다. 그리고캘거리시인근 Okotoks 에위치한 DLSC 는여름철에풍부한태양열에너지를 144 개의지중열교환기를통하여지중에저장하고겨울철난방을위해각주택에열에너지를분배하는계간축열방식의지역난방시스템이다. Brædstrup Solpark 지역난방시스템은태양열, 히트펌프, 보일러플랜트및계간축열을위한 48 개의지중열교환기로구성되며다중에너지원을이용하여열을저장한다. BTES 시추공의심도와축열량은지하수유동과지반의열물성에따라영향을많이받는다. 이러한시스템들은경쟁력있는에너지가격으로장기적인에너지를공급함으로서신뢰성과경제성을평가받았다. 그리고 ADEU 와 Brædstrup Solpark 는서비스영역확장을위한장기에너지공급계획을기반으로확장이진행중이다. 본조사를통하여이러한시스템들은사회 경제적인이익뿐만아니라환경적인관점이설계에반영되어있는것을알수있었다. 국내에서도이러한프로젝트를실시하기위해서는지방정부또는관련기관의에너지정책지원뿐만아니라, 관리기관설치를통한장기적인협력이필요하다. 주요어 : 친환경에너지타운, 융복합열공급, 보어홀지중열저장 (BTES), 태양열, 계간축열 1. 서론 최근우리나라는기후변화협약실천과온실가스배출감소와관련하여재생가능한에너지생산과활용에다양한정책사업을추진하고있으며, 국가적인차원에서 5년주기로거듭된신재생에너지기본계획을수립하고있다 (MOTIE, 2014). 이러한정책가운데정부는 2010년대초부터정부주도사업으로저탄소녹색마을, 친환경에너지타운등을조성하여환경기초시설및비선호시설등에대한문제해결과신재생에너지공급을추진하여왔다. 그리고여러정부부처와지자체도관련친환경에너지타운종합계획수립및친환경에너지타운의융복합신재생에너지활용모델을지원하기시작하였다 (Wang and No, 2014). 조사된해외에서신재생에너지를활용하는주택단지사례들의목적은에너지소비감소뿐만아니라주민의삶의질개선에있으며, 이러한시스템은주변자연경관과어우러져마을의주택들과이질감을갖지않도록설치한다 (Rhee et al., 2011). 신재생융복합형친환경에너지타운은여러신재생 에너지간융복합설비구축을통하여생산전력은판매하고, 열은자체사용하는형태로서국내에서도고창및진천등여러곳에서시도되었다 (KIER, 2014, 2015). 신재생에너지가운데보어홀지중열저장 (borehole thermal energy storage: BTES) 기술은열교환기가지중에매설되므로주변환경과조화로운설계가가능하며, EPA(L Ecuyer et al., 1993) 보고서에서도가장친환경적인청정에너지활용형태로서건물냉난방을위해환경에대한위해성을최대한으로줄일수있다고하였다. 특히겨울난방수요가큰경우여름철잉여의태양열을지중에축열하여그축열된열을겨울에이용함으로써높은성능의시스템을구성할수있다. 본연구에서는국외에서성공적으로진행된 BTES 를활용한 3가지사례들을조사하여친환경에너지타운의설계및건설을위한관련시스템및관리현황을파악하고자하였다. 조사된해외프로젝트사례로서캐나다의 ADEU(Alexandra District Energy Utility: City of Richmond, 2014), DLSC(Drake Landing Solar Community: Leidos, 2014) 및덴마크 Brædstrup Solpark 시스템 (Sørensen, 2013) 을분석하였다 (Table 1). Table 1. Summary of three hybrid thermal energy supply systems with borehole thermal energy storage (BTES) in Canada and Denmark (City of Richmond, 2014; Flynn and Sirén, 2015; PlanEnergi, 2013) Plant name/location (Project supervisor) First year of operation BHEs(depth, m) and other sources Buildings ADEU, Canada (City of Richmond) 2012 July 726(76) BHEs with single PE U-tube and natural gas boiler backup 1200 Residential Homes + buildings DLSC, Canada (NRcan) 2007, June 144(35) BHEs with single PEX U-tube with seasonal thermal energy storage and solar collectors(2,242 m 2 ) 52 Residential Homes Brædstrup, Denmark (Brædstrup fjernvarme) 2012 48(45) BHEs with double PEX U-tube with seasonal thermal energy storage and solar collectors (18,600 m 2 ) et al. 1500 Residential Homes
친환경에너지타운에서보어홀지중열저장 (BTES) 활용융복합열에너지공급시스템사례연구 69 2. 보어홀지중열저장 (BTES) 최근신재생에너지간또는다른열원과융합을통하여최대한의효율을높임으로써초기투자비저감과투자비회수기간단축에대한사업들이주목받고있다. Qi et al.(2014) 에의하면최근융합형지열히트펌프시스템 (Hybrid ground source heat pump system) 은지열히트펌프를중심으로태양열, 보일러, 전기히터, 폐열, 냉각탑및지중축열등다양한열원을접목하는기술로서유럽, 북미및중국등세계적으로급속히확산되어왔다. 이러한융합열원에의해설계된시스템은마을이나지역단위주거지역에서사계절안정적인열에너지원으로활용할수있으며, 경제적이고효율적인설계가가능하다 (Kim et al., 2016; Nam and Gao, 2014; Rad et al., 2013). 친환경에너지타운은각지역의에너지생산및활용특성에따라일부또 는전체를신재생에너지원들을개발하여이용한다. 그런데경제적으로생산한전기를저장하기어렵거나또는시간적으로에너지생산량변동폭이커서안정적인공급이이루어지기어려운경우, 최근신재생에너지태양열지열융복합형태로여름철잉여태양열에너지를지중에저장하여이용하는축열시스템적용이가능하다 (Oh and Nam, 2015; Pinel et al., 2011). 지중축열방식으로는보어홀지중열저장 (BTES: Borehole Thermal Energy Storage), 대수층 (ATES: Aquifer Thermal Energy Storage), 저수조 (WTS: Water Tank Storage) 등의형태가있다 (Fig. 1). 조사된방식들은지역여건이나설계방법에따라성능및비용차이가있을수있으나저수조축열시스템기준으로물 /m 3 에해당하는여러형태의축열시스템설치비용에서대수층과 BTES를이용하였을경우가가장경제적인것으로나타났다 (Fig. 2). 설치비에서축열부피당 Fig. 1. Scheme of a central solar heating plant and underground thermal energy storage concepts (Pavlov and Olesen, 2011). Fig. 2. Plot of the installation cost at several borehole thermal energy storages(sibbet and McClenahan, 2015).
70 심병완 Fig. 3. The relationship between hydraulic gradient and hydraulic conductivity with contour lines of specific discharge and typical hydraulic conductivities according to the rock and soil types (Ferguson, 2015). 단가는대략 10 ~ 35 $/m 3 로추정되며, 이중에서 BTES 축열시스템은지반내수리지질및열물성등의조건에따라경제적인설계가가능하다. 지중축열시스템은일반적으로지중내지하수유속이느리고, 열을저장하는범위내지반의열전도도가높은경우에유리하다 (Ferguson, 2015). Fig. 3은지반내수리전도도와수리경사, 그리고암종별로수리전도도의차이를도시화한것으로서대상지반을선정할때설계단계에서지질조건과수리적특성파악이선행되어야한다. 국내지질은국토의넓은면적이낮은수리전도도의화강암이나변성암지대가널리분포하고있으므로 (Reedman and O o m, 1975), 수리지질특성들을잘파악하면지중축열에유리한지역을찾을수있다. 이러한지하수유동은관측공에서의지하수위측정및양수실험, 지질조사등을통하여파악이가능하며, 일정범위의그라우팅실시등의지반개량을통하여원하는축열환경을만들수도있다 (Gehlin, 2016). 3. 국내현황친환경에너지타운은 2014년부터주로환경부주관 (16개소) 으로실시되어왔으며, 그후산업부 (6개소), 과기정통부 (1개소) 및농림부 (1개소) 등총 24개지역에서사업이선정되어진행중이다 (Chang et al., 2014; KIER, 2014; ME, 2017). 초기시범사업으로강원홍천 ( 환경부 ), 광주광역시 ( 산업부 ), 충북진천 ( 미래부 ) 이추진되었으며, 국내사업유형은크게매립지형, 폐기물처리형및신재생융복합형으로나눌수있다. 그리고환경부에서진행된많은사업들은매립지형또는폐기 물처리형으로폐기물에너지화사업에가까운경우가대부분을차지한다 (Chang et al., 2014). 앞으로는쾌적한주거환경을위한신재생융복합형친환경에너지타운에도많은수요가있을것으로예상되며, BTES를활용한국내사례는아직고창군의태양열과지열을활용하는에너지자립형주택단지이외에는찾아보기어렵다. 국내사례에서는친환경에너지타운개발로서지역에너지전환의명확한중장기비전과목표설정이미미하거나환경성문제해결에어려움을가지고있다. 그리고아직정부및지자체의협조나도움없이기업차원에서대단위친환경에너지타운을개발하기는매우어려운것으로판단된다. 이러한문제를해결하기위해서는지역사회의수요에적합한경제적개발시스템구축과더불어단계적사업추진을지원하기위한중간지원조직이요구된다 (Chang et al., 2014). 또한주민친화적개발및시스템운영을위해서는규모지향적개발보다는장기적인관리시스템구축과운영안정성확보와같은프로그램이추가되어야할것으로사료된다. 4. 국외사례 4.1. ADEU(Alexandra District Energy Utility, 캐나다 ) 4.1.1. 프로젝트개요리치몬드시는 2014년인구가약 20 만명이며, 2041 년약 28 만명까지확대된다고예상하여도시를계획하였으며, 이에따른지역에너지보급시설로서 ADEU 프로젝트를수행하였다. 시에서는신재생에너지시스템
친환경에너지타운에서보어홀지중열저장 (BTES) 활용융복합열에너지공급시스템사례연구 71 을지속적으로확대및보급하여화석연료사용저감과 2020년까지 33%, 2050년까지 80% 의온실가스배출감소목표를가지고있다 (City of Richmond, 2017). ADEU는대규모 BTES 시스템을이용한지역냉난방공급시스템으로서지열히트펌프기반의지역냉난방공급시스템을에너지전문사에의하여설계되었으며, 2012년에 1단계완료와 2015년 3차확장을마무리하였다 (City of Richmond, 2010). 이시스템의에너지센터건물은주변자연경관및마을과조화롭게어울리도록설치되어있다. 그리고주민친화적인설계로건물외부에서내부시설을볼수있도록하여주민들의관심을지열및청정에너지활용에긍정적인방향으로이끌고있다. 4.1.2. 시스템구성 ADEU는현재 5개의대형공동주택 (1200 가구규모 ) 과하나의상업용빌딩에대한냉난방에너지를공급하고있다. BTES는 76m 심도의수직밀폐형타입이 726개공이설치되어있으며, 각수요처와네트워크파이프로연결되어공급대상건물에냉난방에너지를공급하고있다 (Fig. 4). 미래냉난방수요를충족하기위한확장을위해추가지열시스템으로개방형, 밀폐형등의타입이계획되어있다 (City of Richmond, 2014). 시에서는 ADEU 지역난방범위와연결방법을매뉴얼로구성하였으며다음과같은 3개의시스템들로이루어져있다 (City of Richmond, 2016). 1. Central Energy Plant(CEP) the energy source, 2. Distribution Piping System(DPS) the distribution network, 3. Energy Transfer Stations(ETS) the building interface. CEP는에너지생산시설로서 BTES 필드, 보일러및쿨링타워, 그리고에너지분배를위한펌프, 파이핑과컨트롤러등을포함한다. 연결된건물들의냉난방부하에의하여 CEP는지중열교환기를통하여난방이나냉방모드로운영되며, 쿨링타워는추가적인피크부하에대한백업시설로이용된다. DPS는파이프네트워크로서이용자들에게열에너지가공급되는시스템이며, 물과프로필렌글리콜 (Propylene glycol) 용액이순환수로이용된다. ETS는각건물에설치되어있으며, 송수용파이프, 분배시스템과건물의 HVAC 시스템및기타레귤레이터, 조절밸브및센서류들로구성되어에너지사용량에대한과금및최적화에이용된다. 각시스템은자동화된디지털제어시스템으로서지속적인모니터링으로소요에너지를감소시키며, 여름에는열을지중에저장하고겨울에이용할수있도록운영하고있다 (Ruffen, 2014). 4.1.3. 규정및관리리치몬드시는지역에너지공급에대하여시설설치와유지및열에너지공급에대한계측자료를근거로요금을제시한다. 유량및적산열량, 피크부하및온도모니터링등과에너지미터를이용하여중앙서버에전송된자료들을활용하여에너지요금을산정한다 (LuluIsland Co., 2016). 에너지사용요금은리치몬드시에서연도별기준으로과금되며, 그내용은시에서만든조례 Bylaw 8641(City of richmond, 2010) 에규정되어있다. 이조례를통하여리치몬드시에서는 Fig. 4. Schematic of the Alexandra district energy systems works (modified from LuluIsand Co., 2016).
72 심병완 Alexandra 지역의다양한주택및건물들에급탕및냉난방에너지를공급하는서비스를제공하고있다. 4.2. DLSC(Drake Landing Solar Community, 캐나다 ) 4.2.1. 프로젝트개요 DLSC는캐나다앨버타주 Okotoks에위치하며, 태양열과지열을이용한하이브리드중앙집중식난방시스템으로서 Natural Resources Canada(NRCan) 와캐나다연방정부및앨버타주에의하여지원되었다 (Wamboldt, 2009). 전체 52 가구가연평균난방의 90% 정도를이시스템으로이용하며, 나머지는천연가스백업시스템을이용한다 (Sibbitt, et al., 2015). BTES 및전체설계는 TRNSYS 모델이이용되었으며, 여러시뮬레이션을위해다양한기후및토양등의자료가이용되었다 (Flynn and Sirén, 2015). 초기설계및건설을위해복합적인열원및방법들을이용하는데관련분야의여러전문회사및주택개발업자가참여하였다 (Zaidi, 2009). 4.2.2. 시스템구성 DLSC 냉난방시스템은크게 3 가지로태양열집열기, 단기축열탱크가있는에너지센터, 그리고 BTES 로이루어져있다 (Fig. 5). 겨울에는태양열활용이제한적이라이러한단점을보완하기위하여지중축열시스템을이용한다. 개당 2.45 1.18m인크기의태양열집열기 800개가주차장지붕에설치되어있으며, 태양열로부터얻은에너지는에너지센터내의단기축열탱 크에저장된다. 여름철이송된순환수에의하여 BTES 로장기적으로지반에열이축적되고, 겨울철에는난방을위하여축열된지반의열을재사용한다 (Sibbitt et al., 2012). 에너지센터는 120m 3 크기의두개의단기축열조, 백업가스보일러및기계장비로는펌프, 열교환기및컨트롤러들로이루어져있다. 그리고태양열패널의루프, 지역난방루프및지중열교환기루프가이곳에연결되어있으며, 지중열교환기는 144 개 (37m 심도 ) 로이루어져있다. 여름에는지중열교환기파이프내순환수온도가약 80 o C 내외로상승하는고온축열방식으로설계되어있으며, 전체 BTES 체적은 34,000m 3 으로서방사상형태로연결된 6개의공들이하나의시리즈로구성된다. 고온축열방식은캘거리와같이겨울이길고추운기후지역에서다소유리한데, 히트펌프를이용하지않고직접순환수를이용하므로초기비용이다소저렴하지만, 백업용장치로서소규모천연가스보일러같은시설이요구된다. 지반은표토층이 4.1m로서실트질클레이및자갈과모레로구성되어있으며지하수위는지표하 2.6 ~ 5.9m 사이에있다. 지표온도는연평균 5 o C이며, 여름에는최고 37 o C, 겨울에는최저 35 o C까지변화한다 (Catolico and McCartney, 2016). 4.2.3. 규정및관리 DLSC의에너지순환과정은웹사이트에서조회가가능하게하여시스템운영의신뢰도를높이고있으며, 각종모니터링자료도제시하고있다 (Fig. 6). 파이프 Fig. 5. DLSC conceptual model of the solar seasonal storage and district loop with borehole thermal storage field (Sibbitt, et al., 2015).
친환경에너지타운에서보어홀지중열저장 (BTES) 활용융복합열에너지공급시스템사례연구 73 Fig. 6. The captured figures on the conditions of DLSC energy flow at www.dlsc.ca/animation.htm on March 2(above) and August 22(below), 2017. 및지중열교환기곳곳에설치된센서들로부터지중열교환기순환수, 태양열순환수, 지중열교환기중심부및가장자리온도, 외기온도, 순환수방향및가정내공급량등자세한정보를실시간으로파악할수있다. 분단위로축척된모니터링자료들은월간및연간리포트로 NRCan와 Town of Okotoks에보고된다. 이것은에너지공급시스템성능자료를매주집계하여, 태양열패널에서획득한에너지및 BTES에축열되는양과사용되는양을확인할수있다. 각가정은대략 천연가스를이용한난방비정도의비용으로에너지를이용하고있으며, 남는수익은운전비용과 NRCan에서모니터링과분석을담당하는비용으로지출된다 (leidos, 2014). 4.3. Brædstrup Solpark (Brædstrup, 덴마크 ) 4.3.1. 프로젝트개요덴마크는자연과인간의공존을같이생각하는적극적인사회적인식으로신재생에너지활용이매우활발
74 심병완 하다. 따라서현재의경제적인편익을추구하기보다여러세대에걸쳐미래자연과환경을같이고려한도시를설계하는개념을가지고있으므로지열시스템과융복합된지역난방프로젝트의성공이가능한것으로판단된다 (Brædstrup Fjernvarme, 2017). 덴마크지역난방시스템의하나인 Brædstrup Solpark는 Brædstrup Fjernvarme 지역난방회사에서운영한다. 태양열축열방식의 BTES 및다양한열에너지공급시스템으로이루어져있으며항구도시인 Aarhus의서편에위치한다. 전체적인개념은태양열, 지중축열및히트펌프활용으로기존천연가스플랜트를대체하여화석연료의사용을줄이는데목적이있다. 다양한열원으로구성된지역난방을운영할수있으므로에너지가용성및가격면에서유리하다 (PlanEnergi, 2013). 1단계는 2007 년에완료되었으며, 태양열과천연가스로연간 40,000MWh의열공급시설을만들었다. 4.3.2. 시스템구성전체태양열패널면적은 18,600m 2 이며난방면적은 296,378m 2 이다. 19,000m 3 의지반내에설치된 BTES 그리고 5,500m 3 와 2,000m 3 의 2개의버퍼탱크, 보일러, 열병합발전기, 히트펌프로구성되어있다 (Fig. 7). 이시스템은태양열계간축열을위한 BTES, 파워플랜트, 보일러, 풍력, 우드칩을이용한다양한복합열원을이용할수있도록설계되어있다. 지역난방네트워크는전체 27.9km로서서비스파이프라인길이는 21.1km이며, 지반의평균지중열전도도는 1.4W/mK이고모두 48개의보어홀로구성되어있다 (Fig. 8). 지중열교환기 Fig. 7. Brædstrup energy flow diagram (modified from Schmidt, 2016). Fig. 8. Layout of the piping and the profile of BTES in Brædstrup Solpark (modified from PlanEnergi, 2013).
친환경에너지타운에서보어홀지중열저장 (BTES) 활용융복합열에너지공급시스템사례연구 75 는 double U-tube 형태이며, 보어홀간간격은 3m, 심도는 45m이다. 주입수최고온도는 80 o C 내외이며, 16개씩한조로연결된보어홀스트링 6개로구성된다 (Tordrup, 2017). 3단계확장계획에서는태양열집열기를 50,000m 2 까지추가확장하며, BTES 체적도 200,000m 3 으로확대할계획이다 (Sørensen et al., 2013). 4.3.3. 규정및관리 Brædstrup Solpark는 Brædstrup Fjernvarme 지역난방회사에서운영하며, 매년축적된모니터링된자료를바탕으로연간에너지사용리포트를발간하여웹페이지에게시하고있다 (Brædstrup Fjernvarme, 2017). 여기에서는연도별손익계산서, 에너지요금및 A/S 등의기술적인사항들을포함하며다양한정보를수집하여소비자에게에너지사용료를부과한다. 회계연도말에난방연도의소비자열량계및소비량은 MWh로계산되며, 과금시스템은관리회사자체의기술적요소와경제적 법적규정등을통하여설계된다. 5. 결론본연구에서는국내친환경에너지타운현황을검토하고해외에서성공적으로수행된 3가지사례로서캐나다와덴마크의 BTES 융합친환경에너지타운을조사하였다. 캐나다는석유및천연가스등의에너지자원이풍부한나라임에도불구하고 2000년대초반부터화석연료사용감소를위해신재생에너지를적극적으로개발하고이를지역난방에까지적용하고있다. 캐나다지자체와연방정부는이러한시스템을지원하기위한정책과관리규약등을만들었으며, 이를통하여에너지전문업체및주택개발업체등과협력으로친환경에너지타운조성에지속적인투자를하고있다. ADEU와 DLSC는이러한정책과제도적인환경을바탕으로만들어진성공적인사례이며, 기후조건과도시환경등을복합적으로고려하여거주자들에게효율과경쟁력있는에너지요금을제시한다. 그리고덴마크 Brædstrup Solpark는이지역에유리한다양한에너지원을이용하여경제적인요금으로난방에너지를공급하고있으며, 태양열및지열시스템등의조합을이용한보다많은주택에청정에너지공급을계획하고있다. 조사된친환경에너지타운은성공적인운영및확장이장기적으로이루어져왔으며, 이러한성공요소는지자체와관리업체의신뢰성있는협력과관리제도및정책을통하여가능한것으로판단된다. 국내 개발여건을고려하면 BTES를이용한친환경에너지타운개발은부지유용이가능한도심지와농어촌지역에서경제성과환경성을충분히확보할수있을것으로판단되며, 다른열원들과의조합도유리한것으로사료된다. 그리고신뢰성있는시스템구축을위해서는정부나지자체의제도적인지원및장기적인에너지계획수립이필수적이다. 아직민간부분의투자나개발이매우미미하지만현재이루어지고있는다양한시범사업들의성공을통하여국내에적합한시스템개발과더불어시장이확대될것으로사료된다. 사 사 이연구는한국지질자원연구원기본사업 (KIGAM basic research fund) 기후변화대응지하수 / 지열자원확보및생태보전융합기술 (Terra-4G) 개발 과제지원을받아수행되었습니다. References Brædstrup Fjernvarme (2017) Brædstrup District Heating, http://www.braedstrup-fjernvarme.dk. Catolico, N., Ge, S. and McCartney, J. S. (2016). Numerical modeling of a soil-borehole thermal energy storage system. Vadose Zone J., v15, p.1-17. Chang, Y.B, Lee, J.P. and Cho, B.Y. (2014) Designing New Policy Approaches to Facilitate Energy Transitions in Local Communities in Korea, STEPI report 2014-03. City of Richmond (2010) Alexandra District Energy Utility Bylaw No. 8641, 35p. City of Richmond (2014) Technical report 10-6600-10-02/ 2014-Vol 01 (Alexandra District Energy Utility Expansion Phase 3). City of Richmond (2016) Alexandra District Energy Utility - A Guide for Connection to District Energy. City of Richmond (2017) Energy Action in Richmond Community Energy and Emissions Plan. Ferguson, G. (2015) Screening for heat transport by groundwater in closed geothermal systems. Groundwater, v53, p.503-506. Flynn, C. and Sirén, K. (2015) Influence of location and design on the performance of a solar district heating system equipped with borehole seasonal storage. Renewable Energy, v81, p.377-388. Gehlin S. (2016) Advances in Ground-Source Heat Pump Systems (Rees, Simon, ed.) - Borehole thermal energy storage. Woodhead Publishing, p460. KIER (2014) Development of the Environment-friendly Zero Energy Town based on the Renewable Energy, KIER-B42426, 252p. KIER (2015) Master-plan for demonstration construction of the eco-friendly energy town and a basic design of optimized hybrid new and renewable energy system,
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