FACT SHEET Assessing the Feasibility of a Geoexchange System for your Agricultural or Agri-Food Operation

Transcription

1 FACT SHEET Assessing the Feasibility f a Geexchange System fr yur Agricultural r Agri-Fd Operatin Geexchange systems are an increasingly cmmn technlgy used t prvide efficient, renewable heating and cling fr buildings and industrial prcesses. Geexchange systems use a grund heat exchanger, ne r mre grund surce heat pumps, and an interir distributin system t mve heat t and frm the grund and a building. Several factrs affect the technical feasibility and financial viability f geexchange systems in agricultural and agri-fd peratins. These include: base-case fuel csts; available grund heat exchanger ptins; heating and cling lad duratin; and existing interir distributin systems. This fact sheet discusses these factrs, and prvides guidance fr hw t assess whether geexchange heating r cling might benefit yur agricultural r agri-fd peratin. This fact sheet is based n results frm the Geexchange Feasibility in Agricultural and Agri-fd Operatins Benchmarking Study. This study is available at energy/ and includes five individual feasibility studies and site assessments f Agricultural peratins. Funding fr this prject was prvided by Grwing Frward, a federal-prvincial-territrial initiative. Characteristics f Prfitable Geexchange Systems Base-case Fuel Csts Geexchange systems usually invlve switching a large prtin f annual energy csts away frm fssil fuels t electricity that drives the heat pump. Therefre, the cst f fssil fuels and electricity has a strng effect n prject prfitability. Higher cst base-case fuels, such as prpane, are mre likely t lead t prfitable geexchange systems, while lwer cst base-case fuels, such as natural gas, are less likely t lead t prfitable geexchange systems. 1 Ptential energy cst savings can be estimated using the frms n page 4 f this fact sheet. 1 See Appendix B f the Geexchange Feasibility in Agricultural and Agri-fd Operatins Benchmarking Study fr the range f energy prices in affect at the time f the study.

2 Available Grund Heat Exchanger Optins Because f the tectnic and glacial histry in B.C., grund cnditins are mre variable than virtually anywhere else n Earth. This is imprtant because the gelgical attributes f a lcatin can significantly affect the csts and perfrmance f the grund heat exchanger prtin f a geexchange system. Fr example, while ne site may have cnditins that can accmmdate a lw-cst, high perfrmance grund heat exchanger ptin, a nearby site may have cnditins with limited pprtunities that can nly accmmdate a high-cst, lw perfrmance grund heat exchanger. As a result, the cst fr the same geexchange capacity can vary by mre than an rder f magnitude frm ne site t anther, highlighting the key rle site specific characteristics can play in prject ecnmics. Grundwater Open-lp Grund Heat Exchangers: In certain rare settings with highly prductive aquifers, very high grund heat exchange capacity can be achieved at a relatively lw cst. Where these cnditins exist, geexchange systems can ften be prfitable ver a brad range f base-case fuel csts, heating and cling requirements, and existing distributin systems. In sme circumstances an wner may already have a high capacity water well in place that culd be used t supply a geexchange system. These cnditins can be very prfitable because a significant prtin f the installatin cst is eliminated. It warrants nting that care must be taken fr this type f system t ensure the water quality is cmpatible fr heat exchange and the prductin f sufficient grundwater is sustainable ver the lng-term. Hrizntal Clsed-Lp Grund Heat Exchangers: Agricultural and agri-fd peratins ften have large pen land areas suitable fr a hrizntal grund heat exchanger. The grund cnditins in the upper 4ft t 10ft can significantly influence cnstructin csts fr this ptin. In settings with fine-grained sils free f stnes, very inexpensive hrizntal grund heat exchangers can ften be installed with little surface disturbance using a chain trencher. Trenching with an excavatr is als cmmn, with installatin csts varying depending n trench wall stability, presence f cbbles and bulders, r ther cnditins that affect the excavatr time required. In sme settings with uncnslidated lse sils, the mst cst effective apprach is t strip a larger single excavatin with a dzer and install a mat f piping rather than excavate multiple trenches. Vertical Clsed-lp Grund Heat Exchangers: In sme cases, a vertically-bred grund heat exchanger may be the nly ptin available. In these cases it is imprtant t evaluate grund cnditins carefully. In B.C. s diverse gelgical settings, the csts assciated with installing a vertical brehle grund heat exchanger can vary significantly and is ften the determining factr in a prject s prfitability. Installed cst is dependent n the ease f drilling and installing the heat exchange tubing, and the thermal exchange prperties f the sil/bedrck that is encuntered. Gd cnditins ccur where straightfrward drilling techniques can be used and sils

3 with gd thermal prperties, such as shallw bedrck, allw shrter ttal brehle length. Pr cnditins ccur where the bedrck ccurs at an awkward depth that requires different drilling techniques t cmplete shallw and deeper segments f each brehle, r where drilling is therwise challenging r unusually expensive (e.g. highly fractured bedrck, the presence f large bulders in uncnslidated sils, etc.). Lw thermal cnductivity sils such as dry sands and gravels can require cnsiderably lnger ttal bre length, thugh the lnger bre length required in these settings may be ffset by the suitability f less cstly drilling methds. GeExchange BC, a nn-prfit industry assciatin, has develped prfessinal guidelines t address the imprtant step f evaluating ptential grund heat exchanger pprtunities (Prfessinal Guidelines fr Geexchange Systems in British Clumbia - Part 1 Assessing Site Suitability and Grund Cupling Optins; Geexchange BC, 2007). Heating and Cling Lad Duratin A cmmn feature f prfitable geexchange systems is a lng duratin heating r cling lad. This ccurs because capital equipment can nly generate a return n investment when perating. Shrt duratin, high intensity lads are the least prfitable because the necessary high capacity equipment nly perates fr a limited number f hurs in a typical year, and therefre cannt prduce enugh savings t vercme high installatin csts. Facilities with lnger duratin heating requirements, including relatively cntinuus prcess heating requirements and/r unique heating lads that extend int the summer, are the mst likely t be prfitable. Because geexchange systems can prvide bth heating and cling, lng run times can als ccur fr facilities that require bth winter heating and summer cling. Facilities that have cncurrent heating and cling lads can ften recver the heat being rejected in the cling prcess and use it t ffset heating requirements. Heat recvery frm cncurrent cling lads is ften very prfitable. Interir Distributin Systems In retrfit applicatins, the existing heating and cling distributin system may r may nt be easily adapted t a new geexchange system. Extra csts t mdify existing distributin systems, r t install new distributin systems can lwer verall prject prfitability. Additinal csts are ften required t mdify existing heating and cling systems that cnsist f many small distributed unit heaters r rf tp units. Geexchange systems are ften mst easily adapted t existing ht water heating distributin systems and central biler r furnace systems. It is imprtant t recgnize that mst geexchange systems cannt generate the high temperatures that cnventinal bilers can. Lwer temperature systems like radiant flrs are ften ideal candidates fr direct cnnectin t a geexchange system with n additinal distributin system csts. New cnstructin ften prvides mre flexibility than retrfit situatins fr designing a distributin system with geexchange in mind.

4 Estimating Ptential Savings A quick estimate f the ptential energy csts savings that culd be achieved with a geexchange system can be calculated with the frmulas belw. These calculatins are based n a number f simplifying assumptins, but will prvide a rugh estimate fr wners t determine if the ptential savings frm a geexchange system warrant further evaluatin. Ptential Geexchange Savings vs. Natural Gas Hybrid System with geexchange serving 70% f annual lad and natural gas serving 30% 1) Multiply annual gas cnsumptin: by 48.7 t estimate annual GSHP energy cnsumptin: Current annual cst f natural gas: $ (A) GJ (ttal frm utility bills) kwh (B) 2) Multiply (B) by yur current electrical rate in $/kwh t estimate annual Cst f Electricity: 3) Multiply (A) by 0.3 t estimate aeduced annual cst f gas: $ (C) $ (D) 4) Add C and D t estimate the annual cst with hybrid geexchange: $ (E) 5) Subtract E frm A t estimate the Ptential Savings frm Geexchange: $ (Assumes natural gas seasnal heating efficiency f 80%, GSHP average COP f 3.2) Ptential Geexchange Savings vs. Prpane Hybrid System with geexchange serving 70% f annual lad and prpane serving 30% 1) Multiply annual prpane use: by 1.2 t estimate annual GSHP energy cnsumptin: Current annual cst f prpane: $ (A) Litres (ttal frm utility bills) kwh (B) 2) Multiply (B) by yur current electrical rate in $/kwh t estimate annual cst f electricity: 3) Multiply (A) by 0.3 t estimate reduced annual cst f prpane: $ (C) $ (D) 4) Add C and D t estimate the annual cst with hybrid geexchange: $ (E) 5) Subtract E frm A t estimate the Ptential Savings frm Geexchange: $ (Assumes prpane seasnal heating efficiency f 80%, GSHP average COP f 3.2)

5 Readers shuld nte that peratins with simultaneus heating and cling needs may achieve significantly higher energy cst savings than estimated by the frmulas abve. Optimal sizing f a geexchange system may als lead t a higher r lwer prprtin f the annual lad being prvided by the heat pump than has been assumed abve. Regulatry Apprval Prcess, Bdies and Agencies Geexchange systems must fllw the same standard regulatry apprval and permitting prcesses assciated with cnventinal heating and cling systems. These include thse required by the Electrical Safety Authrity, WrkSafe BC, BC Building Cde, and building permit requirements f the lcal authrity having jurisdictin. There are n regulatry apprvals r permitting prcesses related specifically t geexchange systems. Hwever, excavatin and drilling f grund heat exchangers must fllw safety and envirnmental regulatins prtecting grundwater, surface water bdies, and ther envirnmentally sensitive areas as listed belw. Prducers shuld be aware f the fllwing regulatins and legislatin particularly relevant t the cnstructin f grund heat exchangers: BC Grundwater Prtectin Regulatin Requires the use f registered water well drillers (fr clsed lp vertical brehle systems and grundwater pen-lp systems) and registered pump installers fr grundwater systems Specifies apprpriate measures t prtect grundwater aquifers Cmmn prperty rights must be respected including utility rights f way and ther easements BC Water Act and federal Fisheries Act Require apprval fr any activities in and abut water bdies and the disturbance f fish habitat

6 Predicting Site Suitability Given the many variables that influence the prfitability f geexchange systems, it can be challenging t determine the suitability f geexchange fr a particular applicatin withut a detailed site-assessment. Hwever, based n the cmmn characteristics f prfitable scenaris discussed in this Fact Sheet, wners can use the adjacent graphics t judge the likelihd that a geexchange system will be suitable at their peratin. Sme peratins may have all the features f prfitable systems listed under High Likelihd f Suitability. These peratins are quite likely t benefit frm a geexchange system and wners are encuraged t take further steps t evaluate the pssibility f using geexchange technlgy at their site. Similarly, sme peratins may have all the features f unprfitable systems listed under Lw Likelihd f Suitability and likely d nt warrant further cnsideratin f geexchange withut ther additinal infrmatin t suggest therwise. The majrity f agricultural peratins will have a cmbinatin f characteristics frm bth lists. Fr these peratins, wners shuld weigh the benefits f the ptential energy cst savings calculated n the previus page against the mix f features at their site. Operatins with the ptential fr cnsiderable savings and at least ne f the features listed under High Likelihd f Suitability warrant a discussin with a prfessinal t determine if a detailed evaluatin is justified. Lng heating seasn Prcess heating Summer heating Bth heating and cling High capacity well Large pen area Easy trenching Gd drilling cnditins Shrt heating seasn CO2 enrichment frm cmbustin Infrequent r n prcess heating Limited space Large bulders Challenging drilling cnditins Lng Lad Duratin Lw Cst GHX Optins Shrt Lad Duratin High Cst GHX Optins High Likelihd f Suitability Lw Likelihd f Suitability High Cst Base Case Fuel Existing Distributin System Lw Cst Base Case Fuel Existing Distributin System Prpane Heating il Electricity Radiant flr heat Ht water radiatrs r fan cils New cnstructin Natural gas Lcal bimass Other lw cst fuels Distributed heaters r rf tp units Electric basebards Temps abve 50 C Fr mre infrmatin cntact Clleen Clwell Ministry f Agriculture Clleen.Clwell@gv.bc.ca