Non-Treaty Storage Utilization System Modeling Summary

Transcription

1 Nn-Treaty Strage Utilizatin Nn-Treaty Strage Utilizatin 1.0 Operatinal Mdeling 1.1 Intrductin BC Hydr is currently examining fur scenaris fr utilizatin f Mica Nn-Treaty Strage. BC Hydr simulated these perating scenaris using several interrelated cmputer mdels f the Clumbia River hydrelectric facilities. The Water Licence Requirements grup in BC Hydr is then able t use the mdelling results and develp perfrmance measures t cmpare hw well each scenari perfrms in satisfying the Clumbia River Water Use Plan bjectives, and ther system perating bjectives. 1.2 Mdelling Operating Scenaris BC Hydr uses several Pwer Operatins Mdels t simulate peratins f the Clumbia River hydrelectric facilities accrding t the criteria develped fr each Nn- Treaty Strage scenari. These simulatin prgrams are the same mdels (r updated versins) that were utilized in the Clumbia Water Use Planning prcess, and are cmmnly utilized in BC Hydr lng range planning studies. Fr each perating scenari, the Pwer Operatins Mdels prvide statistics fr reservir elevatins, dam discharges, river flws and value f pwer generatin fr the years f simulated flw peratin. These utputs serve as inputs t envirnmental mdels t calculate perfrmance measures fr each scenari. Figure 1.1 illustrates the mdelling prcess fr Nn-Treaty Strage studies, which is generally cnsistent with that used in the Clumbia Water Use Plan. 1.3 Clumbia River Treaty Discussin n the integratin f the Clumbia River Treaty int system mdeling is prvided in Sectin f the Clumbia Water Use Plan Cnsultative Cmmittee Reprt (July 2005). Over a number f years, BC Hydr has annually negtiated nn-pwer agreements with the US, including flw management agreements fr: Rainbw trut spawning in the Canadian Clumbia River t maintain river levels at Nrns Creek Fan between 1 April and 30 June. Whitefish spawning, which allws strage at Kinbasket and Arrw Lakes reservirs during January t reduce Arrw utflw by abut 20 kcfs fr enhancement f whitefish spawning. These agreements are cnsidered by bth BC Hydr and their US cunterparts t be critical perating agreements, that are required t meet envirnmental bligatins n bth sides f the brder. As such, peratinal adjustments t prjected Treaty peratins were made fr all Nn-Treaty Strage scenaris that wuld reflect a cntinued presence f these agreements in future years. 1

2 Nn-Treaty Strage Utilizatin Prpsed Nn-Treaty Strage Scenaris Figure 1.1: Nn-Treaty Strage scenari mdelling prcess 1.4 Pwer Operatins Mdels As in the Clumbia Water Use Plan, the analyses f perating scenaris were carried ut by three different but interrelated mdels f the Clumbia River system. These mdels included: 1. HYSIM, which mdels the verall peratins f the BC Hydr system system, including all reservir elevatins, dam releases and river flws n the Clumbia River. 2. GOM, which is used t prvide detailed mdeling f flws immediately belw Revelstke Dam. 3. Excel Spreadsheet mdels that mdel: Nn-Treaty Strage peratinal scenaris. Flw adjustments belw Hugh Keenleyside Dam, which cnsidered changes t Clumbia River Treaty flws, driven by nn-pwer agreements. Principle requirements r inputs fr the mdels included: Hydrelectric facility cnstraints based n physical limits (e.g., turbine capacity, reservir capacity, spillway rating), licensing, integrated electrical system requirements, and Treaty bligatins. Lng standing critical perating agreements t manage BC Hydr and US envirnmental bligatins. These agreements have been signed annually since 2

3 Nn-Treaty Strage Utilizatin the mid-1990 s, and have a very high likelihd f cntinuing t be signed in future years. Likely peratins at Arrw under the Libby Crdinatin Agreement which is an evergreen agreement that prvides the US with flexibility t meet EPA bligatins at Libby, and prvides a mechanism fr BC Hydr t recup pwer lsses assciated with this peratin. Mdificatins t peratins that wuld be reflective f the NTSA scenari that is being cnsidered. Variatin in snwpack levels, freshet timing and precipitatin events result in different reservir elevatins and facility discharges between years. These variatins are reflected in different discharge regimes within a given scenari as the Operatins Mdels attempted t ptimize the value f pwer generatin. In the case f Kinbasket, reservir strage capacity is sufficient t influence next year peratins by supplementing r withhlding actual inflws using strage. This characteristic is unique t a multi-year strage reservir, in that actual discharge is tied t bth annual inflw and previus year strage and discharge decisins. Fr example, tw successive drught years may have large implicatins n hw the hydrelectric prject behaves in the third year. The primary utput f the pwer peratins mdels is a set f data describing reservir elevatins and flw releases thrugh time fr each facility. These utputs were then used as inputs t generate perfrmance measures based n flw and/r reservir elevatins and t estimate pwer generatin. 2 NTSA SCENARIO MODELING BC Hydr is cnsidering fur scenaris fr the utilizatin f Nn-Treaty Strage at Mica. In all scenaris, mnthly usage f the strage (strage and release) has been restricted t ensure that the mdeled peratins d nt impact lng standing BC Hydr r US fisheries bjectives. Within the residual flexibility available, each scenari is then assumed t be perated t maximize the dwnstream pwer benefits based n frecasted energy market prices. While the residual flexibility is cnsidered t be available within the mdeling, it is ntewrthy that any agreement signed with the US will likely be structured as an enabling agreement. Thus, the flexibility t perate Nn-Treaty Strage will nt be unilateral by either party, but rather will nly be usable by mutual agreement. In the Base Case High Vlume Utilizatin scenari (Scenari A), it is assumed that BC Hydr wuld nt apply any vlume restrictins n the peratin f Nn-Treaty Strage. This wuld allw fr transactins that culd ptentially draft up t 4.5 MAF frm Nn-Treaty Strage. This scenari is cnsidered t apprximate the peratin that wuld be expected in the 1990 Nn-Treaty Strage Agreement. As well, the level f flexibility and peratinal utcmes are cnsidered t be generally cnsistent with peratinal alternatives that were cntemplated during the Clumbia Water Use Plan. An alternative Lw Vlume Utilizatin scenari (Scenari C) is als cnsidered. Under this scenari, it is assumed that the peratin f Nn-Treaty Strage wuld be limited t an verall vlume f abut 2 MAF f net draft. The limitatin in utilizatin f strage may be achieved either; explicitly thrugh an Agreement with the US that has limitatins in strage accunt vlumes, r; thrugh restrictins in the use f strage that wuld be applied by BC Hydr. 3

4 Nn-Treaty Strage Utilizatin An alternative N Utilizatin scenari (Scenari D) is als cnsidered. Under this scenari, it is assumed that the peratin f Kinbasket and Arrw strage is perated exclusively under Treaty rules, and applicable supplemental agreements. The absence f Nn-Treaty Strage activity wuld be the utcme f nt negtiating an Agreement with the US n the peratin f Mica Nn-Treaty Strage. A furth scenari (Scenari B) has als been develped t examine the impact f a request by the US t cnsider mdificatins t spring and summer peratins f Nn-Treaty Strage under dry water cnditins. Under this scenari, it is assumed that the peratin f Nn- Treaty Strage wuld be limited t an verall vlume f abut 3 MAF f net draft. In additin, the scenari mdels a release f water in the early summer t assist in the utmigratin f salmn in the lwer Clumbia River. This additinal flexibility is mdeled as: Freshet release f 0.5 MAF in June n years that have flws that are less than 72 MAF at The Dalles (lwer 15 percentile f HYSIM years). Return f strage in upcming year, if greater than 92 MAF at Dalles (abve average) Market prices and US plant efficiencies were btained frm data inputs used in HYSIM, and are based n the BC Hydr 2008 Lng Term Acquisitin Plan (LTAP) electricity price frecast 3 HUGH KEENLEYSIDE DAM RELEASE MODELING Treaty peratins mdeled in HYSIM used the 2012 Assured Operating Plan t define the Clumbia River Treaty peratin. Bth the Nn-Treaty Strage transactin, and the Treaty supplemental agreements were incrprated by adjusting the physical release frm Arrw Reservir, thrugh an Excel spreadsheet analysis factring three cmpnents, including: The Clumbia Treaty peratins as defined in the 2012 Assured Operating Plan. Critical envirnmental agreements with the US (i.e., rainbw trut flws, muntain whitefish flws, and LCA Prvisinal Draft). The NTSA scenari While agreements with the United States vary frm year t year, a typical agreement prfile was cnstructed. These agreement prfiles were applied t each year f the 60- year inflw data set, with the recgnitin that the change t river flws and reservir strage may vary under each annual agreement depending n inflws and market cnditins. The resulting mdified release frm Arrw was delivered as an input t HYSIM. 4

5 Nn-Treaty Strage Utilizatin Table 2.1: Nn-Treaty Strage Usage Scenaris: Scenari Descriptin Cnstraints A Base Case High Vlume Utilizatin: This scenari allws fr the peratinal usage f all available Nn-Treaty strage. This scenari wuld apprximate the peratin that wuld be expected in the 1990 Nn-Treaty Strage Agreement. As well, the level f flexibility and peratinal utcme is cnsidered t be generally cnsistent with peratinal alternatives that were cntemplated during the Clumbia Water Use Plan. Enabling agreement with maximum Nn-Treaty draft f 4.5 MAF (full available Nn-Treaty Strage at Mica). B C D Mderate Vlume Utilizatin: This scenari allws fr the peratinal usage f a mderate vlume f Nn-Treaty strage (1.5 MAF less than Scenari A). In additin, the scenari prvides the US with flexibility t release additinal water in summer t manage fisheries bjectives. This additinal flexibility is mdeled as: Freshet release f 0.5 MAF in June in years that have flws that are less than 72 MAF (78% f Nrmal) at The Dalles (lwer 15 percentile f HYSIM years). Return f strage in upcming year, if greater than 92 MAF at Dalles (abve average) Requirement t stre back, prir t next release. Lw Vlume Utilizatin: This scenari allws fr the peratinal usage f a limited vlume f Nn- Treaty strage (2.5 MAF less than Scenari A). This scenari can be achieved by either restricting the size f the Accunt via the Cntract, r limitatins being placed n the accunt draft thrugh the enabling agreement frmat. This level f usage f Nn-Treaty strage, is cnsidered t be the minimum vlume necessary t prvide: - Fall/Winter draft fr Kinbasket, t serve system lad. - Key fisheries/pwer peratins in the spring and summer. - Flexibility t manage Kinbasket reservir peratin in exceptinally high inflw years. N Utilizatin: This scenari reflects an peratin that is driven by the Clumbia River Treaty nly. The scenari can be achieved by either nt signing an agreement with the US n the peratin f Nn-Treaty Strage, r by limiting the draft f accunt t zer, within an enabling agreement. Enabling agreement with either: Nn-Treaty active accunt limited t 3.0 MAF, r BC Hydr cnstraining usage f Nn-Treaty water. US with flexibility t release 0.5 MAF f water in spring/summer, under unusually dry cnditins Enabling agreement with either: Nn-Treaty active accunt limited t 2.0 MAF, r BC Hydr cnstraining usage f Nn-Treaty water. N Nn-Treaty Strage Usage 5

6 4 HYDRO SIMULATION MODEL (HYSIM) Nn-Treaty Strage Utilizatin The BC Hydr prject team used the Hydrelectric Simulatin Mdel (HYSIM) t determine the peratins f the BC Hydr system as a whle, including all reservir levels, reservir utflws and river flws n the Clumbia River. HYSIM is designed t mdel the entire BC Hydr system f electricity generatin. This apprach was needed t capture bth the size and imprtance f the Clumbia and Peace River systems within British Clumbia and the fact that their peratins are crdinated t ptimize pwer generatin. Fr a given lad and resurce prtfli, HYSIM will determine the mst ecnmic dispatch f the generating system, subject t perating cnstraints and bjectives, under a range f streamflw sequences. The HYSIM simulates peratin f BC Hydr s integrated electric generatin system n a mnthly time-step. As such, it is able t prvide end-f-mnth reservir elevatins, mean mnthly flws, mnthly generatin and mean mnthly perating csts. It des nt reflect any variability f these utputs within the mnth (e.g., daily and/r hurly). HYSIM simulatins were based n inflw data sets using the time series between 1940 and 2000 (60 years) with an annual lad and resurces as frecasted fr the year (58,650 GWh/year). Mdeling results reflect a single cntinuus sequence f reservir inflws in which the initial cnditins (e.g., Kinbasket Reservir elevatins) fr each year were carried frward frm the end f the previus year starting in LTAP electricity prices used in this study were based n then-current natural gas price frecasts, with variability that was dependant n water cnditins in the Pacific Nrthwest. Key assumptins used in HYSIM mdeling is prvided in the table belw. Within the cnstraints that are placed n the peratin, the mdel will seek t maximize the ecnmic value f system peratin. It is ntewrthy that BC Hydr will nt always hwever, perate the system t achieve the maximum ecnmic value. Examples f cnditins that wuld ptentially result in adjustments t peratins that deviate frm the ecnmic ptimal include: Fld cntrl events dwnstream f Arrw (in Canada r US) that may result in reductins in releases at Arrw, belw Treaty specified flws. System generatin adjustments t enhance Arrw sft cnstraints r ther system bjectives. System generatin adjustments t manage nn-pwer issues in ther river basins. (eg: mdificatins t peratin f Peace Prjects, t facilitate Peace River winter ice cver frmatin). Discretinary Supplemental Agreements that may be negtiated with the US t enhance pwer and nn-pwer benefits. a. HYSIM: Assumptins and Methdlgy Table 4-1 summarizes the assumptins built int the HYSIM. 6

7 Nn-Treaty Strage Utilizatin Table 4-1: HYSIM Assumptins Frecast lad (58,650 GWh/year) Streamflw sequence is frm Octber 1940 t September 2000 BCH gas and electricity price frecast as used in LTAP 2008 Market prices are based n average mnthly prices fr heavy lad and light lad perids Energy limit is based n the estimated mnthly transmissin availability The market prices are adjusted by water year t reflect the impact due t varying streamflw (at The Dalles) Resurces Existing BC Hydr resurces and Independent Pwer Prducers Includes REV Unit 5, MCA Units 5 and 6. Arrw Lakes Hydr generatin (185 MW) Additinal Independent Pwer Prducers Vancuver Island Generatin (265 MW) Clumbia River Operatins Treaty peratin based n 2012 Assured Operating Plan (AOP) Fld cntrl strage requirements based n 4.08/3.60 MAF fld cntrl split at Kinbasket and Arrw Lakes reservirs BC Hydr and Bnneville Pwer Administratin nn-treaty peratin, varying by water year Nn-pwer peratins based n 1 MAF flw augmentatin strage (if pssible) frm January t February and released in July. Libby Crdinatin Agreement peratin (evergreen agreement with US). Release in Aug/Sep, with return in Octber. Release in December with strage in March. Vlume: 0.25 MAF Nn-pwer peratins based n April thrugh June flw shaping fr trut prtectin Minimum Arrw discharge f 10 kcfs year rund Revelstke minimum flw f 5 kcfs. Meet perating bjectives t the extent pssible thrugh the use f Flex peratin Peace River Water Use Plan Cnstraints Willistn Reservir perating range as per water licence Peace Canyn flws cnstraints 51 kcfs frm January t February fr base case Minimum 30 kcfs in March Minimum 11 kcfs frm April t Nvember Minimum 40 kcfs in December b. HYSIM: BC Hydr Operatins The Peace and mainstem Clumbia river systems accunt fr apprximately 70 per cent f BC Hydr s ttal generating capacity. Their large strage capacity prvides BC Hydr with a significant amunt f perating flexibility t c-rdinate their peratins t meet the varius demands n the system and t take advantage f market pprtunities. Therefre, any cnstraints n either system will reduce this flexibility and may als have an impact n the ther system. The Clumbia River system peratin is mdelled in accrdance with the Clumbia River Treaty cupled with critical nn-pwer peratins, and the anticipated usage f the Nn-Treaty Strage Agreement scenaris cnsidered. The Clumbia River Treaty peratin is cmputed based n the 2012 Assured Operating Plan. Dwnstream fld cntrl requirements are based n the 4.08/3.60 MAF split at Kinbasket and Arrw Lakes reservirs. Critical nn-pwer peratins that are cnsidered t be lng standing envirnmental bligatins by BC Hydr and the US, are included in the peratins. Nn- Treaty Strage Operatins are carried ut t maximize dwnstream pwer benefits, 7

8 Nn-Treaty Strage Utilizatin hwever limitatins in these peratins are set such that they d nt cmprmise the well established nn-pwer bjectives n bth sides f the brder. c. HYSIM: Streamflw Recrd The 60-year streamflw sequence used in the HYSIM mdelling was based n the Octber 1940 t September 2000 histrical streamflw. This perid includes a wide range f streamflw cnditins and is cnsidered t prvide a sufficiently large sample t be representative f future streamflw. Each perating scenari was run cntinuusly ver the 60 years f streamflw data using initial cnditins (at the beginning f Octber 1940) that match the cnditins at the end f the streamflw perid (September 2000). This ensured that the same amunt f water was used in each scenari. Sme interests in the lwer Clumbia River are affected bth by flws ut f Arrw Lakes Reservir and the Ktenay River system. T assess the impact f changing cnstraints n the lwer Clumbia River, the same time perid f flws fr the Ktenay River system were paired with each perating scenari n the Clumbia River. Ktenay River flws were independently mdeled n a daily time-step, using expected peratins frm Duncan and Libby dams. These results were cupled with the mnthly time-step releases frm Arrw, that were generated frm the cmbinatin f Treaty and Nn-Treaty peratins (See Sectin 5). d. HYSIM: Market Mdelling Imprt and exprt market transactins are mdelled based the ptimal system peratin fr the assume electricity market prices, and are limited by estimated mnthly transmissin availability. In the Pacific Nrthwest, electricity prices tend t vary depending n the runff vlumes in the Nrthwest. Therefre, the electricity price frecast is adjusted fr each f the 60-year streamflw cnditins used in the study based n the runff vlumes at The Dalles. The assumed price variatins due t streamflw cnditins ranged frm abut +45 per cent f the mean fr a dry year t -25 per cent f the mean fr a wet year. Due t the flexibility f the hydrelectric system, BC Hydr is able t take advantage f market price variability by shaping the generatin t enable market purchases during lw price perids and sales during higher price perids. Any cnstraints n the system may reduce this flexibility, thereby increasing the cst f perating the system. The price frecast used by HYSIM prvides a single view f the market based n certain assumptins. In real time, there may be much mre vlatility due t a range f different factrs, as the early years f this decade have shwn. This vlatility will tend t increase the value f the perating flexibility. It can als result in significantly mre variability in the releases f certain dams within the Clumbia basin. 8

9 Nn-Treaty Strage Utilizatin 5 Generalized Optimizatin Mdel (GOM) Several envirnmental interests in the mid Clumbia River were affected by fluctuating flws frm Revelstke Dam. Since HYSIM prvides nly mnthly flw averages as utput, a mre refined apprach was needed t explre Nn-Treaty Strage scenaris that impacted these flw releases. The Generalized Optimizatin Mdel (GOM) simulated peratins f Revelstke Dam n a shrter (bi-hurly) time step, which allwed changes t these flw fluctuatins t be studied in greater detail. Electricity prices vary ver the shrt term n a daily and weekly basis. BC Hydr uses its system s flexibility t maximize its hydrelectric revenues in respnse t these fluctuating electricity prices. Facilities n bth the Clumbia River and the Peace River system are used in c-rdinatin t achieve this flexibility. a. GOM: Assumptins and Methdlgy The General Optimizatin Mdel (GOM) was used t capture the way in which the entire BC Hydr system was c-rdinated t maximize revenues ver the shrt term, guided by the mnthly HYSIM results. Table 5-1 summarizes the GOM assumptins. Table 5-1: GOM Assumptins Water Years: uses 10 years f streamflw data frm 1 Octber 1964 t 30 September Perid cnsidered t have a wide variatin f market prices and stream flws. BC Hydr 2008 LTAP, 2016/17 lad year, gas and electricity price frecast fr Alberta and the United States. Estimated hurly market prices and transmissin availability. Interir t Lwer Mainland transmissin cnstraints are nt cnsidered. Current transmissin access limitatins t Alberta and United States markets. The market prices adjusted by water year t reflect the impact due t varying streamflw cnditins at British Clumbia and Pacific Nrthwest. The initial frebay and ending elevatins fr each stream flw year in the GOM study, were set t match thse derived by the HYSIM results fr the crrespnding water years. The mnthly ttal energy prductin frm the G.M. Shrum and the Mica generating plants were restricted t deviate by n mre than a certain percentage frm thse derived by the HYSIM. The average mnthly inflws fr the studies were set t the inflws used in the HYSIM. Within each mnth, daily inflws are assumed t be cnstant fr the Peace River system, while the Clumbia River system used inflws that vary daily. The minimum plant utflws fr the base case were assumed t be: G.M. Shrum 1.5 kcfs Peace Canyn: January 52 kcfs February t March 30 kcfs April t Nvember 10 kcfs December 40 kcfs. Mica 0 kcfs Revelstke 5 kcfs Arrw 10 kcfs Frebay limit: Peace Canyn = 8.58 ft Revelstke = 4.59 ft Nte: Plant unit utages were scheduled primarily in the spring, but als in the fall, fr each unit (20 unit-weeks per year f utage at MCA, 15 unit-weeks per year at REV). The unit utages fr each plant in a river system were c-rdinated s that a unit utage at an upstream plant cincides with a unit utage at the dwnstream plant. 9