Columbia River Drainage

Transcription

1 Columbia River Spring/Summer Run-Off Conditions and Operations for Legislative Council on River Governance August 21, 2012 Boise, Idaho Rick Pendergrass Manager, Power & Operations Planning Bonneville Power Administration Slide 1 Columbia River Drainage Slide 2 1

2 Up through March 2012 Large weather pattern swings for much of the fall and winter October: Very wet, then very dry November: Very dry early, then very wet December: Very dry (near record in spots) January: Wet February: Dry initially, then wet Only one notable cold snap: mid-january Very wet periods kept getting cancelled out by very dry periods By the end of February, it looked like a very average runoff was falling into place The Dalles volume forecasts dropped through early January, then recovered: December 9: 97.6 MAF January 6: 86.0 MAF February 5: 91.2 MAF March 6: 98.8 MAF Slide 3 Winter operations Headwater projects operate conservatively (no deep drafts) through the winter months. Libby, Hungry Horse, Dworshak all draft below Flood Control to meet minimum flow requirements through the winter. Grand Coulee ends February relatively high at elevation ft. anticipating an April 10, draft to ft. in preparation of spring fish operations. Slide 4 2

3 Then March Hit Precipitation 2-4 times normal Cascades/Coast Range: inches of precipitation Up to 12ft of snow in the Mountains (including the heart of the Columbia Basin) Basin average snowpack increased from 101% to 115% of normal in just 4 weeks The Dalles Volume Runoff April 4: MAF 11.6 MAF jump in one month 19.2 MAF jump in two months Slide 5 March & April Operations Headwater projects all begin increasing discharges in response to rising forecasts. Grand Coulee begins drafting hard in April as water supply volume continues to rise, operational challenges arise around the maximum daily draft rate of 1.5 ft/day and concerns regarding Total Dissolved Gas due to spill Grand Coulee reaches its minimum elevation of ft on April 24 as the Initiation of System Refill is declared by the Army Corps of Engineers. Slide 6 3

4 May Operations Cool, dry May slowed snowmelt and runoff Water Supply volume forecast stabilizes Projects begin typical May refill, but with greater than expected inflows Slide 7 Then June hit April and May precipitation near average Wettest June on record in BC portion of the basin Rainfall 2-5 times normal in the upper 2/3 rd of PNW Castlegar, BC: Wettest month EVER (8.70 shattered previous record set in December 1996 by over an inch) Several June rainfall records broken in BC, northern ID, western MT Meanwhile, mild drought conditions developed in southern Idaho Volume Runoff Forecast at The Dalles stabilized, and then jumped again: May 4: MAF June 4: MAF June 29: MAF Final January-July Volume Runoff: MAF Slide 8 4

5 Flow (kcfs) Elevation (ft) June/July Operations on the Kootenai River (Libby Dam) Kootenai Basins experience near 300% of normal precip. Libby ramps up for sturgeon pulse began May 28 with spill starting on June 4. Natural events quickly overtook operations as Libby transitioned to a flood risk management operation designed to stay below flood stage at Bonner s Ferry (1764 ft) and eventually exceeding flood stage in order to control rate of refill. Peak inflow occurred of 76.1 kcfs occurred on June 7. A deviation request was approved by the Corps in late June to allow Libby to surcharge 2 ft above it s full pool elevation in an effort to maintain a lower release rate thus providing flood stage reduction benefits downstream in both US and Canada. Libby outflows peaked at 48 kcfs July 3-7. Libby s elevation peaked at ft. Bonner s Ferry Flood stage peaked at ft. Kootenay Lake near Nelson BC peaked at an elevation of ft (highest level in 38 yrs.) Slide 9 Libby 80 Avg Outflow Avg Inflow Elevation /1/2012 4/21/2012 5/11/2012 5/31/2012 6/20/2012 7/10/2012 7/30/2012 Date 2370 Slide 10 5

6 Flow (kcfs) Elevation (ft) June/July Operations on the Upper Columbia (Canadian Projects) Early June Arrow operated to maintain trout spawning flows. 1.1 maf stored into Non Treaty Storage space in June (when flows at McNary exceeded 300 kcfs) As June progressed and flows continued to rise, flooding at Birchbank became a major concern. Arrow outflows aimed to maintain a flow at Birchbank (confluence of Columbia and Kootenay Rivers) of no greater than 175 kcfs. In an effort to control refill and manage discharge, all remaining Non Treaty Space space (1.5 maf) was filled by July 13 and Mica, Duncan & Arrow were granted rights to surcharge projects as necessary into Treaty space. A total of 3.5 maf was stored into Canadian reservoirs (in addition to normal refill) by July 13. Arrow discharge peaked at 115 kcfs and Birchbank flows peaked at 215 kcfs. (Absent Treaty Dams, peak flow at Birchbank was estimated to reach 370 kcfs) Slide 11 Arrow 140 Avg Outflow Avg Inflow Elevation /1/2012 4/21/2012 5/11/2012 5/31/2012 6/20/2012 7/10/2012 7/30/2012 Date Slide 12 6

7 The rest of the summer Inflows around the region have dropped sharply. All projects except Libby are targeting BiOP end of August/September elevations. Libby is reducing discharge targeting 12 kcfs by end of August and transitioning to 8 kcfs in September for habitat work Non-Treaty Storage is being released to achieve a maximum rate of discharge of 87 kcfs at Arrow. Slide 13 Natural Runoff Profile Comparison Slide 14 7

8 Oversupply Management Spring 2012 Slide 15 Pacific Northwest Oversupply In order to avoid electric system reliability risks, loads and resources must continuously balance this is the responsibility of the Transmission operation When generation exceeds loads the difference must be exported, reduced, turned off or in a hydro system, spilled Hydro can spill surplus water over dams until Total Dissolved Gas exceed levels set by state waivers per Clean Water Act. Spilling increases gas concentrations Sending water through Turbines Keeps gas levels lower The region has long coped with temporary oversupply events due to large spring run off events. The rapid increase in wind power in the NW in recent years has significantly increased the region s energy generation and at times can compound the oversupply conditions. Slide 16 8

9 Wind Generation Capacity in the BPA Balancing Authority Area Slide 17 BPA Balancing Authority Load & Total Generation Spring 2012 Conditions Slide 18 9

10 Actions to manage Oversupply Last fall/winter BPA and BC Hydro released water from non-treaty storage in Canada. The space created by the releases last fall/winter has allowed outflows from Canadian hydro projects to be lower than they would have been absent the Non-Treaty Storage agreement. BPA and BC Hydro stored nearly 3.5 million acre feet (MAF) under this agreement between May 26 July 15 to be released in August/September when streamflows are lower This amount of storage is roughly equivalent to 44 ft at Grand Coulee Dam or 2800 MW-mo of energy if run through the system BPA acquired over 60,000 MWh in spill exchange with the Mid-Columbia hydro projects. In a spill exchange, one hydro project with short-term spill flexibility elects to spill in order to allow another generator with less spill flexibility to produce more electricity. Sold significant amounts of energy at zero cost Operated units at Grand Coulee inefficiently in light load hours in order to pass additional water through the turbines rather than over the spillway which produces more TDG which can be harmful to fish. Slide 19 Actions to manage Oversupply Implemented additional spill at FCRPS projects within prevailing water quality standards Maximized the amount of irrigation pumping load, especially during light load hours. Reduced Columbia Generating Station to 85% during periods when it was helpful to minimize spill. Deferred non-essential scheduled hydro generation outages and maintenance activities INC/DEC reserves have been occasionally reduced to manage to system operational objectives this Spring. Recallable energy sales were used to increase the ability to generate during hours where demand for electricity is high moving water out of low demand periods and as a result reducing the amount of oversupply spill. BPA displaced approximately 49,700 megawatt-hours of wind with free hydro. Slide 20 10

11 Days of Oversupply Slide 21 Oversupply Management in early July Slide 22 11

12 Oversupply Looking Forward FERC issued a December ruling that BPA s 2011 policy could not be implemented again. BPA filed for clarification & rehearing. BPA filed a FERC tariff revision in March to address Environmental Redispatch. Develop an equitable protocol for managing oversupply operational & cost allocation issues. Multiple parties engaged in settlement talks. BPA believes that one affordable solution to this challenge of too much water and wind power during high spring run-offs is to amend state RPS laws. This could allow wind generators to earn renewable energy credits for the wind power that would have been produced, had we not displaced it in the middle of the night when consumer loads are low. Slide 23 12