ML11231A816
| ML11231A816 | |
| Person / Time | |
|---|---|
| Site: | 05200012, 05200013 |
| Issue date: | 12/31/2010 |
| From: | Electric Reliability Council of Texas (ERCOT) |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| References | |
| ASLBP 09-885-08-COL-BD01, RAS 20209, 52-012-COL, 52-013-COL, +reviewedgfw | |
| Download: ML11231A816 (28) | |
Text
Report on Existing and Potential Electric System Constraints and Needs December, 2010 NRC000042 05/09/2011 Nuclear Regulatory Commission Exhibit # - NRC000042-00-BD01 Docket # - 05200012l 05200013 Identified: 08/18/2011 Admitted: Withdrawn:
Rejected: Stricken:
08/18/2011
ERCOT Public 2
2010 Electric System Constraints and Needs This page intentionally left blank.
ERCOT Public 3
2010 Electric System Constraints and Needs TABLE OF CONTENTS
- 1.
Executive Summary..............................................................................................................5
- 2.
Transmission Planning Process...........................................................................................9
- 3.
Load......................................................................................................................................11 3.1 Peak Demand............................................................................................................11 3.2 Non-coincident Peak by County.............................................................................13 3.3 Energy........................................................................................................................14 3.4 Hourly Load...............................................................................................................15
- 4.
Generation............................................................................................................................19 4.1 Historical Generation...............................................................................................23 4.2 Future Generation.....................................................................................................25
- 5.
Reserve Margin...................................................................................................................27
- 6.
Congestion...........................................................................................................................29 6.1 Zonal Congestion and Costs....................................................................................29 6.2 Local Congestion and Costs....................................................................................31
- 7.
Transmission Improvements.............................................................................................33 7.1 Improvement Projects..............................................................................................33 7.2 Improvement Costs...................................................................................................35
- 8.
Area Constraints and Improvements...............................................................................37 8.1 Area Constraints and Improvements - Coast Weather Zone.............................39 8.2 Area Constraints and Improvements - East Weather Zone...............................49 8.3 Area Constraints and Improvements - Far West Weather Zone.......................59 8.4 Area Constraints and Improvements - North Weather Zone............................69 8.5 Area Constraints and Improvements - North Central Weather Zone..............79 8.6 Area Constraints and Improvements - South Central Weather Zone..............89 8.7 Area Constraints and Improvements - Southern Weather Zone......................99 8.8 Area Constraints and Improvements - West Weather Zone............................109
- 9.
Summary of CREZ Report...............................................................................................119
- 10. Long Term System Assessment Summary....................................................................121
- 11. Contacts and Links...........................................................................................................123 11.1 Contacts and Information......................................................................................123 11.2 Internet Links...........................................................................................................123
- 12. Disclaimer..........................................................................................................................125
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ERCOT Public 5
2010 Electric System Constraints and Needs Executive Summary 1.
The annual Electric System Constraints and Needs report is provided by the Electric Reliability Council of Texas, Inc. (ERCOT) to identify and analyze existing and potential constraints in the transmission system that pose reliability concerns or may increase costs to the electric power market and, ultimately, to Texas consumers. This report satis es the annual reporting requirements of Public Utility Regulatory Act (PURA) Section 39.155(b) and Public Utility Commission (PUC) Substantive Rule 25.361(c)(15) and a portion of the requirements of Substantive Rule 25.505(c).
Background
ERCOT prepares this report annually to summarize the continuing efforts to plan a reliable and ef cient transmission system. It provides highlights of completed improvements from 2009 through August 2010 and of planned improvements for 2011 through 2015 as well as an analysis of the impact of these cumulative improvements on future congestion.
As the transmission planning authority for the Region, ERCOT works with its stakeholders to identify the need for new transmission facilities based on engineering analysis of four principal factors:
Operational Results - The results of actual ERCOT operations are analyzed on a continual basis in order to identify areas of recurring congestion and to identify activities that can and should be taken to meet reliability standards while gaining ef ciency from the existing network.
Load Forecasting - Load forecasts developed by ERCOT planning staff using econometric modeling techniques, as well as delivery point forecasts developed by the transmission providers, are used to study projected system needs due to customer load growth.
Generation Interconnections - ERCOT processes requests to interconnect, change, or decommission generation throughout the ERCOT Region. Studies of these requests enable planning staff to analyze and respond to the impact of the resulting changes in power injection into the system.
Transmission and System Studies - ERCOT planning staff, with input from stakeholders through the Regional Planning Group (RPG), evaluates and endorses transmission improvements required to meet the North American Electric Reliability Corporation (NERC) and the ERCOT Regions reliability criteria and to reduce expected congestion based on ERCOTs economic planning criteria.
ERCOT Public 6
2010 Electric System Constraints and Needs Highlights This report presents data and updates for each area of the ERCOT Region, including de ned congestion zones, intra-zonal (local) congestion areas, and weather zones. Congestion costs are signi cantly down from a high of over $375 million in 2008, in part due to a combination of events, including a reduction in fuel costs, revised market rules, and transmission system improvements. In 2010, congestion costs were the lowest they have been since 2002.
Since 2009, ERCOT transmission providers have completed numerous improvement projects affecting approximately 1,933 miles of transmission and about 12,299 MVA of autotransformer capacity, with an estimated capital cost of over $2 billion.
$150
$200
$250
$300
$350
$400 Millions ANNUAL ZONAL CONGESTION COSTS
$0
$50
$100
$150
$200
$250
$300
$350
$400 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Millions ANNUAL ZONAL CONGESTION COSTS Northeast-North North-Houston South-Houston South-North West-North North-West North-South thru Q3
$150
$200
$250
$300
$350
$400
$450 Millions ANNUAL INTRAZONAL (LOCAL) CONGESTION COSTS OOMC OOME Down OOME Up RMR
$0
$50
$100
$150
$200
$250
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$450 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Millions ANNUAL INTRAZONAL (LOCAL) CONGESTION COSTS OOMC OOME Down OOME Up RMR (Jan-Sep)
(Aug-Dec)
Weather Zone Completed Improvement In-Service Voltage Circuit Miles Coast Meadow New Switching Station May-10 345 0.1 Coast Alvin New Switching Station May-10 138 East Tyler Grande New Switching Station and New Autotransformer Apr-09 345/138 East Singleton New Switching Station Apr-09 345 0.5 Far West Big Spring - Chalk - McDonald 69 kV Line Rebuild Apr-09 138 35.2 Far West Stanton East - Big Spring Switch 138 kV Line Rebuild and New Auto May-10 138 21.6 North Bowman - Jacksboro Switch Rebuild Line Jun-10 345 46.7 North Central Parkdale New SVC Installation Jun-09 138 North Central Goldthwaite - Evant Line Rebuild May-10 138 24.0 North Central RD Wells - Hickory New Line May-10 69 1.6 North Central Renner New SVC Installation Jun-10 138 North Central W. Levee - Norwood New Line Jun-10 345 6.5 South Lobo New Switching Station Jun-09 138 South Lobo - San Miguel New Line Mar-10 345 113.8 South Central Sandow Switch - Salty - Thorndale North - Taylor Line Upgrade Apr-09 138 21.9 South Central Taylor - Taylor West - Hutto Switch Line Upgrade Jun-09 138 10.1 South Central Sandow Switch - Elgin Switch Line Rebuild Apr-10 138 21.8 South Central Elgin - Gilleland Creek Line Upgrade May-10 138 12.9 South Central Hutto Switch - Salado Switch New Line Jun-10 345 73.8 South Central Hutto New Switching Station and New Autotransformer Jun-10 345/138 West Abilene South - Putnam Line Upgrade Mar-09 138 35.3 West Yellowjacket New Station and Phase Shifting Transformer Jan-10 138 All Areas Total Lines 2009-2010 345/138/69 1,933 All Areas Total Autotransformers 2009-2010 345/139 12,299 MVA
SUMMARY
OF MAJOR COMPLETED TRANSMISSION IMPROVEMENTS
ERCOT Public 7
2010 Electric System Constraints and Needs The planned projects included in this report are estimated to cost over $9 billion over the next ve years and are expected to improve or add 7,866 circuit miles of transmission lines and 27,026 MVA of autotransformer capacity to the ERCOT system. These totals include that portion of the planned Competitive Renewable Energy Zone (CREZ) additions that are planned to be in service by the end of 2013.
Additionally, this report contains an update of the CREZ process as well as a summary of the 2010 Long-Term System Assessment.
Weather Zone Completed Improvement Voltage In-Service Circuit Miles Coast Zenith Switching Station Addition 345 2011 Coast Garrott - Midtown - Polk Upgrade 138 2011 2.4 Coast Zenith - Fayettteville Double Circuit Line Addition 345 2015 120 East Bell County East - TNP One Double Circuit Line Addition 345 2011 82.6 Far West Faraday Switch Station and Autotransformer Addition 345/138 2014 North Central Renner Static Var Compensators Phase II 138 2011 North Central Hicks Autotransformer and Hicks - Elizabeth Creek Double Circuit Line Addition 345/138 2014 3.8 North Central Jack County Autotransformer Addition 345/138 2015 South Central Gilleland Creek Autotransformer Addition 345/138 2011 South Central Zorn/Clear Springs - Gilleland Creek - Hutto Switch Double Circuit Line Addition 345 2011 165 All Areas Total Lines 345/138/69 2011-2015 7,866 All Areas Total Autotransformers 345/138 2011-2015 27,026 MVA
SUMMARY
OF MAJOR PLANNED TRANSMISSION IMPROVEMENTS
ERCOT Public 8
2010 Electric System Constraints and Needs This page intentionally left blank.
ERCOT Public 9
2010 Electric System Constraints and Needs Transmission Planning Process 2.
The ERCOT transmission planning process integrates requests for transmission service to interconnect new power producers and consumers, as well as supports continued safe and reliable service while accommodating growth for existing customers. In collaboration with transmission providers and other interested stakeholders, ERCOT staff assesses the electric needs of existing and potential transmission system users, on both an individual and collective basis, to determine whether transmission upgrades are required and to respond to the need. All ERCOT recommendations are supported by a series of detailed technical analyses in accordance with industry-accepted performance criteria and practices and the Regional Planning Group (RPG) Charter and Procedures.
For this planning process, ERCOT seeks input from all market participants and stakeholders about options and possible solutions. The ERCOT-led RPG is a forum for market participants, as well as the general public, to provide input. Participants of the RPG have the opportunity to highlight needs and to propose solutions, which ERCOT staff will evaluate as a part of the overall system plan. The RPG also provides participants a way to review and comment on proposed projects that address transmission constraints and other system needs.
By utilizing the RPG forum, ERCOT is committed to being inclusive - to share proposals openly and to listen to a diverse spectrum of interested entities - in the development of transmission improvement proposals. Potential projects to be reviewed by ERCOT and the RPG can be proposed by ERCOT staff, individual transmission providers, other market participants, the Public Utility Commission of Texas (PUC), or the general public. The RPG generally meets monthly, as well as exchanges information via e-mail. Agendas and presentations are available publicly, and project les are posted to a secure web site.
As stated in the RPG Charter and Procedures1, major projects must be endorsed by the ERCOT Board of Directors. Following the RPG review, ERCOT staff will complete an independent review of the projects and make recommendations to the ERCOT Board of Directors for approval. The ERCOT Board will be asked to endorse major projects that have met the following criteria:
ERCOT staff has recommended the proposed transmission project based on its analyses of identi ed constraints, including proposals from transmission providers and any necessary requirements to integrate new generation facilities.
The project has been reviewed and considered through the open RPG process.
ERCOT staff has determined the designated provider of the additions.
Following the Board of Directors review, ERCOT will notify the PUC of all ERCOT Board-endorsed transmission facility additions and their designated providers.
1 The RPG Charter and Procedures document is available at http://www.ercot.com/committees/other/
rpg/
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ERCOT Public 11 2010 Electric System Constraints and Needs Load 3.
Forecasting electrical demand and energy is one of the most signi cant factors in determining the future infrastructure needs of the ERCOT power system. Should the forecast understate the actual load growth, adequate facilities may not be in place in time to reliably serve the load. On the other hand, if the forecast overstates the actual growth, facilities may be built before they are necessary, resulting in inef cient use of resources.
To develop the most reasonable load projections for the system, ERCOT load forecasters consider a wide range of variables such as population, weather, land usage, general business economy, governmental policy, and societal trends in terms of both historical load data and the best predicted future indicators available.
Peak Demand 3.1 The 2011 summer peak demand forecast of 65,206 MW represents a slight decrease from the 2010 actual peak demand of 65,776 MW, which occurred during a period of sustained, above-normal temperatures. The ERCOT system forecast for 2011 as reported in the 2010 Long-Term Hourly Demand and Energy Forecast (LTDEF) is virtually unchanged from the system forecast for 2011 as reported in the 2009 LTDEF. This forecast, as compared to a few years ago, is mainly due to the continuing economic recession as re ected in the economic outlook for the state of Texas.
The key factor driving the peak demands and energy consumption is the overall health of the economy as measured by economic indicators such as the real per capita personal income, gross domestic product (GDP), and various employment measures, including non-farm employment and total employment.
ERCOT Public 12 2010 Electric System Constraints and Needs The gure below shows the historical peak demand from 1990 through 2010 and the forecasted peak demand through 2015. The historical compound growth rate for the last ve years is slightly over 1%. The forecasted annual growth rate between 2011 and 2015, the next ve years, is 1.89% due to a strong economic recovery after 2011 re ected in the economic forecast.
The all-time hourly peak demand for ERCOT of 65,776 MW was recently set this past summer, occurring on August 23, 2010.
The Steady-State Working Group (SSWG) load forecast is developed by the aggregation of the individual load forecasts provided by each transmission and distribution provider submitted to ERCOT in the Annual Load Demand Request (ALDR). This forecast uses the non-coincident peak of each individual transmission and distribution provider. The SSWG load forecast, depicted above, was modi ed to remove the Private Use Network (PUN) load that is also excluded from the ERCOT load forecast. The SSWG forecast is used to determine the reliability needs of the ERCOT transmission system.
35,000 40,000 45,000 50,000 55,000 60,000 65,000 70,000 75,000 80,000 85,000 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 MW PEAK DEMANDS 1990 - 2015 Historical ERCOT Forecast SSWG Forecast
ERCOT Public 13 2010 Electric System Constraints and Needs Non-coincident Peak by County 3.2 The loads by county shown to the right are non-coincident peak demand forecasts provided by the transmission and distribution providers in the 2010 ALDR.
The counties with the greatest peak demands are Harris, Dallas, Tarrant, and Bexar. These four counties comprise roughly 46% of the load within ERCOT.
While ERCOTs overall peak demand forecast calls for almost a 2% annual growth rate, some areas within the state are experiencing growth as high as 6.5% per year. As expected, the greatest growth is around the metropolitan areas. The counties with the greatest expected cumulative load growth are Bexar, Harris, Dallas, and Tarrant. Other areas expected to experience signi cant load growth include the counties along Interstate 35 between San Antonio and Waco, counties near Dallas, Fort Worth and Houston, and the lower Rio Grande Valley.
ERCOT Public 14 2010 Electric System Constraints and Needs Energy 3.3 While the peak demand forecast provides an indication of the size of electrical facilities that should be constructed to serve the expected peak demand, the energy usage forecast assists in determining the usage of these facilities over all hours of the year.
The overall energy forecast growth rate from 2010 to 2015 is 2.0%. The forecasted energy growth rate from the actual energy in 2009 to the forecast for 2010 is 0.7%. The key factor driving the low energy consumption is the outlook of the overall health of the economy as captured by economic indicators such as the real per capita personal income, gross domestic product (GDP),
population, and various employment measures including non-farm employment and total employment.
The gure below shows the historical and forecasted energy consumption.
260,000 280,000 300,000 320,000 340,000 360,000 380,000 GWh Annual Energy Consumption 1990-2015 200,000 220,000 240,000 260,000 280,000 300,000 320,000 340,000 360,000 380,000 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 GWh Annual Energy Consumption 1990-2015
ERCOT Public 15 2010 Electric System Constraints and Needs Hourly Load 3.4 Hourly load is an extremely useful tool for understanding the magnitude of change and the pattern of load being served over a speci c time. The following pages illustrate some of the varying load shapes encountered while operating the grid.
The chart below shows the actual load over the time frame of this report.
45,000 55,000 65,000 75,000 MW HourlyMWLoadJanuary2009throughSeptember2010 2009SummerPeak 2010SummerPeak 20092010WinterPeak 2009 2010 15,000 25,000 35,000 2009MinimumLoad
ERCOT Public 16 2010 Electric System Constraints and Needs The following four charts are close up views around the minimum load and the seasonal peaks.
50,000 60,000 70,000 SystemHourlyLoad 2009SummerPeak July11,2009
Saturday July12,2009
Sunday July13,2009
Monday July14,2009
Tuesday July15,2009
Wednesday 20,000 30,000 40,000 63,534 MW@17:00 70,000 SystemHourlyLoad 2010SummerPeak August21,2010
Saturday August 22,2010
Sunday August 23,2010
Monday August24,2010
Tuesday August25,2010
Wednesday 60,000 50,000 40,000 30,000 65,776 MW@17:00 20,000
ERCOT Public 17 2010 Electric System Constraints and Needs 70,000 SystemHourlyLoad 2009MinimumLoad October16,2010
Friday October17,2009
Saturday October18,2009
Sunday October 19,2009
Monday October20,2009
Tuesday 60,000 50,000 40,000 21,390 MW@05:00 30,000 20,000 70,000 SystemHourlyLoad 2009 2010WinterPeak 55,878 MW@08:00 January6,2010
Wednesday January7,2010
Thursday January8,2010
Friday January9,2010
Saturday January10,2010
Sunday 60,000 50,000 40,000 30,000 20,000
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ERCOT Public 19 2010 Electric System Constraints and Needs Generation 4.
Current installed generation capacity2 in the ERCOT Region is about 80,000 MW, which includes about 3,000 MW of generation that has suspended operations or been mothballed but not retired.
In terms of energy produced within ERCOT in 2009, approximately 42% was fueled by natural gas, followed by coal at 37%, nuclear at 14% and wind at 6%. The map below is an indicator of generating facilities across the Region by fuel type, and the pie chart shows the energy produced by fuel type.
2 For additional information, please see the Capacity, Demand and Reserve report posted at http://
www.ercot.com/news/presentations.
Wind Hydro 0.2%
Other 1.3%
Nuclear 13.6%
Wind 6.2%
Hydro 0.2%
Other 1.3%
Natural Gas 42.1%
Coal 36.6%
Nuclear 13.6%
Wind 6.2%
Hydro 0.2%
Other 1.3%
Natural Gas 42.1%
Coal 36.6%
Nuclear 13.6%
Wind 6.2%
Hydro 0.2%
Other 1.3%
Natural Gas 42.1%
Coal 36.6%
Nuclear 13.6%
Wind 6.2%
Hydro 0.2%
Other 1.3%
2009 Energy Generated by Fuel Type Natural Gas 42.1%
Coal 36.6%
Nuclear 13.6%
Wind 6.2%
Hydro 0.2%
Other 1.3%
2009 Energy Generated by Fuel Type
ERCOT Public 20 2010 Electric System Constraints and Needs It is important to highlight the distinction between installed capacity and available capacity. Power from some fuel types, such as wind and water, may not be available coincident with system need.
In terms of installed capacity within ERCOT, approximately 59% is fueled by natural gas, followed by coal at 22%, wind at 11%, and nuclear at 6%.
The pie chart to the right shows the installed capacity by fuel type.
In terms of available generation, the chart to the left illustrates the proportion of generation available after the wind and hydro sources have been discounted using availability factors of 8.7% and 0%
respectively, giving a more realistic view of expected generation by fuel during system peak load conditions.
Coal,22.1%
Nuclear,6.0%
Other,0.9%
Hydro,0.7%
Wind,11.4%
Coal,22.1%
NaturalGas,
58.8%
Nuclear,6.0%
Other,0.9%
Hydro,0.7%
Wind,11.4%
2010GenerationCapacitybyFuelType Coal,24.9%
Nuclear,
6.8%
Other,1.0%
Wind,1.1%
Coal,24.9%
NaturalGas,
66.2%
Nuclear,
6.8%
Other,1.0%
Wind,1.1%
2010GenerationAvailabilitybyFuelType
ERCOT Public 21 2010 Electric System Constraints and Needs In 2010, most generation capacity additions were coal facilities, although new wind and gas-
red generators have been added. The chart below depicts installed capacity additions by fuel type.
The existing generation capacity by county shown on the map to the right is based on information from the generation companies and includes asynchronous ties to other regions, private network generation, distributed generation that is registered with ERCOT, and all Switchable Resources, which are Resources that can be connected to either the ERCOT Transmission Grid or a grid outside the ERCOT Region.
100,000 MW GENERATION CAPACITY BY FUEL TYPE C
l N
l Total Installed Capacity, MW 80 000 90,000 Coal Nuclear Other Hydro Wind Natural Gas (Operational)
Natural Gas (Mothballed) p y
70,000 80,000 50,000 60,000 40,000 20,000 30,000 10,000 0
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
ERCOT Public 22 2010 Electric System Constraints and Needs The map below illustrates the balance of load and generation within each county in the ERCOT Region for the summer of 2010. A county with more generation than load will export generation to other counties; comparatively, a county with more load than generation will import generation from other counties. Please note this map is for general illustrative purposes only, however it clearly shows that the Dallas/Fort Worth area, the Houston area, and the Austin/Round Rock area are importers and dependent on transmission to serve load.
ERCOT Public 23 2010 Electric System Constraints and Needs Historical Generation 4.1 In 1999, ERCOT had approximately 58,000 MW of installed generation capacity. Much of that generation was concentrated in the metropolitan areas of Houston, Dallas/Fort Worth, San Antonio, and Corpus Christi. The map to the right shows generation within the ERCOT Region as of 1999.
Since 1999, ERCOT capacity has grown by adding new generation sites, expanding existing sites, and upgrading or repowering existing units. The additional generation totals almost 45,000 MW. Much of the new installed generation capacity added in the last few years is from large wind projects built in West Texas.
This signi cant change in the generation portfolio has placed new challenges on the adequacy and the reliability of the existing transmission system. The map to the left shows generation added within the ERCOT Region between 1999 and September 2010.
ERCOT Public 24 2010 Electric System Constraints and Needs Since 1999 a total of 136 units have been decommissioned. The map to the right shows generation within the ERCOT Region that has been decommissioned since of 1999. Decommissioning of older plants near metropolitan areas due to economics or environmental restrictions requires ERCOT to undertake an assessment of system reliability needs and to propose maintaining certain units under Reliability Must-Run (RMR) contracts and any transmission alternatives to these RMR sources.
Many factors, including fuel cost, O&M cost, ef ciency, environmental requirements and revenues, in uence whether a generating unit will remain in service or be decommissioned.
Age, as an indication of the relative ef ciency and maintenance cost of a generating unit, has been used to provide some limited insight into some of the factors that are considered in the decommissioning of units. Currently there is over 15,000 MW of generation within ERCOT that is over 40 years in age. Most of the older capacity is located in and around the larger metropolitan areas of the state. The map to the left shows generation that is over 40 years in age.
ERCOT Public 25 2010 Electric System Constraints and Needs Future Generation 4.2 ERCOT has received interconnection requests for proposed generation having aggregate nameplate capacity over 65,000 MW. Of this capacity, over 60,000 MW is considered public information to some degree and is shown on the map to the right.
The following table shows the interconnection requests for proposed capacity by fuel type, as of October 1, 2010.
- The Other category includes generation fueled by petroleum coke, gasi ed petroleum coke, and batteries.
Fuel Confidential LimitedPublic Public Total GasCC 7,471
3,972
12,043
GasCT 600
247
247
Nuclear 5,900
5,900
Coal 1,740
3,213
4,953
Wind 3,628
29,127
5,953
38,708
Solar 340
699
1,039
Biomass 50
145
195
Other 740
1,300
2,040
Total 4,568
40,074
20,483
65,125
ActiveGenerationInterconnectionRequests ByFuelType(MW)
ERCOT Public 26 2010 Electric System Constraints and Needs The following table shows the requests for new generation in ERCOT between October 2009 and September 2010.
There is much uncertainty associated with many of the proposed interconnections. One reason is that multiple interconnection requests may be submitted representing alternative sites for one proposed facility. For this and other reasons, it is possible that much of this capacity will not be built.
Number MW Number MW Number MW Coal 1
15
1
15
1
660
GasCC 2
645
2
645
3
2,940
GasCT 3
643
2
247
Wind 33
6,204
27
6,488
1
250
Solar 9
460
6
260
Other 2
740
2
740
1
1,300
Total 50
8,707
40
8,395
6
5,150
Projectsmayappearinmorethenonecategory ScreeningStudies
Requested InterconnectionStudies
Requested Interconnection
AgreementsSigned FUEL GenerationInterconnectionRequestActivityin2010
ERCOT Public 27 2010 Electric System Constraints and Needs Reserve Margin 5.
Reserve margin3 is the percentage by which the available generating capacity in a system exceeds the peak demand. The chart below shows the historical and projected (as of December 16, 2010) reserve margins for the ERCOT system from 2000 through 2016, as well as the approved target. Between 1999 and 2004, different methodologies were used to calculate ERCOTs margins, which accounts for some of the wide variation of the margins shown. In 2005, the ERCOT Board of Directors approved a methodology that recognizes a generators contribution to reserve is determined more by availability than by nameplate capacity.
Beginning in 2006, the reserve margins have been calculated using this new methodology, applying a 12.5% target. In 2010, this target was adjusted to 13.75% for years 2011 and beyond by the ERCOT Board of Directors.
3 Reserve margin is calculated by the following formula: ((generation - demand) / demand). The Capacity, Demand and Reserve report re ects these calculations.
15%
20%
25%
30%
35%
40%
45%
RESERVE MARGINS 2000 - 2016 Target Reserve Margin 0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 RESERVE MARGINS 2000 - 2016 Target Reserve Margin
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