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CHP in the E3 GHG Model Proposed Changes for Stage 2. April 1, 2008. Process Notes. Presentation describes the E3 proposed approach for including CHP in Stage 2 Hoping for consensus on reference case cost, performance, and penetration inputs
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CHP in the E3 GHG ModelProposed Changes for Stage 2 April 1, 2008
Process Notes • Presentation describes the E3 proposed approach for including CHP in Stage 2 • Hoping for consensus on reference case cost, performance, and penetration inputs • Sensitivity analysis can be done by users and inputs can be changed to evaluate alternative cases • All parties will have the opportunity to comment
Agenda • CHP in E3 Stage 1 Model • Key CHP issues • CHP regulatory status under AB32 • Data availability • Thermal/electric split • On-site/grid export split • E3 Proposed Stage 2 model changes • Existing CHP • Adding new CHP • Reference case cost & performance assumptions • EPUC/CAC proposed assumptions
CHP in Stage 1 Model • Stage 1 model contains the CHP units that are in the WECC databases • Stage 1 model does not specify CHP generation as a separate category • Stage 1 model does not have a way to add new CHP generation • Parties requested E3 to add CHP as separate category • E3 requested help from parties in identifying CHP units in the WECC databases
CHP Regulatory Status under AB32 • CARB’s GHG inventory treats CHP as a separate category from non-CHP generation • However, CARB considers part of CHP emissions to be included in CA’s “electricity sector” - i.e. all those that are not associated with “useful thermal output” • Currently, CARB considers emissions associated with “useful thermal output” to be point source emissions, not electricity sector emissions, so separately regulated • CARB reviewing approach to CHP regulation and reporting - status could change
Data Availability • Major data shortcomings for CA CHP • No single source that has capacity, generation, and emissions for all CA CHP • Different capacity size cutoffs for different databases • Little reliable data for small (<1 MW) CHP • WECC databases don’t identify CHP units • Difficult to match EIA Form 920 list to WECC names • Unclear if WECC CHP heat rates are net or gross • E3 model makes assumptions about existing CHP based on best available data
Thermal/Electric Split • Emissions for thermal and electric regulated separately under current scheme • CARB inventory split based on EIA Form 920 (generation & fuel use) and predecessor data • EIA methodology changed ca. 2003, changing the split significantly • CARB emissions % electric 1990-2003: 63% • CARB emissions % electric 2004: 78% • What is a reasonable thermal / electric split?
On-Site/Grid Export Split • EIA and CARB do not distinguish on-site (i.e. behind the meter) from grid export generation • CEC estimates on-site non-PV generation in load forecast, data reliability and overlap with EIA/CARB data uncertain • Plexos does not model on-site generation • What is reasonable assumption for on-site/grid export split for existing CHP fleet?
Proposed Changes in Stage 2 Model • Add CHP as new generation option • Account for CHP generation and emissions separately from non-CHP generation • Provide user controls for cost, performance, and penetration assumptions for user cases • Provide user controls for thermal/electric and on-site/on-grid splits for user cases • Separate treatment of existing and new CHP
Existing CHP in Stage 2 Model • On-site CHP: generation already embedded in load forecast so no adjustment is necessary • On-grid CHP: many CHP units are not identified in WECC database, so CHP fleet generation is underestimated in the Plexos model • This is corrected by adjusting CHP fleet generation and emissions to hit expected values based on historical data • Existing CHP generation and emissions in Plexos summarized, then adjusted in E3 calculator to expected value • Non-CHP generation decremented by the same amount in E3 calculator
CA CHP Capacity by Unit Size Source: EEA database, 2006 data
Existing CHP Expected Values • Units < 5 MW (380 MW, 30% c.f.) generation estimated at 1000 GWh, assumed all on-site • CEC self-gen ~ 11,000 GWh, so ~ 10,000 GWh from units > 5 MW and 1,000 GWh from units < 5 MW • 10-year average EIA total CHP generation and CARB emissions show no trend, so can use for expected CHP • generation: 44,000 GWh • emissions: 30 MMT • electric share of generation and emissions: 63% • Use CHP net heat rate implied in EIA data to be consistent with CARB’s present methodology; however, calculator will track thermal fuel use efficiency proposed by CAC/EPUC
Formulation of Existing CHP Adjustment Col A Col B Col C Col D = A-B Col E= B+D= A Col F= C-D
New CHP in Stage 2 Model • Two categories of new CHP • > 5 MW nameplate = “Large” CHP (cogen) • < 5 MW nameplate = “Small” CHP (self-gen) • Division at 5 MW based on SGIP criteria • Characteristics of large CHP represented by 40 MW gas turbine • Characteristics of small CHP represented by 3 MW gas reciprocating engine
