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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 model proposed changes for stage 2

CHP in the E3 GHG ModelProposed Changes for Stage 2

April 1, 2008

Process notes
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


  • 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
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
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
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
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
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
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
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
CA CHP Capacity by Unit Size

Source: EEA database, 2006 data

Existing chp expected values
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
Formulation of Existing CHP Adjustment

Col A

Col B

Col C

Col D =


Col E=

B+D= A

Col F=


New chp in stage 2 model
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

E3 proposed 2020 bau reference case assumptions
E3 Proposed2020 BAU Reference Case Assumptions

E3 proposed 2020 aggressive ref case assumptions
E3 Proposed2020 Aggressive Ref Case Assumptions

E3 proposed new chp cost and performance assumptions
E3 ProposedNew CHP Cost and Performance Assumptions

Thank you any questions

Thank YouAny Questions?