ScreeningLevel REZ Analysis Tool: Outstanding Modeling Questions

1
Screening-Level REZ Analysis Tool Outstanding
Modeling Questions

• Lawrence Berkeley National Laboratory
• Black Veatch
• Generation Transmission Modeling Work Group

2
Overview of Open Modeling Issues

• Transmission Component
• Distance estimation
• Lumpiness of transmission
• Not lumpy
• Lumpy
• How is cost calculated for underutilized lines?
• What size/ configuration of lines are used in the
  model?
• Inclusion of multiple resources on the same line
• How is cost calculated for complementary
  resources
• Bus-bar costs
• Granularity of resource data
• Market Value Adjustment Factors
• Adjustments to include in model
• Load Zones
• Number and location
• Non-REZ Resources
• Storage

3
Transmission Lumpiness

• Transmission is lumpy, but transmission costs to
  deliver a resource can be modeled with this
  lumpiness excluded or explicitly accounted for in
  the model.
• Options
• Not lumpy transmission costs are assumed to be
  based on pro-rata share of a transmission line
  (i.e. /MW-mile).
• Unit costs and losses can vary depending on
  user-defined line voltages (e.g. 500 kV line
  costs 1,500/ MW-mi and 345 kV line costs
  2,000/MW-mi)
• User can define an assumption such that the
  amount of transfer capacity is less than the
  nameplate capacity of the resource (e.g. 1 MW of
  wind requires 0.7 MW of transfer capacity)
• Lumpy transmission costs are explicitly based on
  a discrete line being built for any new resource
• Sizes of lines to include in model (voltage and
  number of circuits)?
• How to accommodate resources that are smaller
  than transfer capacity of new line?
• How to accommodate multiple resources on the same
  line (explicitly in the model)?
• How to account for improved transmission
  utilization of complementary resources?
• Initial Recommendation
• Requires discussion, TBD.

4
Lumpy Transmission Underutilized Lines

• How to accommodate resources that are smaller
  than transfer capacity of new line?
• Options
• Full cost of transmission line is allocated to
  resource. Transmission utilization is very small
  if resource is small (e.g. FEAST and E3 models)
• Starting point assumption for transmission cost
  is allocated on pro-rata basis (i.e. not lumpy),
  but resources smaller than transmission capacity
  of 500kV are flagged. User can either adjust
  transmission utilization to show underutilized
  line or leave starting point value assuming some
  other resource will be available to use the line
• Initial Recommendation
• Starting point assumption is cost allocated
  pro-rata, but flagged for small resources.

5
Transmission Sizes of Lines

• How many different transmission voltage options
  should be provided? What should be the starting
  point assumption?
• Need to determine transmission costs and losses
  for each option
• If transmission is modeled as lumpy, also need to
  determine transfer capacity of each voltage level
• Options
• Voltage level
• 345 kV AC
• 500 kV ACDC
• 765kV AC
• Circuits
• Single
• Double
• Initial Recommendation
• 500 kV single circuit AC as a starting point
  assumption. The user can select any of the above
  mentioned options.

6
Transmission Multiple Resources

• Should the model have the capacity to model
  multiple resources on a single lines? Should the
  model be able to calculate the improvement in
  transmission utilization due to combining
  complementary resources?
• Options
• Benefits of combining resources are estimated
• Within the model (See next slide how would this
  be done?)
• External to the model
• Not considered
• Initial Recommendation
• If transmission is modeled as lumpy, the model
  should allow the user to select a combination of
  resources to fill up the transmission line
• Additional value of complimentary resources, if
  considered, should be estimated by external
  analysis

7
Transmission Utilization Improvement for Multiple
Resources

• Transmission utilization (TU)
• If the transmission capacity is equivalent to the
  name-plate capacity of resources, then the TU is
  equivalent to the capacity factor of resources on
  the line. The transmission utilization can be
  improved, however, by allowing for a small amount
  of curtailment or combining complementary
  resources on the same line.
• How and where should users estimate the
  improvement in TU due to combining complimentary
  resources and curtailment?
• Options
• Within the model by using detailed hourly data
• The model can account for the benefits through
  user-defined assumptions, but the analysis of
  appropriate assumptions is done external to the
  model
• TU improvement due to complementary resources is
  not considered Transmission Capacity Nameplate
  capacity of resources
• Initial Recommendation
• User defined curtailment treated similar to
  transmission losses
• If included, the analysis needs to be done
  external to the model
• Issue needs to be explored further to evaluate
  whether the benefits are significant enough to be
  considered at a screening level analysis

8
Load Zone Selection

• Geographic Granularity of Load Zones
• How may load zones do we need to capture the
  heterogeneity in load zones but still keep the
  model simple?
• Options
• Major metropolitan areas
• WECC load zones
• States
• Initial Recommendation
• Major metropolitan areas, but restricted to about
  15 to 20 load zones

9
Other Adjustments

• Value of seasonal exchange
• Reliability benefits
• Can a user reduce the transmission capital cost
  estimate of particular lines to account for any
  user-defined reliability benefits?
• Inclusion of non-monetary benefits land use,
  emissions, water use

10
Additional Discussion Slides
11
Discussion Slide Transmission Lumpiness

• Costs (with lumpy transmission) from E3 GHG Model
  for Alberta Wind Resources
• Comparison to similar costs but with simple
  1,000 MW/mile (with 15 CRF) to model non-lumpy
  transmission
• Accounting for lumpiness only makes big
  difference in the model for small resource
  quantities