Lecture 9 Power Sector Analysis
Gang He
October 24, 2022
Sample analytic questions
- How much solar and wind capacity need to be built?
- How cost delince of renewables and storage will change the capacity and generation mix of the power sector?
- How much new transmission capacity is needed to harvest the benefits of interconnection?
- Does CCS has role to play in the power sector decarbonization?
Power sector’s central role
Overarching strategy
- Electrification
- Decarbonization
Why power sector is special?
- Essential good
- Infrastructure
- Technology/network complexity: balance on real-time
- Supply/Demand inelasticity
- Capital intensive
- Investment takes time
- Capital intensive
U.S. electricity flow
Source: EIA
U.S. transmission grid
Source: ArcGIS
Refresh the basics
- Energy and power
- kW, MW, GW, TW
- Heat rate and efficiency (Carnot, 1st, 2nd)
- Thermodynamics
Load factor and load curves
\(LF=\frac{Energy\ consumed}{Energy\ at\ peak\ demand}=\frac{Average\ power}{Peak\ power\ demand}\)
A low load factor means a “peaky” load shape
Source: Masters (2013)
Supply curve and dispatch
Read more: EIA
Power system modeling family
| Type | Production Cost (Unit Commitment and Dispatch) | Network Reliability (AC Power Flow, Dynamics) | Capacity Expansion |
|---|---|---|---|
| Generator Adequacy | Yes | No | Often |
| Flexibility Requirement | Yes | No | Somewhat |
| Transmission Adequacy | Partially | Yes | Typically No |
| Gen Contingencies | Somewhat | Yes | No |
| Transmission Contingencies | Somewhat | Yes | No |
| Frequency Stability | Somewhat | Yes | No |
| Voltage Stability, Voltage control | No | Yes | No |
| Examples | PROMOD, GE-Maps, PLEXOS, GridView | Positive sequence load flow (PSLF), power system simulator for engineering (PSSE) | NEMS, ReEDS, SWITCH, Grid-path, GenX, PyPSA, Haiku |
Capacity expansion models
- Capacity expansion models simulate generation and transmission capacity investment, given assumptions about future electricity demand, fuel prices, technology cost and performance, and policy and regulation
- What mix of generators should we build to meet load?
- Does a policy affect cost of service regions and competitive regions in different ways?
Strength and limits
- Strength: Examine the impacts of power sector policies (or alternative technology/fuel trajectories) on the generation and capacity mix in the mid-to long-term
- Limits: Many do not have chronological unit commitment (i.e., every hour of the year chronologically); some use aggregate (model) plants for dispatch; transmission and power flow are a stylized representation (transport or DC)
- Example questions: Quantifying the impacts of environmental policies on generation and capacity? What are the cost implications of alternative pathways to a low greenhouse gas emissions future? How will alternative future prices of natural gas impact capacity investment? What is the change in consumption and expenditures? What are the efficiency and distributional effects of various policy designs?
Model comparison
Source: Johnston et al. (2019)
SWITCH Model as an example
Source: Johnston et al. (2019)
Key questions in model selection
- Spatial:
- Geographic: state, regional, national, international
- Cost of service vs. competitive regions
- Geographic: state, regional, national, international
- Temporal: time of day, seasons, annual, decadal
- Time steps: Building new capacity, dispatch
- Time horizon: near (2025), medium(2030), long (2050)
- Generating units: individual plants or model plants, representation of capital costs and other production costs
- T&D: pipeflow, transport, DC powerflow, aggregated
- Representation of renewables: RE technologies, availabilities, accessibility cost, variability
- Link with economy wide model, environmental constraints
Typical output: capacity/generation mix
Source: He et al. (2020)
Typical output: transmission expansions
Read more: PyPSA
Unit committment and network reliability
- Unit Commitment Model: Simulate detailed (hourly to sub-hourly) operation of a given system; Assess resource adequacy and other aspects of reliability of a system; Analyze the impact of changes in the system (e.g., retirement/addition of capacity) on system operation; Assess transmission congestion and locational marginal prices; Describe the daily pattern of emissions
- Network Reliability Model: Detailed simulations of the transmission network including dynamic events that can occur in seconds (and cause big problems); these models aren’t run on a day to day basis –they are only run to examine significant changes to an existing system
Emerging trends
- Smart grid
- Distributed generation
- Renewable penetration
- Efficiency improvement
- Electrifying
- DR/DSM
Summary
- Power sector’s central role in decarbonization
- Capacity expansion model to analyze the optimized investment decisions
- Decisions in the real world is much more complicated
- Emerging trends in the power sector
References
He, Gang, Jiang Lin, Froylan Sifuentes, Xu Liu, Nikit Abhyankar, and Amol Phadke. 2020. “Rapid Cost Decrease of Renewables and Storage Accelerates the Decarbonization of China’s Power System.” Nature Communications 11 (1): 2486. https://doi.org/10.1038/s41467-020-16184-x.
Johnston, Josiah, Rodrigo Henriquez-Auba, Benjamı́n Maluenda, and Matthias Fripp. 2019. “Switch 2.0: A Modern Platform for Planning High-Renewable Power Systems.” SoftwareX 10: 100251. https://doi.org/10.1016/j.softx.2019.100251.
Masters, Gilbert M. 2013. Renewable and Efficient Electric Power Systems. John Wiley & Sons.