Lecture 12 Policy Analysis Uncertainties, Review and Summary

Gang He

December 1, 2025

Sample analytic questions

  • How do I know if I should trust policy analysis results?
  • What are the methods to address uncertainties?
  • What are the emerging topics to improve modeling analysis?
  • How to interpret modeling results to communicate effectively?
  • Where to use model? How to build your analysis?

Projections went off

IEA underestimates solar and wind

Science models are in a better position

Conditions for model robustness

Models can be accurate when they describe systems that

  • are observable and measurable
  • exhibit constancy of structure over time
  • exhibit constancy across variations in conditions not specified in the model
  • permit the collection of ample data

Social economic structural changes

  • Core data and assumptions, which drive results, are based on historical experiences, which can be off if structural conditions change
  • The exact timing and character of pivotal events and technology changes is unpredictable

Changing landscape of new power generation capacities

Shale gas revolution

Renewable costs

Mission impossible

  • Predict the unpredictable
  • Price the priceless

Better modeling uncertainties

  • Define an endpoint of analysis
  • List all uncertain parameters
  • Specify maximum range of values
  • Specify subjective probability distribution for values within the range
  • Determin and account for correlations
  • Probability distribution of model predictions
  • Derive quantitative uncertainties
  • Obtain additional data and repeat analysis if needed

Incoporating political economy

Examples

  • Risk averse investors
  • Subsidies or taxes
  • Carbon lock-in
  • Unequal costs and benefits of climate polices accrue to different groups
  • Public opinion
  • Confidence in political institutions
  • Trade and investments
  • Competence of goverment

Why a model in the first place

  • Description
  • Explanation
  • Experimentation
  • Providing sources of analogy
  • Communication/Education
  • Providing focal objects or centerpiece for scientific dialogue
  • Thought experiment
  • Projection

Modeling for insights

  • Modeling based on research questions
  • Modeling elements, structure, relations
  • Do not over-interpret
  • Do not misinterpret
  • “All models are wrong, but some are useful”. Avoid useless models.

Focusing on structures and relations

Knowing limitations

  • Known unknowns
  • Unknown unknowns
  • “Garbage in, garbage out”

Interpreting results

  • Results are outcomes of assumptions and models
  • Results does not automatically translate to policies
  • Communicating the limitations and uncertainties

Open source

  • Open model (code)
  • Open data
  • Open results
  • Open validation

In Open we Trust!

Ensure model for society

  • Mind the assumptions
  • Mind the hubris
  • Mind the framing
  • Mind the consequences
  • Mind the unknowns
  • Questions not answers

Summary

  • Know the limitation of models
  • Use model appropriately
  • Interpret/communicate the results effectively
  • Models for social good

Review and summary

What have we talked and learned?

Energy grand challenges: net-zero

A five points “climate haiku”

  1. It’s warming
  2. It’s us
  3. We’re sure
  4. It’s bad
  5. We can fix it

Energy vs power

  • Energy is the ability to do work. Energy is power integrated over time.
  • Basic unit: joule = watt·second
  • Power is the rate at which work is done, or energy is transmitted.
  • Basic unit: watt = jourle/second

We need to know what we are talking about!

Common sources of energy and climate data

Energy:
- IEA (OECD)
- EIA
- UN
- WB
- BP Statistical Review of World Energy

Climate:
- NASA
- NCAR
- EUCCI
- UNEP
- NOAA

Carbon:
- CDIAC (Carbon Dioxide Information Analysis Center)
- EDGAR (emissions database for global atmospheric research system)
- Carbon Budget Project
- Carbon Monitor

Human component is the major driver of warming

Social cost of carbon

  • Marginal cost of carbon
  • Cost included:
    • Net agricultural productivity
    • Human health
    • Property damage
    • Energy system costs
  • Cost not included:
    • Unknown impact: physical, ecological, economic
    • Unknown cost: information

Kaya identify

\(F=P \times \frac{G}{P} \times \frac{E}{G} \times \frac{F}{E}\)

Where:

  • F: global CO2 emissions from human sources
  • P: global population
  • G: world GDP
  • E: global energy consumption

And:

  • G/P: GDP per capita
  • E/G: energy intensity of the GDP
  • F/E: emission intensity of energy

Risks and resilience

Energy systems

Energy project economics

  • NPV, discounting, LCOE, learning rate

  • Project economics is useful for basic cost-benefit analysis

  • Getting the price (discounting) right

  • Understanding technology dynamics will help to model future projections

  • Aware of the limitations

Thermodynamics

  • Thermodynamic efficiency
  • Comparing different technologies
  • Thermodynamics provides physic limits

Brayton cycle vs. Rankine cycle

Brayton Cycle Rankine Cycle
Jet, Gas turbine Steam turbine
Open Open/closed circuits
Working fluid in gaseous phase Working fluid phase change

Defining a Rosenfeld Plant

  • 500 MW
  • c.f.: 70%
  • T&D losss: 7%

Results:

  • 3 TWh/year

  • 3 MtCO2/year

  • NYC electricity use: ~4 TWh/year

P-N Junction

Wind

\(P=\frac{1}{2}\rho \pi r^2 v^3\)

Where,
\(\rho\) = Air Density (\(kg/m^3\))
\(A\) = Swept Area (m2) = \(\pi r^2\)
\(v\) = Wind Speed (m/s)
\(P\) = Power (W)

Nuclear

Nuclear fission


Nuclear fussion

Hydro

Hydropower

Pumped storage hydropower (PSH)


\(E=\rho mg(h_2-h_1)\)

Energy demand

  • Energy demand is shaped by dynamic factors: populations, GDP, technology, regulation, and human behavior
  • Understanding those drivers will help us learn the magnitude and profile of our demand
  • Load forecast integrates all insights to the show

Energy efficiency

  • There are barriers for energy efficiency and inforamtion and standards can help address the energy efficiency gap
  • Human behavior is complicated, and understanding it will help us to design policy
  • Rebound is real but might be overplayed, rebound could be good if improve welfare
  • Sustainable consumption and production within the limit

Energy access and energy justice

  • Electricity/energy access is fundamental to other modern services: education, health, and information
  • Energy access also has gender equity, health cobenefits, and other implications
  • Energy justice is important to achieve just transition
  • An reflection on our approaches to energy justice

Energy, environment, and human health

  • Environmental and health impacts are the externalities of energy systems
  • Energy-air-pollution-human health framework of analysis
  • Energy-water-carbon nexus
  • System impacts show the constraint in systems modeling

Energy transition

  • Diverse factors that drive energy transition
  • Common and differentiated solutions to energy
  • Leverage the advantages
  • Addressing uncertainties: geopolitics, wars, pandemic, and more

Power sector decarbonization

  • 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

Big data and AI

  • AI and big data has transformed how we live, and how can we save the planet
  • AI does not automatic add new insights, but it provides powerful tools to analyze increasingly available big data
  • Learning those new tools and skills becomes necessary to work in the field
  • The potential of using AI/big data to analyze our understanding of energy supply/demand and human behavior is enomorous.

Uncertainies and limitation

  • Know the limitation of models
  • Use model appropriately
  • Interpret/communicate the results effectively
  • Models for social good

References

Craig, Paul P, Ashok Gadgil, and Jonathan G Koomey. 2002. “What Can History Teach Us? A Retrospective Examination of Long-Term Energy Forecasts for the United States.” Annual Review of Energy and the Environment 27 (1): 83–118. https://doi.org/10.1146/annurev.energy.27.122001.083425.
Hausfather, Zeke, Henri F Drake, Tristan Abbott, and Gavin A Schmidt. 2020. “Evaluating the Performance of Past Climate Model Projections.” Geophysical Research Letters 47 (1): e2019GL085378. https://doi.org/10.1029/2019GL085378.
Hodges, James S, James A Dewar, et al. 1992. “Is It You or Your Model Talking?: A Framework for Model Validation.” Rand Santa Monica, CA. https://www.rand.org/pubs/reports/R4114.html.
IEA. 2021. “Net Zero by 2050.” International Energy Agency. https://www.iea.org/reports/net-zero-by-2050.
Kaya, Yoichi, and Keiichi Yokobori, eds. 1997. Environment, Energy, and Economy: Strategies for Sustainable. Tokyo: United Nations Univ. https://archive.unu.edu/unupress/unupbooks/uu17ee/uu17ee00.htm.
Koomey, Jonathan, Hashem Akbari, Carl Blumstein, Marilyn Brown, Richard Brown, Chris Calwell, Sheryl Carter, et al. 2010. “Defining a Standard Metric for Electricity Savings.” Environmental Research Letters 5 (1): 014017. https://iopscience.iop.org/article/10.1088/1748-9326/5/1/014017.
Macknick, Jordan. 2011. “Energy and CO2 Emission Data Uncertainties.” Carbon Management 2 (2): 189–205. https://doi.org/10.4155/cmt.11.10.
Peng, Wei, Gokul Iyer, Matthew Binsted, Jennifer Marlon, Leon Clarke, James A Edmonds, and David G Victor. 2021. “The Surprisingly Inexpensive Cost of State-Driven Emission Control Strategies.” Nature Climate Change 11 (9): 738–45. https://doi.org/10.1038/s41558-021-01128-0.
Peng, Wei, Gokul Iyer, Valentina Bosetti, Vaibhav Chaturvedi, James Edmonds, Allen A Fawcett, Stéphane Hallegatte, David G Victor, Detlef van Vuuren, and John Weyant. 2021. “Climate Policy Models Need to Get Real about People—Here’s How.” Nature Publishing Group. https://doi.org/10.1038/d41586-021-01500-2.
Saltelli, Andrea, Gabriele Bammer, Isabelle Bruno, Erica Charters, Monica Di Fiore, Emmanuel Didier, Wendy Nelson Espeland, et al. 2020. “Five Ways to Ensure That Models Serve Society: A Manifesto.” Nature Publishing Group. https://doi.org/10.1038/d41586-020-01812-9.
Supran, G., S. Rahmstorf, and N. Oreskes. 2023. “Assessing ExxonMobil’s Global Warming Projections.” Science 379 (6628): eabk0063. https://doi.org/10.1126/science.abk0063.