Lecture 1.2: Designing Reliable Energy Systems

  • No perfect energy system—only trade-offs
  • Design = balancing reliability, cost, environment, equity

Today's Essential Questions

  • Why do some energy sources fail when others don't?
  • What makes a grid reliable (or not)?
  • How do policies shape who loses power first?

Connecting to Our Last Investigation

  • Hexagon Lab: Power plant → wires → homes (simple…or is it?)
  • 2021 Texas freeze exposed fragility
  • Today: why sources failed, and who was impacted

The Balancing Act: Supply Must Match Demand

  • Supply must equal demand—every second
  • No big “bathtub” to store electricity
  • Flip a switch → plants adjust instantly

Energy Source Reliability: Cold Stress

  • Different sources failed for different reasons
  • Design + preparation matter as much as the fuel

Natural Gas Power Plants

  • Many plants tripped offline (fuel froze/diverted)
  • Pipelines not winterized; gas prioritized to heat homes
  • Lesson: infrastructure prep matters

Wind and Solar: Weather Dependence

  • Wind: icing can halt turbines; cold-weather packages mitigate risk
  • Solar: output drops with clouds/snow; benefits from storage/backups
  • Design must match climate and plan for extremes

Nuclear Plants

  • One reactor offline; others stayed up
  • Cause: specific equipment issue (water pump), not cold itself
  • Lesson: robust but complex systems can still fail

The Storage Challenge

  • Grid-scale storage is hard (and costly)
  • Batteries: minutes–hours, expensive
  • Pumped hydro: needs mountains + water
  • Compressed air: emerging
  • Result: supply ≈ demand in real time

The Human Cost: Who Was Hit Hardest?

  • Older infrastructure failed first
  • Lower-income areas had less investment
  • Mobile home parks: poor insulation → risk faster

Who Kept Power (and Why)?

  • Critical circuits (hospitals, police)
  • Wealthier areas often shared circuits with critical loads
  • Industrial zones prioritized for economic reasons

Equity Question

  • Should reliability depend on ability to pay?
  • Or is reliable power an essential service for all?

Policy Trade-offs: Reliability vs. Cost

  • More reliability = more redundancy = more $$
  • Who pays—and how much to prevent rare disasters?

Policy Trade-offs: Environment vs. Security

  • Renewables: low carbon, weather dependent
  • Fossil fuels: controllable, emit CO2
  • Balance today’s needs with long-term impact

Policy Trade-offs: Local vs. Regional

  • Local plants: jobs + tax base
  • Regional transmission: share resources, higher reliability
  • Which benefit do we prioritize?

Thinking Lens: Cause and Effect

  • Extreme weather → equipment failures
  • → supply shortages → demand spikes
  • → grid instability → blackouts
  • Small failures can cascade into big outages

Preparing for Next Investigations

  • Analyze wire resistance data
  • Evaluate design trade-offs in circuits
  • Apply engineering thinking to community energy needs

Checks for Understanding: Scenario

  • Heat wave: AC demand up; solar panels less efficient
  • Which sources are most/least reliable—and why?

Checks for Understanding: Trade-off

  • A) Local backup generators for essentials
  • B) Regional transmission upgrades
  • Pros/cons for reliability, cost, equity?

Checks for Understanding: Equity

  • Same population, different incomes
  • Who likely faces longer outages—and why?

Summary: Why Do Sources Fail Differently?

  • Different vulnerabilities: weather, fuel supply, complexity
  • Preparation and design drive performance

Summary: What Makes Grids Reliable?

  • Diverse sources + maintained infrastructure
  • Plan for extremes; fast response to match demand
  • Storage limits make timing critical

Summary: How Policy Shapes Outages

  • Investment priorities and regulations
  • Circuit design and emergency protocols
  • Determines who gets protected first

Crosscutting Reflection

  • How did cause-and-effect thinking clarify the crisis?
  • How can systems thinking build more resilient grids?

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