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The Understand Energy Learning Hub is a cross-campus effort of the Precourt Institute for Energy.

Electricity Generation

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Fast Facts About
Electricity Generation

Principal Uses for Electricity: Manufacturing, Heating, Cooling, Lighting

Electricity is a high-quality, extremely flexible, efficient energy currency that can be used for delivering all types of energy services, including powering mobile phones and computers, lights, motors, and refrigeration. It is associated with modern economic activity and improved quality of life.

Two-thirds of electricity globally is generated from fossil fuels in thermal power plants, where an average of 55% to 70% of resource energy is lost as waste heat. Electricity generation from cleaner renewable energy sources, particularly wind and solar PV, is rapidly increasing.

Steam-cycle thermal plants like coal and nuclear are baseload (must run continuously because they take a long time to turn on and off), while oil and natural gas turbine plants are peaking (they can come online quickly and fill peaks in demand, but are more expensive to run). Hydro and natural gas combined cycle plants are considered intermediate plants.

For more information about electricity, visit our The Grid: Electricity Transmission, Industry, and Markets and Decarbonization of the Electric Power Sector pages.


Energy Resources Used for Electricity Generation

of primary energy resources are used to generate electricity

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Energy Resources Used for Electricity Generation

of primary energy resources are used to generate electricity

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Average US Thermal Power Plant Efficiency

Natural gas* 44%

Coal 32%

Nuclear 33%

*For combined cycle plants

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  • High-quality energy currency: flexible and relatively efficient for end uses
  • Many resources are electric-only: Hydro, Wind, Solar PV, Nuclear
  • Important for modern quality of life, reduced indoor air pollution, and human health
  • Increase in access worldwide allows for improved education and economic activity
  • Growing demand from economic and population growth
  • Increase in electrification due to demand for decarbonization
  • Distributed generation (e.g., residential rooftop solar panels) can give users more control over reliability, help manage growing demand, increase low-carbon generation, and reduce the need for grid updates


  • Difficult and expensive to store, must match supply and demand in real time
  • Opposition due to land use impacts from transmission and distribution (NIMBY/BANANA*)

*NIMBY - not in my backyard; BANANA - build absolutely nothing anywhere near anything

Climate Impact: High*

High gradient
  • 32% of global greenhouse gas emissions come from electric power
  • 25% of U.S. greenhouse gas emissions come from electric power

Environmental Impact: High*

High gradient
  • Air pollution (SOx, NOx, air toxics, mercury)
  • Water use (cooling)
  • Water contamination (nuclear, ash ponds)
  • Thermal pollution (rivers, lakes, oceans)
  • Solid waste (ash, nuclear)
  • Land use
  • Visual
  • Noise
  • Radioactivity
  • Catastrophic failure
  • Power plant decommissioning (especially nuclear)
  • Habitat encroachment and contamination

*These impacts are dependent on the source of electricity. They are high because electricity is currently generated mainly from fossil fuels. As cleaner resources replace fossil fuels, the impacts are being reduced.

Before You Watch Our Lecture on
Electricity Generation

We assign videos and readings to our Stanford students as pre-work for each lecture to help contextualize the lecture content. We strongly encourage you to review the Essential videos and readings below before watching our lecture on Electricity Generation. Include selections from the Optional and Useful list based on your interests and available time.


Optional and Useful

Our Lecture on
Electricity Generation

This is our Stanford University Understand Energy course lecture on electricity generation. We strongly encourage you to watch the full lecture to understand how electricity is generated and the significant role it plays in the global energy system. For a complete learning experience, we also encourage you to watch / read the Essential videos and readings we assign to our students before watching the lecture.

Diana Gragg

Presented by: Diana Gragg, PhD; Core Lecturer, Civil and Environmental Engineering, Stanford University; Explore Energy Managing Director, Precourt Institute for Energy
Recorded on: April 24, 2023   Duration: 58 minutes

Table of Contents

(Clicking on a timestamp will take you to YouTube.)
00:00 Introduction
3:39 History and Significance
11:34 Supply Side – Electricity Generation
46:40 Simplified Economics
55:32 Environmental Issues
57:02 What Lies Ahead

Lecture slides available upon request.

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Additional Resources About
Electricity Generation

Stanford University

Government and International Organizations