3.1 Lesson 3 Introduction

Welcome to Lesson 3!

Welcome to this exploration of world energy consumption. In 2024, humanity used approximately 186,000 terawatt-hours of energy that's enough to power every home, factory, vehicle, and data center on Earth. But where does this energy come from? How has our relationship with energy evolved since the days of wood fires? And what choices will determine whether we meet growing demand while protecting our climate?

In this lesson, we will be learning about the changes in energy supply and demand throughout history. We will be looking at both U.S. energy use and world energy use to understand patterns at multiple scales. While there are lots of numbers in this unit, it is important for us to remember trends and estimates, and not worry about the exact values. Energy data is complex and constantly updated—for example, the most recent energy data is available from the EIA U.S. Energy Facts Explained.

To illustrate this approach: In the latest U.S. data, we see that about 9% of U.S. energy comes from renewable sources. But what's most important to remember isn't the precise percentage—it's the bigger picture: petroleum and natural gas are the primary sources of U.S. energy use, and together those two sources account for nearly 75% of total U.S. energy consumption. That trend—fossil fuel dominance with renewables gradually growing—is the key takeaway.

Lesson 3: Learning Objectives

Upon completing this lesson, you should be able to:

• Analyze historical trends to understand how the Industrial Revolution transformed global energy use
• Compare energy consumption patterns across countries and connect them to GDP, geography, and lifestyle
• Investigate interactive data visualizations to see how fossil fuels still dominate—and how renewables are rising
• Evaluate three potential energy futures from the International Energy Agency and consider what "Net Zero" really means
• Calculate real-world applications like energy doubling time to grasp the scale of future demand

By the end, you'll not only understand the numbers behind global energy you'll be equipped to think critically about the policies, technologies, and personal choices that will power our shared future. Let's begin.