What LEDs tell us about the future of the world | Stuff Matters

Key Concepts

• Jevons Paradox: An economic theory stating that as technology increases the efficiency with which a resource is used, the total consumption of that resource may increase rather than decrease due to rising demand.
• Light Emitting Diodes (LEDs): Semiconductor light sources that are significantly more energy-efficient than incandescent or fluorescent bulbs.
• Color Rendering Index (CRI): A quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source.
• Learning Curve: The phenomenon where the cost of a technology decreases exponentially as cumulative production and experience increase.
• Matrix LEDs: Advanced automotive lighting technology that uses multiple LEDs to selectively dim or brighten areas of the road to prevent blinding oncoming traffic.

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1. The Historical Evolution of Lighting

Human history is defined by the quest to generate more light for less money.

• Cost Reduction: In the medieval period (1300s–1400s), the inflation-adjusted cost to light a home was approximately £35,000. By the 1900s, with the advent of electric bulbs, this dropped to £260. Today, using LED technology, the cost is roughly £2.
• Societal Impact: This drastic reduction in cost transformed human life, enabling activities like reading after dark, which were previously inaccessible to the masses.

2. The Technological Breakthrough of Blue LEDs

The development of the white LED was hindered for decades by the inability to create a blue LED.

• The Challenge: While red and green LEDs were developed in the mid-20th century, creating the specific crystalline structure required for blue light was an immense technical hurdle.
• The Solution: Three Japanese scientists successfully cracked this problem, earning the 2014 Nobel Prize in Physics. Shuji Nakamura, one of the laureates, is noted for his contribution to this field.
• Efficiency: Unlike incandescent bulbs, which waste the vast majority of energy as heat, LEDs convert the majority of input energy directly into light, significantly reducing carbon emissions.

3. The Jevons Paradox in Modern Application

Ed Conway argues that while LEDs are highly efficient, they may trigger the Jevons Paradox, where efficiency gains lead to increased consumption.

• Automotive Case Study:
  • Halogen Headlights: Consumed ~110 watts.
  • Standard LEDs: Reduced power consumption by ~70%.
  • Matrix/Projection LEDs: While more efficient per unit, these systems use more LEDs to provide advanced features (like adaptive dimming). Consequently, the total power consumption of modern headlights is rising again because we are choosing to use more light and more complex lighting systems.
• Real-World Example: The Sphere in Las Vegas is cited as an example of "new uses" for LEDs—an entire building wrapped in light that would have been impossible to power or maintain with older, less efficient technologies.

4. Economic and Energy Perspectives

• Total Energy Consumption: While individual lighting devices have become more efficient, total global energy consumption for lighting has historically trended upward as we find new ways to utilize light.
• Shift in Power Usage: In the late Victorian era, nearly all available power was dedicated to lighting. Today, lighting accounts for only about 6% of total power consumption, freeing up energy for other technological advancements.
• The Uncertainty: We are currently at a crossroads: will LEDs lead to a permanent reduction in energy demand for lighting, or will human nature—as predicted by William Stanley Jevons—lead us to consume even more energy through increasingly complex and ubiquitous lighting applications?

Synthesis

The transition from fire and candles to LEDs represents one of the most significant efficiency gains in human history. While this technology has democratized light and reduced the energy cost per lumen, it also illustrates the Jevons Paradox. As lighting becomes cheaper and more versatile, we do not necessarily use less energy; instead, we invent new, more intensive ways to use light. The future of energy consumption in this sector depends on whether we prioritize the efficiency gains of LEDs or succumb to the tendency to expand our usage of the technology.