COLUMN // ENERGY
Photons and Electrons are Intertwined
Lighting has been one of the most impactful applications for new energy technologies for more than 200 years. The electrification of the economy has made that connection even stronger.
Written by Michael E. Webber
To reach mainstream acceptance, new technologies often need the push from a killer app—that one application that makes the pain and expense of adopting new habits and infrastructure worthwhile. Think of the early spreadsheet programs that helped convince businesses to adopt personal computers, or the popularity of highly produced rock albums in the early 1970s in getting audiophiles to purchase high-fidelity FM radios.
For energy, one of the first killer apps was artificial lighting.
For millennia, once the sun went down, the world became a dark and dangerous place, illuminated by candles, oil lamps, or nothing at all. After some experiments in the mid-1700s showed that the gases produced by the decomposition of coal were flammable, entrepreneurs began establishing companies to provide lighting service, supplying a mixture of carbon monoxide and hydrogen that would burn in purpose-built lamps. London launched its public lighting systems in 1807, which used gas lamps to illuminate the city’s dark alleys and streets. Doing so transformed the city, making it safer after sunset and creating a newfangled concept of a “nightlife.”
Gas also showed up in the 1800s for indoor lighting in the houses of rich families. Their gaslights could be operated with a sparker and turnkey valve at the wall.
The gaslight revolution left an indelible mark on the culture. Lamplighters, who would walk from lamppost to lamppost to ignite (or snuff out) the lanterns, appear in books and movies such as Antoine de Saint-Exupéry’s The Little Prince and the 2018 film, Mary Poppins Returns. There is also a theory that the Victorian era’s fascination with ghosts and the supernatural stemmed from mild carbon monoxide poisoning from leaking indoor gaslights.
While the lighting services coal gas provided were highly valued, the danger presented by a network of gas conduits snaking through buildings presented an opening to a newer, cleaner technology.
Enter the electric light.
Though high-brightness electric arc lamps were available starting in the mid-1800s for some public purposes, the rise of the incandescent lightbulb from Thomas Edison’s laboratory in 1878 brought affordable, smokeless, non-combustible light indoors for the homes of a much greater swath of the population. Rather than piping fuel to the customer to burn onsite, Edison’s electric companies provided lighting by burning fuel at a central station to generate electricity and sending electrons over copper wires to the homes and businesses to power lights. The result was a cleaner and more flexible lighting service—and consumers quickly found other uses for the electricity as well.
A London lamplighter testing gas pressure in streetlight in 1910. Photo: Getty
Illumination Evolution
The evolution of using electrons to make photons has not stopped. The electric lighting systems themselves have taken many forms: colorful light emanating from clear glass tubes that sent an electric current through rarefied gases like neon gave Las Vegas, Times Square, and Piccadilly Circus memorable glamor. Fluorescent tube lighting (and its annoying flicker) improved the energy efficiency of office buildings after the energy crises of the 1970s.
The rise of semiconductor light-emitting diodes (LEDs) with discrete wavelengths allowed for point source lighting that could be precisely aimed, which was handy for reading information off CDs, DVDs, or Blu Ray discs. These LEDs lasted much longer (10-20 years instead of 10-20 months) and were much more efficient than fluorescent or incandescent lightbulbs.
Though LEDs were available in a mix of colors, they couldn’t replace white incandescent or fluorescent lighting until the invention of the blue LED in 1983 by Shuji Nakamura, work for which Nakamura received the 2014 Nobel Prize in Physics (and the 2021 Goldstein Energy Lecture Prize from ASME). That invention—and lightbulb efficiency standards established in the 2007 Energy Independence and Security Act—saw LED lights rapidly displace incandescent lightbulbs. (While the widespread adoption of LEDs shows up in national energy consumption data, it also makes itself apparent in the light pollution that washes out night skies.)
Light produced by electrons continues to transform society. Semiconductor lasers use electrons to create well-controlled pulses of photons. Those pulses can travel along optical fibers to carry messages with far greater bandwidth than the microwaves or coaxial copper cables that formed the backbone of the intercontinental communication system in the 20th century. Thanks to fiber-optic networks, the packets of data that are the lifeblood of the internet zip seamlessly from data center to home computers.
Now, however, this electricity-enabled light is causing its own energy crisis.
Rigel reactor cells use light to replace combustion in chemical production. They enable the production of hydrogen and syngas with great efficiency. Photo: Syzygy
Demand for internet data services and especially for services provided by artificial intelligence has led to a boom in data centers and rapidly increased the electric demand from those facilities. According to a December 2024 report by Lawrence Berkeley National Laboratory, the share of U.S. electricity demand directed to data centers could rise from 4.4 percent in 2023 to as much as 12 percent in 2028. Already, some electric utilities are using that projected demand to forgo the retirement of outdated coal power plants.
It’s possible, however, that light could help alleviate data center electricity demand. Solid state physicists have proposed using on-chip optoelectronic devices to facilitate the movement of information within microprocessors, saving energy and time compared with moving energy by conventional hardware such as copper wires.
And while society has been using electricity to make light for almost 150 years, the explosive growth in photovoltaic cells has reversed the flow. Increasingly, we are using light to make electricity or to support the power sector as a whole. For example, we can use lasers to enrich uranium for fission reactors, treat nuclear waste to make it less radioactive, and to initiate fusion.
In fact, light may wind up replacing fossil fuels in many applications. For instance, the chemical industry is a dirty business that burns fuels to produce heat that can be used to fabricate chemicals, releasing emissions on the way. The emerging field of photocatalysis employs bright light to replace heat to drive tightly controlled chemical reactions. Using super-bright LEDs instead of combustion enables the chemical industry to decarbonize, replacing heat with electronically produced photons.
Could photocatalysis be the killer application that ushers in a green chemical industry? That would be a bright idea.
MICHAEL E. WEBBER is the Sid Richardson Chair in Public Affairs, John J. McKetta Centennial Energy Chair in Engineering, and engineering academic director of the KBH Energy Center at the University of Texas at Austin.
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