Wind power at the turn of the 20th century
Windmills in the late 1800s were used primarily to pump water on rural homesteads. It was a competitive market, and many innovators worked to improve the technology.
As electrification reached more American homes and farms from the 1930s on, windmills were replaced increasingly with electric motors. Today, concerns about fossil fuels and global climate change are driving new innovations in renewable wind power.
Alternative energy in the 1980s
Knoxville, Tennessee is home to the Tennessee Valley Authority, which supplies electric power to seven states. It also sits in the heart of a major coal-mining region and is about 30 miles east of the Oak Ridge National Laboratory, a leader in energy research. So it is not surprising that the city was selected as the site for the 1982 World’s Fair whose theme was “Energy Turns the World.” From the 266-foot-tall Sunsphere made of energy-efficient glass to the solar panels that powered the US Pavilion and the working windmills at Australia’s exhibition, the fair offered an enthusiastic glimpse into a future fueled by new energy technologies.
Solar power in the late 20th century
Jerome Lemelson (1923–1997) created inventions in many fields, including solar energy. For example, page 121 of his notebook documents ideas he had in the 1960s for producing electricity from sunlight. He described a method to focus the sun’s rays in the oval hollow seen in his sketch. The hollow would be reflective and concentrate the sun's heat. That heat would be converted into electricity by semiconductors or other means.
On pages 124–125. he sketched a method to focus the sun’s rays in depressions in a “metallized plastic, laminate, or aluminum sheet” that would concentrate sunlight. The heat created would then be converted to electricity by semiconductors or other means.
Finally, pages 130–131 of his notebook illustrate ideas he had in the 1960s for producing electricity from sunlight by focusing the sun’s rays with metallized plastic film stretched over a wire frame. An electron tube would convert the concentrated light into electrical power.
Solar-powered consumer products—including wristwatches, radios, and calculators—were available soon after solar cells were invented in the 1950s.
Subhendu Guha was born in Kolkata, India. After completing his PhD in 1968, he investigated properties of semiconductors and became interested in their use to convert sunlight into electricity (photovoltaics). Guha focused his research on amorphous silicon, an element found in sand that can be applied as a thin film to produce a photovoltaic material. In the 1990s, he created a photovoltaic panel that was lightweight, flexible, rugged, durable, and easy to install. He also led the invention of flexible solar roofing shingles. Guha believed that it was important not only to reduce reliance on fossil fuels through solar energy but also to make electricity available for people in developing countries where no electrical grid exists.
Colombian-born inventor Amy Prieto’s research on new, fast-charging, long-lasting, and green rechargeable batteries. She joined the Colorado State University (CSU) chemistry department in 2005 after completing doctoral and post-doctoral work at the University of California, Berkeley and Harvard University. She says that she was attracted to CSU because of the culture of collaboration there, with an openness to sharing resources and knowledge that she believes is crucial to her work.
Prieto founded her company, Prieto Battery, in 2009 to take the battery from research to prototype to commercialization. Still in development, the heart of the battery is a thin slice of copper “foam” that, like a sponge, is full of holes. This 3-dimensional structure increases the amount of surface area and allows lithium ions to move more freely and over shorter distances than in conventional batteries that are assembled in flat layers. Prieto explains that “the ions can go in many different directions, but they don’t have to go very far.”
In addition, Prieto’s solid-state battery contains none of the toxic or flammable liquid components found in traditional batteries. “As part of our mission to deliver a battery that can be used by the masses,” the company asserts, “Prieto is working to develop a process that is cost competitive and friendly to the environment.” This includes water-based manufacturing using citric acid (a common natural preservative) and a standard electroplating process.