To foster greater understanding of how we harness sunlight, we will celebrate the UN’s coming International Year of Light by culling from John Perlin’s Let It Shine: The 6000-Year Story of Solar Energy. Perlin’s work is the only book that has thoroughly chronicled the development and application of solar throughout, focusing on key themes, people and events that have laid the foundation for an enduring Solar Age.
I will start this engaging study describing the Year of Light, as envisioned by the UN, followed with an introductory Q&A with Mr. Perlin.
The International Year of Light
On 20 December 2013, the UN General Assembly proclaimed 2015 as the International Year of Light and Light-based Technologies. This International Year will bring together many different scientific societies and unions, educational institutions, technology platforms, non-profit organizations, and private sector partners.
Focusing on the topic of light science and its applications, the UN cited the importance of raising global awareness about how light-based technologies can promote sustainable development in energy, education, agriculture, and health. “Light plays a vital role in our daily lives and is an imperative cross-cutting discipline of science in the 21st century. It has revolutionized medicine, opened up international communication via the Internet, and continues to be central to linking cultural, economic and political aspects of the global society,” writes the International Year of Light website.
As such, the International Year of Light will consist of coordinated activities on national, regional, and international levels. One of the main goals of the International Year of Light will be to allow people of all ages and all backgrounds to gain an appreciation for the central role sunlight has played over the millennia in making life better for humanity through architecture and urban planning; agriculture and horticulture; desalination; solar thermal – water heating, drying, and cooking; and the generation of electricity.
Questions for John Perlin
Meyers: You are slated to be the keynote speaker at COSEIA [Colorado Solar Energy Industries Association] on February 25. What solar issues will you address?
Perlin: My presentation will be based on material from my book, Let It Shine: The 6000-Year Story of Solar Energy. It will show the five major breakthroughs in solar energy as they have evolved over the last 6000 years: learning where the sun is throughout the year; using that knowledge to design houses to stay warm in winter and cool in summer; trapping solar heat with transparent materials for heating buildings, as well as for horticulture, heating water and desalination; using optics for concentrating the sun’s energy to reach temperatures capable of lighting fires; and the discovery of materials that directly convert sunlight into electricity. The lecture will show that rather than being a twentieth century phenomenon, as so many believe it to be, the use of solar energy is the second oldest energy source after firewood. Attendees will discover that houses have been designed since Neolithic times to scoop up sunlight in winter; that over the last three thousand years people have used solar concentrators to focus sunlight to light fires, during the Renaissance, to solder metal, and by the nineteenth century, to run steam engines; that since the end of the nineteenth century a solar water heater industry has developed and spread throughout the world; and that as far back as the 1870s, scientists and technologists have discovered and used certain solid state materials to convert sunlight directly into electricity. The myriad ways people have benefited from solar energy over the last six thousand years proves we can have a wonderful solar future. If thousands of years ago the Chinese, Greeks, and Romans could successfully harness the sun’s energy, can’t we, with a far superior tool kit, do better, using their work as our foundation?
Meyers: As we celebrate the Year of Light, are world citizens correct in saying we are in the midst of a Solar Age? Please elaborate.
Perlin: As Let It Shine shows different regions of the world have been in the midst of a Solar Age at one time or another over the millennia. Solar, for example, has flourished in different forms in China over the last 6000 years. All ancient Greek builders, whether working in the countryside or in urban settings, solely built passive solar for at least three centuries. Currently, almost all Cypriotes and Israelis heat their water with the sun, as did many in southern California more than a hundred years ago. Today we are at the dawn of a new solar age with the combined power capacity of solar water heaters and photovoltaics at almost 400 gigawatts and solar businesses valued at over $200 billion.
Meyers: You begin this series by writing about Socrates, an early champion of building with the Sun. Why?
Perlin: Socrates was one of the founders of Western philosophy. Aristotle was also an early champion of building with the Sun. His writings constitute the first comprehensive system of Western philosophy. Their advocacy of solar architecture therefore places building with the sun in mind squarely in line with western thought. An upcoming article will show Confucius’ interest in solar concentrators, demonstrating that solar was an important topic early on in Western and Eastern thought among the best and the brightest in both cultures.
Here Perlin presents a transcript of Socrates presenting what we would call today a workshop on the strategy and value of solar passive architecture.
Socrates Talks Solar
Xenophon, a student of Socrates, transcribed a talk Socrates gave regarding solar passive architecture. The great philosopher based his interest in building with the sun in mind on the premise that “everything is good and beautiful when well adapted for the end in view, bad and ugly when ill adapted for the same.”
“And so when he spoke about houses,” Xenophon wrote, “and argued that ‘the same house must be at once beautiful and useful’—I could not help feeling that he was giving a good lesson on the problem: how a house should be built. He then pursued the matter by asking, ‘Do you admit that any one proposing to build a house properly will plan to make it at once as pleasant and as useful to live in as possible?’ and that point being admitted, the next question was : ‘Is it not pleasant to have one’s house cool in summer and warm in winter?’ and this proposition also having obtained assent, “Now, a house having a southern aspect, sunshine during winter will enter the interior through the portico [covered porch], while in summer, when the sun is directly overhead, the roof will afford an agreeable shade, will it not? To put it succinctly, in such a house the owner finds a most comfortable retreat year round, making it at once both useful and beautiful.’”
Where did Socrates get these ideas? Archaeology shows that not far from where Socrates lived the first solar retrofits occurred, changing the orientation so all the main rooms faced south. Solar architecture had become so common in his time, that the great playwright Aeschylus could write that a south-facing orientation differentiated the Greek house of his day from the habitations of the primitives of the period, who, “Though they had eyes to see, they saw to no avail; they had ears, but understood not. But like shapes in dreams, throughout their time, without purpose they wrought all things in confusion. They lacked knowledge of house turned to the sun, dwelling beneath the ground like swarming ants in sunless caves.
Coming next: The Five Major Breakthroughs in Solar Energy
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