鈥淚t has been a favorite pastime for the dreary gentlemen who juggle with statistics, solemnly to calculate the date on which we shall all freeze to death from exhaustion of the coal supply,鈥� Harper鈥檚 Weekly noted dryly in 1903. It was not a new worry even then, for Britain鈥檚 geologists had been summoned to Parliament as early as 1829 to estimate when the country鈥檚 coalfields would be mined out.
Victorian engineers found solar power an irresistible solution, and one of the most eminent, John Ericsson 鈥� inventor of the screw propeller and the ironclad warship USS Monitor 鈥� devoted the rest of his life to it. 鈥淎 couple of thousand years dropped in the ocean of time will completely exhaust the coalfields of Europe,鈥� he remarked. 鈥淭he application of the solar engine is almost beyond computation, while the source of its power is boundless.鈥� The result? In 1914, his ideas inspired a scheme to run the whole of Europe on solar power, and it might have even worked鈥�
THOUGH fly-by-night solar firms flourished in America in the late 19th century, their products were not entirely fanciful: some irrigation systems and hot water tanks ran on solar motors. But most solar engineers believed the technology鈥檚 future lay in Africa, where French inventor Augustin Mouchot had built desalination plants in Algeria in 1877. His rival, Swedish-American John Ericsson, foresaw a day when energy politics would shift the balance of power towards the deserts of the Middle East: 鈥淭he rapid exhaustion of the European coal-fields will soon cause great changes in reference to international relations, in favor of those countries which are in possession of continuous sun-power. Upper Egypt, for instance鈥︹�� It was a prediction that one inventor took quite literally.
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Frank Shuman started small. In 1906 he built a 鈥渉ot box鈥�, a blackened box under heat-trapping glass. Attached to it, reported Engineering News, was 鈥渁 tiny toy engine such as sold for a dollar鈥�. He quickly moved up to a larger engine and bigger hot box. His third effort, in 1907, took up the whole of his backyard in Tacony, a suburb of Philadelphia. This time, the solar collector was a network of blackened pipes covering an area of 96 square metres and filled with ether, which had a conveniently low boiling point. The heated vapour drove a water pump.
During the summer, neighbours could watch the 2.2-kilowatt contraption pump thousands of barrels of water a day. It even ran during the winter, albeit more slowly. It was certainly safer for neighbours to gawk at than the sun-motors designed by Mouchot and Ericsson. These used costly parabolic mirrors to focus sunlight on a boiler assembly, sometimes producing a temperature of more than 1000 掳C. But Shuman鈥檚 engine was not perfect either. It cooled off so much overnight, and took so long to get going each day that a reporter wondered aloud 鈥渋f it belonged to the Sun union鈥�.
Shuman eventually worked out how to prevent much of the heat loss by floating a thin layer of paraffin upon water in solar collectors to absorb and trap heat. He then lined the bottoms of the collectors with macadam as a watertight insulation that was, he pointed out, 鈥渂lack all through, and therefore will never require painting鈥�. Shuman was particularly concerned with durability and simplicity and felt asphalt would also be 鈥減ractically everlasting鈥�. He also addressed one of the inherent problems of solar energy: how to keep it flowing when the Sun wasn鈥檛 out. Like most other solar engines, his pumped hot water up to an insulated tank, from where it would drive a turbine later.
Shuman鈥檚 designs were only a marginal improvement over those of his rivals, but that didn鈥檛 matter. What Shuman brought to the field was a forceful personality and brilliant sales patter. He made solar power seem inevitable and persuaded investors they would lose out if they weren鈥檛 in at the start of something this big. Soon he was issuing stock for The Sun Power Company, and after an encouraging write-up in Engineering News he won backing from a group of British investors. Along with this financing came two engineering partners, Alfred Ackerman and Charles Boys.
At first they drew up plans to build plants in Florida and Arizona. But Shuman knew there were bigger prizes. In 1912, he and his crew packed their bags and set off for the ultimate destination of any solar engineer: North Africa. Shuman鈥檚 vision took him to Meadi, a farming town about 25 kilometres from Cairo, where the Sun Power team built the largest solar power plant the world had ever seen.
When it was finished in July 1913, the plant had more than 1200 square metres of mirrored V-shaped collectors focused on a blackened pipe. This boiled water to power a 40-kilowatt irrigation system. The Meadi plant ran 24 hours a day, and it was built of simple but strong materials 鈥� Shuman knew that for desert use, simplicity and durability were essential. 鈥淎ny common engineer can run it,鈥� noted Scientific American. 鈥淥wing to the fact that ordinary materials are used in its construction, repairs can be made easily and everything is above ground and readily accessible.鈥�
One visitor to Meadi was Lord Kitchener, the Consul General of Egypt. Impressed with the pumps operating by the ghostly power of the Sun, he offered Shuman a 120-square-kilometre plantation in the Sudan to build his next system. Not to be outdone, the Germans called a special session of the Reichstag to host Shuman. They too wanted solar plants in their African territories, and dangled $200,000 before Shuman to build one.
Shuman was jubilant. Solar power, he boasted, was now inevitable: 鈥淭here is not a single 鈥榮hould give鈥� or 鈥榞uess鈥� about it. Sun power is now a fact, and is no longer in the 鈥榖eautiful possibility鈥� stage. It can compete profitably with coal in the true tropics now.鈥� He had more than irrigation in mind for his future: why not spread the plants across Saharan Africa to generate electricity for all of Europe?
Shuman鈥檚 vision was laid before readers of Scientific American in February 1914: 鈥淚 have taken as a basis the figure of two hundred seventy million horse-power [200 gigawatts] continuously throughout the year being equal to all the coal and oil mined during the year 1909 throughout the world鈥aking the actual work of our plant as a basis, it would only be necessary to cover 20,250 square miles [52,500 square kilometres] of ground in the Sahara Desert with our sun heat absorber unit鈥� Surely from this showing, the human race can see that solar power can take care of them for all time to come.鈥�
Endless power, clean and guaranteed, and financed, Shuman suggested, by spreading the cost with bond issues. That cost would be staggering 鈥� 鈥渘inety-eight odd billion dollars鈥� by Shuman鈥檚 estimate. But, he said, 鈥渢his vast investment would not be made for or by the individual, but for and by the entire human race鈥�. The scale of Shuman鈥檚 vision was daunting but, as he pointed out, the technology was there. All it needed was the will to build it. And Shuman was alert to the political and environmental havoc that petrochemicals might visit upon the world. 鈥淥ne thing I feel sure of,鈥� Shuman insisted, 鈥渁nd that is that the human race must utilise direct Sun power or revert to barbarism.鈥�
Humanity reverted to barbarism sooner than Shuman imagined, and he did not live to see the end of the First World War. Kitchener went down on the ill-fated HMS Hampshire, the Meadi team was assigned to war duties, and all British and German plans for solar power were swept aside. With their post-war economies gutted, and oil in the ascendancy, the notion of spending billions on Sun power was unthinkable. The vision of a solar-powered Europe sank back into darkness.