Pub. 4 2014 Issue 1

22 AT THE CENTER OF UTAH INDUSTRY T he Earth gets an abundance of light and heat from the Sun every day. To be more precise, the upper atmosphere of the Earth receives 174 petawatts (PW). It’s hard — and maybe even impossible — to grasp enormous numbers, but one PW is 1015 Watts, or one quadrillion Watts. The Gulf Stream transports an estimated heat flux of 1.4PW, and theEarth’s atmosphere and oceans transport an estimated total heat flux from the equator to the poles. Not all that light and heat gets through the atmosphere. TheEarth reflects back about 30 percent of it into space. Clouds, land, and oceans absorb the rest. The light and heat affect theEarth in three specificways: • It drives the water cycle. Warm ocean air evaporates and rises. That creates atmospheric circulation, and sometimes storms, until it reaches a high enough altitude to condense into clouds. • It warms the Earth. The average temperature is 14 degrees C, or 57.2 degrees Fahrenheit. • It is converted by plants into chemical energy. The Sun is an ideal energy source. According to Nature’s chief news and feature editor in 2006, it produces more energy in one hour than the entire world uses. But that doesn’t mean people have figured out how to harness it. Harnessing solar power is going to take some creative thought and effort. The Sun’s energy is free; making use of it is not. As Slate magazine’s Bjørn Lomborg pointed out in an article publishedFebruary 18, 2012, Germany has invested more than $130 billion in solar energy, yet it has only been able to create 0.3 percent of Germany’s energy needs. That doesn’t meanGermany is donewith its experiment. According to a January 18, 2014 article in The Economist, Germany’s lofty goals for renewable energy production require the share of renewable energy from sun, wind and biomass to rise to 80% of electricity production, and 60%of overall energy use, by 2050. German consumers and voters like these targets. But they increasingly dislike their side-effects: namely, the rising cost of electricity. The Economist article points out that at certain times on some days, sun and wind power may provide almost all German electricity. But the sun does not always shine, especially in winter, and the wind is unpredictable. And batteries— storage technologies that, for example, convert power to gas and back again to electricity—on a scale sufficient to supply a city are years away. So conventional power plants have to stay online in order to assure continuous supply. Solar energy can be put to use in twoways – passive and active. Passive techniques have been used for as long as people have been building houses. The ancient Chinese andGreeks used advanced solar architecture and planning methods for their cities. Passive solar design can give people solar lighting, heating, and even ventilation. One design, called Socrates’ Megaron house, is an example of passive solar design that is still influencing solar architectural techniques today. When you think of the amount of energy required to cool homes during a hot summer, the thought of building a passive solar energy home makes even more sense. Passive techniques consist of ideas such as: • Orienting a house to take advantage of the sun; for example, making sure that all the bedrooms face east so they get plenty of morning sunlight. • Using materials with useful thermal properties. A light or white colored roof or road can reflect heat; black ones absorb heat. Both can be helpful. • Spaces can be designed to circulate air naturally. Active techniques involve photovoltaic panels, pumps, and fans that convert sunlight into something useful, like electricity. • Photovoltaic devices. These are solar cells with highly purified silicon that change sunlight into electricity. If you have a solar-powered watch, calculator, or yard light, then you already have some familiarity with these. • Solar thermal power plants generate electricity indirectly. Coal has often been burned to heat water and produce the steam to power turbines and engines. Solar thermal collectors can do the same thing. By heating a fluid, such aswater, oil, or brine, you can create steam. If you are TO WORK PUTTING THE