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Editor’s note: The following is the introduction to a special e-publication called The Dawn of Solar Power (click the link to see a table of contents). Published in August 2013, the collection draws articles from the archives of Scientific American.
We have come a long way in taming the sun’s chaotic energy since 19th century efforts to create a solar motor. Today we can efficiently heat water and buildings and even generate substantial transmittable power all from this abundant light source.
Our ability to make use of this power source has coalesced into two distinct flavors. First, we have finite, localized systems: the solar hot water heaters, passive solar heating and the like, where solar energy must be used or stored at the production site, or else it is lost. Second, we have developed more universal technologies, which generate electricity. These systems include photovoltaics—the direct conversion of sunlight into electricity via semiconductors—and concentrated solar power—the production of electricity via high-temperature steam turbines or thermodynamic engines. All solar technologies have been growing steadily over the past couple of decades, but the progress has been truly remarkable with photovoltaics: more than 1,000-fold since the late 1980s and continuing at a robust pace.
Solar is the most abundant energy resource on planet Earth. Even after accounting for weather variation, the average solar power received by the continents alone peaks at 23 million gigawatts. For comparison, a standard size nuclear power plant is one gigawatt. It dwarfs all the other renewable energy resources combined—including wind, hydropower and geothermal—and one year’s worth of solar would far exceed the reserves of finite energy resources (nuclear and fossil) even when counting unconventional shale and deep-sea oil and methane.
Unfortunately, unlike countries such as even the relatively cloudy Germany, solar as an energy source still goes largely unnoticed in the U.S., where the resource is still viewed as marginal by many in decision-making positions. In particular, there is a widely held perception that:
- The solar resource requires too much space to exploit.
- Solar energy is too expensive.
Intermittency caused by weather, day-night cycles and seasons is a showstopper.
Compared with many other energy sources, solar can require relatively little space to create power. To put this resource in perspective, consider that photovoltaic panels covering less than half of the area occupied by U.S. hydropower plants’ artificial lakes would generate all of the electricity consumed in the U.S. (hydropower accounts for only about 6.5 percent of the nation’s electricity.) Another useful perspective is to consider that with current technology, using about 0.4 percent of the earth’s surface would be sufficient to produce all the energy (transportation, buildings, industry, electricity, and so on) consumed by the entire planet. Considering that urban areas already occupy more space than that and that solar technologies are highly suited for deployment within urban and suburban environments—such as on rooftops—space should not be an issue.
Without proper context, solar energy appears expensive to many, for instance, when comparing it with coal. And too often the conversation stops there. This argument, however, ignores two important phenomena. One is the steady, substantial drop in solar prices, with no end in sight. The second is the net value delivered by solar. It displaces conventionally generated energy, along with the associated direct financial and environmental costs. It does so while providing a good match to peak electrical demand and reducing the risk of demand-driven outages. It also acts as a hedge against energy commodities’ price fluctuations. Additionally, it helps to fuel economic development by creating more jobs per energy unit than conventional generation. Finally, it provides long-term benefits to society in that well-built solar energy systems will last many years beyond their business cycle and will continue to deliver clean energy to society long into the future.