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A Way to the Most Abundant Energy

Viable solar energy has been a long-sought-after goal, but with new and affordable technologies, we might soon be able to make the switch
The Dawn of Solar Power Issue Cover



Scientific American

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.

No doubt there is an upfront cost incurred by solar—that of adapting the grid’s infrastructure and operations to handling increasing amounts of intermittent solar energy. When full context is included and net values are compared, however, solar may well be our least expensive option to generate electricity. Most fundamentally, the long-term economic soundness of solar technology resides in the fact that it is a natural energy breeder that can drive a growing economy for the long haul. A solar panel will generate many times the energy required to make it over its life.

Intermittency is perhaps the biggest perceived negative. Passing clouds, weather patterns, nighttime and changing seasons are clearly issues to be dealt with. But they have solutions, and these solutions will not cancel out the overwhelming value of solar. They include intelligent deployment, new forecasting capabilities that will enable effective demand management, energy storage, long-distance interconnection and combination with other renewable resources, such as wind power.

I personally view the challenges of matching demand and the planet’s most abundant resource as an incredible opportunity for technological and economic development. For instance, taking advantage of growing new electric demand sectors, such as electric transportation, will open the door to new ways of thinking and new inventions in load management and electricity pricing.

One country seems to have figured this out and is putting such solutions into action right now. With a solar resource considerably smaller than the U.S. has, Germany plans to produce 80 percent of its electricity by 2050 from renewables, and solar will be a major part of this switchover. Germany already generates 22 percent of its energy from renewables, up from 3 percent in 1990. The U.S. has a much easier task: more sun, more space and a demand for electricity—driven substantially by air conditioning—that is well matched to the solar resource. The U.S. could easily shoot for 100 percent. Many other countries could as well.

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