CNN’S SOLAR SUMMARY

It's such an appealing idea -- all the free energy we need, right up there in the sky. But it's not quite that simple -- yet. Worth working toward, nevertheless.

All About: Solar Energy
Rachel Oliver, October 1, 2007 (CNN)

WHO
The sun

There is a lot of room for solar energy development. (click to enlarge)

WHAT
Solar energy has enormous potential but has yet to overcome several longstanding barriers.

WHEN
2007: solar, wind and geothermal combined only account for around 1% of world electricity (BP Statistical Review of World Energy 2007) and solar is 0.039% of world electricity (International Energy Agency (IEA)).

WHERE
- The sun is at the center of this solar system, a star in a vast galaxy of possibility and darkness.
- The US gets 0.01% of its electricity from solar and Germany produces 50% of current world solar energy but that makes up less than 7% of Germany’s electricity.

WHY
- Greenpeace says the sun can provide 10,000 times the world’s daily need for electricity.
- The Union of Concerned scientists says 20 days of sun matches all the world’s coal, oil and natural gas supplies.
- Problem 1: Intermittency. What do you do when the sun doesn’t shine? Much work is being done with storage. Batteries and other methods of converting solar electricity into something storeable.
- Problem 2: Space. US electricity would require photovoltaic cells over 150,000 square kilometers. (But the US is 3.7 million square miles.) A Rockefeller University report said a hectare of solar cells = 1 liter of nuclear core reactor fuel. (But the hectare doesn’t generate any radioactive waste.)
- 4% of the world’s deserts covered with solar cells could meet the world’s electricity needs – but might represent a too-tempting terrorist target. And making/installing that many solar cells would require a massive infrastructure (like tearing the tops off mountains to get at the coal?)
- Growth so far has been constrained by required materials (silicon, plastic) and infrastructure (plants, installation sites).
- Home installations are limited by costs homeowners are unwilling to take on, even with government incentives and rebates. (China exports 90% of its solar cell production b/c its people cannot afford to install them.)

Concentrating systems using parabolic mirrors for heating liquids piped through to drive steam generators may make it possible to store and transmit solar energy. (click to enlarge)

QUOTES
- United Nations Environment Report: “…an area of 640,000 square kilometers [in the Sahara Desert] could provide the world with all of its electricity needs (the Sahara is more than 9 million square kilometers in size).”
- Friends of the Earth: “…the solar Photovoltaic industry is now the fastest growing renewable energy technology on earth, showing a market growth of 60 percent between the years 2000-2004.”
- The World Bank: “…the global market for solar electricity will be worth $4 trillion in 30 years.”
- Greenpeace/European Photovoltaic Industry Association: “…solar power will be able to power 2 billion people's lives by 2030.”