Sunday, October 24, 2010

The Future of Energy: Solar Power Is Coming

The amount of energy the earth receives from the sun each year is more than 10,000 times the total energy needs of all humans on earth. We cannot effectively harness even such a paltry fraction of the sun’s energy yet. In 2008, less than 0.02% of the global energy supply came from solar energy. In most parts of the world, solar energy is simply too expensive. Carbon-based energy such as oil and coal still provide a cheaper alternative, even while harming our environment. Solar energy currently costs about 38 cents per kilowatt-hour, compared with only 5 cents per kWh for oil and less than 1 cent per kWh for coal. Government taxes and subsidies typically reduce this cost disparity slightly, but not enough to make solar energy viable for most people.

Fortunately, this will soon change. Photovoltaic solar cells are typically made of silicon: the same material in computer chips. Engineers cannot shrink the solar panels in the same way that they can shrink transistors, because solar panels need to have a large surface area to absorb as much sunlight as possible. However, they can make the panels themselves more efficient and shrink the thickness of the panels. As a result, solar energy appears to be on a Moore’s Law-like trajectory of its own. Approximately every 18 months, the total solar capacity doubles and the cost falls by 20%. Up until now, this hasn’t been noticeable because it is such a small portion of our overall energy supply. Doubling a small number is still a small number.

However, if this trend continues, solar energy will be able to supply virtually 100% of the earth’s energy needs by 2035. Some observers are even more optimistic, predicting that solar energy will cost about the same as carbon-based energy by 2015. They theorize that after 2015, the capacity of solar energy could increase much more quickly, as consumer demand for solar energy makes it very lucrative and the industry explodes. Other observers are more skeptical; some question whether solar energy is really on Moore’s Law-like pattern of exponential growth at all, suggesting that this recent trend could be caused by other factors.

I think it’s quite clear that solar power will continue to grow at an exponential rate, since manufacturing solar panels requires many of the same techniques that drive the reduction in cost of computer chips. But I wouldn’t count on the industry suddenly exploding in popularity as soon as solar energy becomes slightly cheaper than oil and coal. It’s important to remember that solar energy is not a commodity like oil that can be traded globally. The costs will be much lower in deserts and other sunny areas. By the end of this decade, we may see the American Southwest and Southern Europe starting to switch to solar power, while other regions lag behind, using oil and coal for much longer.

Moving away from fossil fuels will be the single most important step we can take to stop making climate change worse (although much of the damage will already be done, and will continue to accumulate for decades after the switch). An international economy that was not reliant on oil would be much more stable for global security. Many of the biggest potential threats to international stability come from oil-rich regimes, where money from oil exports often funds extremist groups or large militaries that destabilize the region. Furthermore, solar energy prices would be much more predictable than oil. Unlike oil, there would be no maximum amount of energy available; new solar panels could always be added and older panels could be improved, ensuring that the price continued to drop. They would drop at a roughly consistent rate, rather than fluctuating wildly from one year to the next as oil does. Eventually, the energy cost in nearly all products will be virtually eliminated, as solar energy becomes cheaper and cheaper.

Most people look back over recent history and find it difficult to imagine that energy prices will ever go down - just look at gas prices today compared to a decade ago! But in reality, the past decade is an exception, caused by the rapid development of China and India just as we reached peak oil production. In the long term, the broad trend has been for energy costs to decline. Solar energy will ensure that that trend continues for decades to come.

By 2025 – In the United States, solar energy is cheaper than oil on average, on a per kilowatt-hour basis.
By 2035 – The global oil trade is less than 25% the size that it is in 2010 (approximately $2.1 trillion), adjusted for inflation.

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