(This is Part 28 of a series. Go back to Part 27.)
Now that we have looked at alternative fuels that probably are not good contenders, at least not on a major scale, let's look at some alternatives that are potentially more viable:
Wind. Energy from wind turbines is clean, renewable and extremely promising. Of all renewable sources, wind is the one that is being developed the fastest worldwide.
Technologically it is advancing rapidly. Only a decade ago engineers envisioned wind turbines with a maximum output of 300 kilowatts, with optimum wind speeds in a narrow range of only 15 to 25 MPH, and with an energy conversion ratio of less than 20%.
Today wind turbines can be built with three megawatts of power, wind speeds of 7 to 50 MPH—allowing use in a much wider range of conditions—and with much higher energy efficiencies.
Not only that, but leading-edge "wind farms" have been constructed lately that yield electricity in the 3 cents per kilowatt-hour range, competitive with fossil-fuel sources.
However, the U.S. uses 100 quadrillion BTUs of energy annually (100 quads). To supply even a fifth of that by 2030 AD would require the construction of 500,000 wind turbines—20,000 per year. That is five times the present world production capacity of wind turbines.
So even though wind power is very promising, it will not in the next few decades be able to come anywhere near to filling the net energy gap left by declining fossil fuels.
Another challenge concerning wind power is that it is not well suited to meeting the energy needs of the worldwide transportation system. Wind turbines produce electricity, and the question is: How do you store it for use in trucks, autos and planes? With current technology, batteries are just far too heavy and inefficient.
Solar. The most promising area of solar power is solar cells, also known as photovoltaic cells, which convert sunlight directly into electricity. Given the huge amounts of energy falling upon the earth every day, PV power is potentially a vast source of energy indeed.
Like wind power, PV power is clean, renewable and the technology is advancing rapidly. When PV cells were first discovered in the 1950s, the energy conversion ratio was only 4.5%. By 1960 this had reached 15%. Today this figure is 30% and rising.
However, PV energy is expensive. Currently, the most advanced PV installations are producing energy at around 11-15 cents per kilowatt-hour, which is several times what fossil fuels can offer. But as the marginal returns on fossil fuels decline and PV technology advances, it is possible that PV could begin to make a serious dent in worldwide energy needs within a few decades.
In addition, PV technology is ideally suited to providing energy in remote areas in developing countries. It also opens up the possibility of widespread energy production "off the grid", that is, energy production that is small and local rather than centralized in large power plants.
But as with wind energy, solar energy is not currently well suited to providing energy for the vast transportation infrastructure. What is needed is a technology that can "store" the energy created by renewables and release it in an efficient way. And that's where hydrogen comes in.
(This is the end of Part 28. Go to Part 29.)
—jim sloman, 10.23.04 for Jan 13
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