Recognising the imminent fossil fuel crisis, many governments and other agencies are looking at sustainable, renewable sources of energy. What are the choices?

Nuclear fission was claimed to produce energy "too cheap to meter" when originally developed. It now produces 7% of the world's power and up to 90% in some countries (France notably). This technology turned out to be relatively expensive and dangerous. Catastrophic leaks of dangerous radioactive material are always possible (and did happen at Chernobyl). The safety measures to prevent radioactive leaks increase the cost of the reactors. Even more problematic is the radioactive by-product from normal reactor operations. This waste will be dangerous for 100,000 years, and storing it safely for this long would be an incredible challenge. Also, nuclear fission reactors produce atomic bomb material, causing international safety issues. Because of these problems, very few reactors have been built recently. Nevertheless, the present energy crisis is looming so large that the US energy plan includes the development of a new generation of safer nuclear fission reactors and a national dump site for the radioactive by-products. Apart from the very serious radioactivity issues, this option is economical, greenhouse gas free, compact and practical.

Hydro-electricity produces 2% of world power. It is clean and renewable but necessitates a suitable geography and climate. Construction of the dams flood large areas and affect the ecology of the river, which then always becomes a difficult political problem. The lack of suitable sites in most parts of the world limits this application.

Wind, solar, wave, tide, geothermal, biomass. These so-called green energies, together make up less than 1% of world power. Their popularity is rapidly increasing. Wind energy in particular has been progressing to the point of being nearly commercially competitive.  The problem with these energy sources is their very low power density. For example: collecting the sea breeze to a height of 30 meters over the American west coast from Seattle to San Diego can power one big city on a good day. They are also intermittent in nature, so if used extensively, a complicated and expensive energy storage system would be needed to fill in periods of low power availability, like at night for solar power. They are very effective in reducing fossil fuel usage by some percentage. Connecting the wind or solar plants to the grid can somewhat reduce the fuel used by gas power plants. On a windless night, the traditional plant runs at full power. But the need for full power backup by fossil fuelled plants is expensive.

Finally, if used extensively, they may not be completely devoid of environmental issues. Suppose that at a certain location, a sizeable fraction of the west coast sea-breeze is intercepted for power generation. Would that have an effect on the weather pattern in and around that region? Let's cover most of Arizona with solar panels and send the power to the rest of the US. Wouldn't it affect the heat balance of that area with possible repercussions further away?

Therefore these renewable power sources are very good at reducing fossil fuel consumption by some relatively small fraction, however, it would be problematic to use them on a large scale to completely free us of our fossil fuel addiction.

The Hydrogen fuel cycle. Hydrogen fuel has been advertised as being a solution to our energy needs. Hydrogen fuel cells do produce power with zero harmful emissions. However, where does the hydrogen come from? It can be manufactured from water using electricity. In effect, it is like a battery, storing electrical power for later use. But the electricity needs to come from a primary power source. If a fossil-fuelled power plant is that primary source, pollution is released at that point of the cycle. Hydrogen can also be produced directly from fossil fuel. In this case carbon dioxide is also released in the atmosphere. So the hydrogen cycle is ideal for mobile applications but a clean primary power source needs to be found to make the full cycle truly clean.

All the alternatives presently considered for complete replacement of the fossil fuel energy economy are difficult and problematic.

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