A Sustainable Planet?

My intention in this essay is to examine the basic facts about the sources of energy available to us, now and in future. And to look at the advantages and disadvantages of each; their potential and their limitations. Any realistic policies that we create are doomed to failure unless they are built within the context of these underlying realities.

There are four sources of energy available to the human race:

1. Solar
2. Nuclear
3. Tidal
4. Geothermal
   

“Haven’t I missed something out?” you may be asking. “What about fossil fuels, wind power, biomass, hydro-electric?”

All of those are less direct forms of solar power. Wind power derives its energy from the movement of air, which in turn is derived from differential heating of the atmosphere in different regions by the Sun.

Hydro-power depends on the falling of water through the gravitational field, but the water that feeds the streams and rivers has fallen as rain, which was evaporated from the oceans – again by the warmth from the radiation of the Sun.

Biomass (eg Firewood, peat, dung, fermentation…) more obviously derives from the Sun, as the source of energy is the capture of sunlight and its storage in energy-rich organic molecules. Directly, in the case of green plants, or indirectly in the case of organisms that feed on the plants (or feed on the ones that fed on the plants… and so on). Similarly muscle-power (whether human or animal)

And finally, of course, fossil fuels are simply stores of biomass energy that was harvested long ago by living organisms over the course of hundreds of millions of years. However the issues relating to these are of course so distinctive that perhaps we should split them into a separate category, before moving on to evaluate each type. So our categories now are:

1. Current Sunlight
2. Ancient Sunlight
   
3. Nuclear
4. Tidal
5. Geothermal
   

In the discussion that follows we shall see that a sustainable lifestyle will be dependent almost exclusively on Current Sunlight as its energy source. No doubt there will be contributions from Tidal and Geothermal schemes, but these are likely to be marginal.

Nuclear fission – the energy released when large unstable atoms such as Uranium and Plutonium are broken up to form a mixture of smaller elements – is simply not an option because of the horrendous cocktail of highly toxic waste products which are produced. These remain lethal for varying periods, and need to be quarantined from contact with any living being for periods of time up to hundreds of thousands of years. Not to mention its intimate (and non-incidental) connection to the nuclear weapons industry.

Nuclear fusion – the energy that powers the sun and the stars, and the explosion of the ‘hydrogen bomb’; energy released when atoms of heavy hydrogen combine to make helium – is not an option either. For one thing because no-one has yet got it to work, but more importantly because even if it did work, it wouldn’t deliver on its core promise of ‘clean energy’. It is true enough that the direct by-product (helium) is not toxic – as are the radioactive isotopes of iodine, caesium, plutonium etc produced in the fission reactors. But the energy extraction process involves bombarding heat-exchangers with high-energy neutrons, thus producing quantities of radioactive scrap.

We are all aware of the downsides of fossil fuel usage in the form of pollution and climate change. But I take the view that these are the least of the challenges – the main one is that we are running out fast – well within Suzannah’s lifetime, out current energy sources will be either exhausted or well on the way.

These are the challenges that face us:

• To develop workable technologies for the harvesting, storage and transport of energy from Current Sunlight
• To get a realistic assessment of the amount of useable energy that can thus be made available
• To design and choose industrial and social structures that can be supported within that energy budget
• To create and implement the strategies that get us from here to there before events overtake us

This essay is no more than an outline – each one of the paragraphs could merit an article of its own – or even an entire book!

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