The Myth of Renewable Energy

The continuing demands of certain groups and individuals that society must use more solar energy shows a remarkable shallowness of thought coupled with a terrible lack of foresight. In some respects it may even lead those groups of people becoming a backwater. In a worst case scenario using renewable energy will lead to more global warming that not using renewable energy.

This report does not for a minute suggest that solar energy should be the sole source of energy. What it does do is show that it cannot supply the world's energy needs. This contrasts with the great number of 'greenies' who state quite categorically that there is enough energy falling on the Earth in one day to provide all of our energy needs but apparently without considering the environmental impact of their claims let alone the engineering problems.

It is also clear from the current debate that there is a vast lack of understanding of the problems associated with solar and other forms of renewable energy.
 
Starting from first principles, the solar constant, the energy the Earth receives from the Sun, the figure we all live by, is 8.37 joules (2 small calories) per square centimeter at the nominal distance of the Earth from the Sun. Due to atmospheric absorption the amount reaching the ground at normal incidence, that is, when the Sun is directly overhead, is only 5.86 joules (1.4 small calories) per square centimeter. This figure is available in almost every high school science book.
 
The Sun, however, isn't directly overhead at all times. It rises and sets. It move higher and lower as the seasons pass. It is obscured by clouds much of the time. And it is 'behind' the Earth for fully half the day (on average).
 
Leaving aside polar areas and other areas at high latitudes, the average amount of solar energy per square metre received in areas where solar collectors might be used is nominally 5 kilowatt-hours per day per square metre, instead of the more grandly claimed/assumed figure of 24 kw-hrs, or worse, 35 kw-hrs, per square metre per day over the whole of the Earth, figures that the less well informed, and occasionally even the well informed, tend to throw into the debate on this subject.
 
On top of this, most of the solar energy the Earth receives is already allocated to other uses. For example, we cannot put solar collectors over the wheat paddocks, or over the beaches, or over the forests, or over the cities. One cannot simply claim the planet Earth receives all that energy and we should be using it. It's already being used.
 
Having said that, how much energy does the average person use? How many people check their electricity account, or gas account, to see how much energy they use?

Average domestic energy consumption per person in Western Australia is 10 kw-hrs (A) per day. In Perth, WA, energy usage over the last 5 years has climbed to 20 kw-hrs per day due principally to the increasing use of air conditioners.
 
There is now enough information in the first instance to calculate how much area must be covered by photovoltaic (PV) devices to satisfy Australia's, or the world's, domestic energy needs.
 
It would appear at first glance that each person requires a minimum of 2 square metres of solar collectors.

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Contact:  georgebl@iprimus.com.au