The relation between the use of fossil fuels and global warming is becoming apparent to most people.   Estimates of the timescale and seriousness of this problem are discussed.   Replacing fossil fuel based power with photovoltaic generation is considered a solution.   Estimates of the potential, economic cost and likely timescale of such a solution are given.

Energy limitations to the global population.

    Most of the world's energy is produced from fossil fuels.   The rate at which carbon dioxide is being added to the atmosphere is likely to double the carbon dioxide content within the next century.   This is the most benign estimate.. A Global warming of between 2 and 6 °C is predicted for a such an increase.   This is thought likely to cause an even larger temperature increase in latitudes away from the equator.
Such a rise in temperature is likely to be accompanied by more serious chaotic changes in the ecosystem -  rises in sea level, destruction of coastal habitats, desertification of the savanna, extinction of plant and animal species, and of much that man depends on for survival.
We have reached a critical point.   Our reliance on carbon combustion is limited, not by the availability of coal or oil reserves but by the atmosphere’s ability to cope with the exhaust gases.

Carbon above our head.

The increasing Carbon Dioxide level

    For every person on this planet, there are 130 metric tons of carbon (mainly in the form of carbon dioxide) in the atmosphere.   At the moment, the average person's energy usage (transport, and industrial production, as well as the direct consumption of electricity) amounts to some 1.2 kilowatts.   Most of this is produced by the combustion of carbon based fuels, and contributes 1.1 metric tons to the atmospheric carbon every year.
Methane, another carbon greenhouse gas, has been shown to be significantly less important than carbon dioxide.
With just the current CO2 production and no significant increase in carbon absorbing vegetation  -  we can see a doubling in about 100 years.
Some climatologists would argue that increase in the phitoplankton of the worlds oceans will provide the necessary sink. However, evidence from continuous records of the atmospheric CO2 at Mauna Loa, Hawaii in the Pacific show:

1). At the current rate of increase, a concentration of twice the pre-industrial revolution level (from 280ppmv to 560ppmv) will be reached in 100 years.
2). The rate of increase is indeed accelerating, and is consistent with a doubling every twenty five years.

Also, the historical record of world carbon dioxide output shows it clearly doubling every twenty five years. With increasing population and spreading technology, the worlds energy consumption will increase rapidly. The world as a whole is likely to  reach the UK’s per capita energy consumption within fifty years.    If the whole world now consumed energy at the rate that we do in the UK, we would see climatic catastrophe in twenty five years - even less with the consumption rate of the USA.   The climatic change has only been held restrained up till now by the low energy consumption of the underdeveloped nations.
Currently, the average energy consumption per person on this planet is 1.2 kilowatts.   This includes heating, lighting, and transport, as well as electric power (its fraction accounting for three times its electrical power value in fossil fuel burning).
We can’t go safely beyond this level without using renewable energy.   The richest viable, safe, non-polluting alternative is solar power, much of which will need to be in the form of electric power.   With 1% of the land surface covered with photovoltaic cells of current efficiency of 17% we could gather 6 kilowatts per person on this planet.

The future solution?
Solar cell design is improving, new materials which would be cheaper to manufacture are being discovered.   Production has increased and prices have reduced.   We have already passed the point where the energy generated by a solar panel, even in the latitude of the UK, will generate enough electricity in its lifetime to pay for its manufacturing cost.   It has been estimated that even in the UK, we could meet all our energy needs merely by cladding all our buildings with photovoltaic cells.
Unfortunately, there is very little financial investment in photovoltaic production or integration into architecture.   The worldwide investment in PV production plants is only of the order of  £250 million.   This produces 250 megawatts of peak generating capacity per year.   In fifty years we need to reach a target of  25,000 Gigawatts.   This will require six thousand times the current annual production at  1,000,000 Megawatts per year.   This will require an investment of some 40 billion pounds per annum over twenty five years.   A huge, but achievable budget.
We cannot afford to wait around.   All the signs are that we need to act now.   Improvement in the efficiency and durability of systems will indeed strike the core economics, but without practical experience now, we will not tackle these improvements in time.

Area of PV cells compared to Australia
The above map shows the area of PV cells of current efficiency (10%) required to supply ALL the WORLDS current energy requirements (electrical/transport/heating!). The RED area shows the area required if the efficiency approached 100%.

Richard Monkhouse, updated 19/2/2000.

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