Gore’s film ‘An Inconvenient Truth’ tries to raise consciousness of the threat of global warming caused by CO2 levels in the atmosphere. I’m just becoming aware of the significance of another change – no more oil.

Have a look at Peak Oil. The modelling done by Hubbert back in 1956 turned out to be very accurate. Many nations (including the UK) have already passed Peak Oil. It would be irrational to suppose that reserves in Saudi Arabia are effectively infinite. So all the data  predicts that somewhere in the next 3 decades, we will run out of oil and gas.

What would it be like in developed nations without a car? How would you get to work? What would then happen to suburbia? You can live without working, but not without food. How would food be distributed to supermarkets? Prior to that, how would food be produced without agricultural machinery? Tractor engines have 400 horse power – what farm has 400 horses? Where do the insecticides and fertilizers come from? What does that imply for current world population levels?

So you need an alternative energy source – wind/tidal or nuclear. Biofuels could not be produced in sufficient quantity – not that and grow food (see last paragraph). But that is needed within the next 30 years at the most. How long does it take to design and build a nuclear power station? How many in the UK currently have approved plans? None.

If you could produce sufficient nuclear power quickly enough, vehicles would need effective batteries – or fuel cells at a reasonable cost. That might come to pass, with a lot of R and D. Maybe. Otherwise.. well, nothing that I know of. Hydrogen maybe, but you still need power to produce it. Most people snigger about electric cars. I know they don’t work very well. But they are about as effective, in terms of range and speed, as a horse. And that will be the only alternative.

But what about nations which do not have nuclear power? What will happen to them? In that light, what do the ambitions of Iran look like?

On the positive side – no global warming. That’s OK then.

Just reading something by Obama, set me to wondering whether it was possible to meet energy requirements from ethanol from plants. So I did some calculations (and some statistics gathering thanks to Google). The numbers refer to the USA:

The power from sunlight (the solar constant) is about 1.4 kW/m²

This is if the sun is overhead – away from the equator maybe we get half this – 0.7 kW/m²

Changing this to Joules of energy per year, you get about 2 X 10¹⁰

The growing season might be half a year, so that is 10¹⁰ Joules per year – on a square meter.

Suppose plants convert sunlight to fuel with an efficiency of 10%. This gives us 10⁹ Joules per year on a square meter.

So how much land is needed?

Total energy consumption of the US in ‘liquid form’ = petroleum, diesel etc is 40 quadrillion BTU, which converts to 4 X 10¹⁹ Joules per year.

So we need 4 X 10¹⁰ square meters of land. How much have we got?

The US has about 940 million acres of agricultural land, which is 4 X 10¹² square meters.

So only 1% of agricultural land could meet energy needs. If the conversion efficiency is down to 1%, that’s still only 10% of the land.

So they are reasonable.