David Hansen wrote:
On Mon, 28 Jan 2008 09:18:54 +0000 someone who may be The Natural
Philosopher wrote this:-

Yes, now do the 'maths' mary - you may need to take of your socks,
because the numbers sometimes go above ten, and see how MUCH you really
saved.

Excellent, personal abuse.


Ditto.

After your hilarious comments about 'religion'

This whole topic is too important to be left to touchy feely qualitative
analysis.

If people can't do the maths and the real analysis, they shouldn't comment.

Its like going into the supermarket, and buying tow to get one free..and
then letting it rot in the cupboard. That isn't saving money. That's
being a gullible fool.

Which by and large is what most people who buy so called 'green'
products, are.

BECAUSE its something I consider important I HAVE spent a total of
several MONTHS looking into 'green' technology and the like, doing a LOT
of sums, and double checking the results.

Using strict cost benefit analysis both in cash and energy terms.

And frankly the answers are depressing and scary. Almost none of it
makes a measurable difference to overall carbon footprint, and a lot of
it actually makes things worse, and the one thing that actually DOES
have the potential to make a real positive difference is shouted down by
religious greenies. On QUALITATIVE grounds. It makes them FEEL BAD.

Let's take solar power.

The UK is about 30M hectares in surface area.

A hectare is 10K square meters, so thats 300G meters square.

WE have a peak winter energy consumption as a nation, of around 300GW.

In winter, the average insolation is less than 600Wh per day, or 25W/sq
meter.

That means we need to totally cover the entire area of the UK with solar
panels at 4% efficiency, to generate our energy needs.

In summer, when we don't need the energy, its a lot less. But that's no
great help is it?

In terms of cost, a decent nuclear power stations is around £1000 a Kw.

So unless that one meter square solar panel is actually costing less
than around £2.50 (at 10% efficiency)..its money better spent elsewhere.


Its also rank hypocrisy, or naivete of the first order to claim that you
personally are 'green' when everything you use , eat buy and consume, is
produced by a system that isn't.

As I pointed out to the woman in the checkout at the 'green' till in
Waitrose, that the plastic used in one carton of cream was ten times the
amount in the plastic bags used to carry the shopping home in. Howevr
all I got was teh blank incomprehension of those that don't like to be
told that they are basically involved in a futile feel good marketing
exercise, and their cherished beliefs have no more chance of stopping
global warming than fitting a CFL bulb does.

Its only by doing the nummbers, that you can actually whittle down the
bull**** to what really actually DOES save energy and works.

We have juts had a thread on wood burning, and the US contributor and I
both came to a reasonably similar figure that 5-10 acres per house is
what it takes to heat a small home, sustainably.

There are about 30M households in the UK.Pretty staggering for a country
of 60M people, but that's apparently the way it is. 10 acres is arond 4
hectares, so we would need to devote something like 120M hectares to
wood growing just to heat our houses. Thats 4 times the total land area
of the united kingdom. Right. Great idea.

The latest greatest windmill projcet, a '1GW' windfarm at a cost of
£1.5bn, won't actually produce 1Gw at all. Since thats its PEAK output,
when the wind is exactly the right strength. Typically it will produce
about 15% of that. Average. Which makes it about 4 times as expensive AT
LEAST as a nuclear power station. To do the total country copmplete
energy needs, we need about 1800 windfarms JUST like it. A staggering
conclusion.

Never mind the cost issues of maintaing all those windmills out there in
the sea..

Whereas we can run the WHOLE COUNTRY, on just 100 5GW nuclear power
stations.

The simple answer is this. You need a staggering amount of kit - often
exceeding the total area of the country, to collect the very low energy
density energy from 'renewable' energy. I.e. energy from the sunlight we
get, whether its biofuel or direct solar. Or windmills, or water power.
We are a society that actually uses something like 10% of the
equivalent energy it gets from all the sunlight falling on it, to keep
itself running. Whilst with excruciatingly expensive technology we might
reduce that a little, we cannot slash it in half, or anything like it,
at the population density we have. Nor can we contemplate slashing the
population in half either.

We have built this society by using energy - energy borrowed from
natures piggy bank of fossil fuels. It's running out. If it is NOT
replaced, we will revert to the sort of lifestyles and population levels
of - say - Tudor England.

No renewable energy source has the sort of levels of energy we need to
counteract this: we have no geothermal energy to speak of, we have some
possibility of using some tidal energy, but at massive adverse and
unknowable effects on tidal ecosystems.

Using natures Stellar piggy bank and raiding the fusion store, gives us
a few hundred billion years of energy, but we cant yet do it
economically, if ever.

The ONLY thing we have left is a couple of million years of nuclear
fission energy.

Its not the best solution. Its the ONLY solution.

Nothing else can replace fossil fuels in the UK. Not one other
technology has a *prayer*, even. Windmills are a distant ugly and hugely
expensive second best. Maybe in practice they might to 10% of the job at
enormous expense and totally transform the whole nature of the seascapes
and landscape in so doing.

Solar power has its place in sunnier climes. Stuck in a low population
low latitude desert, it starts to make sense. Not a lot, but some.

I don't have any axe to grind in this apart from simply not wanting to
be involved in the sort of chaos and civil war that would accompany the
return of the UK to a pre industrial society. I have no involvement with
the power generation industry, or any other industry, I am not part of
any lobby or group.

I simply did the sums, using the facts as available, not as wishful
thinking. I wish we did NOT have to contemplate nuclear power. But at
least its problems are practicably soluble, Whereas that doesn't ring
true for any other way to crack the nut.

Certainly not any technology that relies on direct or indirect solar
energy falling on the UK landmass. There isn't enough of it.

In fact, there is a puzzle, in that the earths actual temperature is
more than can be accounted for by the solar radioation and its initial
temperature post formation, leading to a lot of speculation that it is
in fact a large fission reactor in its own right.

So you may owe the life of the planet to nuclear reactions anyway. Makes
it a bit stupid to worry about siphoning off a little to heat your
tootsies doesn't it?