Naked Science Forum
General Science => General Science => Topic started by: Geezer on 01/07/2010 05:15:52
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At one time there were power stations in Ireland that burned peat for fuel. I don't know it they are still operating or not.
Anyway, would peat be viewed as a fossil, or a renewable, fuel, and if it's renewable, should Ireland and Scotland use it as an energy source?
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It would probably be classed as a fossil fuel though probably not strictly fossilised in geological terms. The length of time for renewal is far too long for it to be regarded as a renewable resource. It releases trapped CO2 so is no better that other (true) fossil fuels in this regard.
There are several peat burning power stations in Ireland - some quite large. I don't think there are any in Scotland but I could be wrong.
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If the amount burned each year were less than or equal to the amount formed, it would be like burning trees (renewable, carbon neutral). Peat forms very slowly, however, so that's unlikely. In which case it would be like burning coal or oil (effectively finite resource, releasing trapped CO2 from long-dead organic matter).
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Rosy, I know you didn't mean to say that trees can be thought of as practical renewable resource for general energy use, but rather an example of something that was carbon neutral. However, it prompted me to look at some statistics:
World energy use is a little over 2kW per capita
UK energy use is a little over 5kW per capita
USA energy use is a little over 10kW per capita
1kW = 1kJ/sec
I wondered how many trees it would take per year to support a continuous 2kW of power even if this could be converted into a suitable form with 100% efficiency. 2kW is, surprisingly, quite modest and equivalent to a small fire (in a fireplace) burning continuously. I could not find any pertinent statistics but I would guess that this would be about 1 log of about 1 foot long by 4 inches diameter every 2 hours or so. This would imply using a suitably cut tree trunk 30' by 1' diameter every 7 days. Clearly more usable biomass could be harvested from smaller branches etc, so perhaps this would be improved so as to use of a modest tree every 3 weeks. This would imply 17 trees per year for everyone on the planet (85 trees if you live in the USA).
In practice the wood from the trees would be harvested sensibly, but it would imply that we would need to plant trees at this sort of rate.
I do think it shows how far we are away from finding a complete solution to maintaining energy usage whilst being carbon neutral though.
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Graham - quite so.
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This may sound slightly "off the wall" (a speciality of mine [;D]) but the lawmakers (aided and abetted by the technologists) have "done a number on us".
We actually might be a lot better off if we were still burning trees, peat and even coal in open fires, and spewing noxious fumes from our cars. (WHAT?! Geezer has obviously blown his only remaining gasket.)
Think about what happened. We were being choked to death (literally) with smog and pollution in the major population centers, so the lawmakers said this had to be cleaned up. The technologists obliged and found inventive ways to eliminate enormous amounts of the local pollution produced in large cities like LA and London.
And the result was that LA and London, and everyone else, was able to export their CO2 pollution throughout the planet. Everybody noticed how much cleaner the air was, but in reality, the even bigger problem had been swept under the rug.
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Your right as far as CO2 is concerned, except where nuclear power plays a role. But the main reason for banning coal burning etc. in cities had nothing to do with CO2 but to do with the noxious other stuff that was seriously damaging to health - especially when concentrated in a localised region. The large power stations not only disperse the other gases better but also burn much more efficiently so as to produce a lower percentage of CO and particulates. Nowadays many will also have measures in place to remove other gases too.
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Your right as far as CO2 is concerned, except where nuclear power plays a role. But the main reason for banning coal burning etc. in cities had nothing to do with CO2 but to do with the noxious other stuff that was seriously damaging to health - especially when concentrated in a localised region. The large power stations not only disperse the other gases better but also burn much more efficiently so as to produce a lower percentage of CO and particulates. Nowadays many will also have measures in place to remove other gases too.
That's exactly my point. The localized regions cleaned up their acts, but they didn't appreciate that the consequences of their actions would have global implications. Basically, they solved their local problem by turning it into a global problem.
If they had attacked the the problem from a perspective of energy consumption only, I think things would be very different. However, they didn't. They simply moved the problem around.
BTW, I'm not claiming that any of this was apparent to me at the time. I just think we should consider these things in the future.
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Environmentalists have been heard to say in recent times that 'it's a shame that CO2 has no colour or odour'. The implication being if it had, like smog then populations would have sat up and forced change.
Ironically, in the days of pea-soupers there was a visible signal for CO2 along with NOx and soot - ie, you didn't get one without the other!
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Peppercorn - I agree with the point that CO2 is easy to ignore. But I am curious, if CO2 had an 'odour' wouldn't we have grown so used to it by now that we would no longer recognise it.
what I really mean is , I think, that odour is subjective - if we have receptors for a volatile chemical it has an odour, if we don't have receptors then it is odourless. Maybe someone better informed could confirm or deny, but I don't think there is an independent property of a chemical that is odour. well off the point...
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Absolutely - Peat is not renewable on a practical basis as in an active bog, it forms at a rate of 1- 5 mm per year. It also has a lower energy density than most other fossil fuels (so carbon wise is more costly to transport). Finally when a bog is in good condition it is an active carbon sink. There are a number of projects in the UK trying to restore degraded bog to a favourable condition.
There may be further disadvantages in burning "dirty" fuels as soot (or in the climate change jargon terms "black carbon" (as opposed to what?!?)) has been identified as a possible source of arctic melting as it both absorbs heat and reduces albedo. Of course, sulphate aerosols particularly from the burning of low grade coal have a cooling effect, although they have other detrimental environmental effects (acid rain)...
There is a moral question about the western nations externalising our pollution to other countries, but that is an argument for another day...
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Peppercorn - I agree with the point that CO2 is easy to ignore. But I am curious, if CO2 had an 'odour' wouldn't we have grown so used to it by now that we would no longer recognise it.
My earlier statement about what it would be like to live in a world where CO2 was detectable (particularly in excessive amounts) is meant more as a reflection on the psychology that drives our societies - where there is more resistance to tackling an unseen threat than to a tangible one.
As an aside: Carbon monoxide is trace in the atmosphere but is highly poisonous in moderate quantities and our senses have no way to detect it for our protection. [could be an interesting thread to start on why humans have not evolved a sense for this...]
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There is a moral question about the western nations externalising our pollution to other countries, but that is an argument for another day...
China is catching up fast. They are putting cars on the road at an incredible rate.
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A thing to remember is that exporting the production to China has exported the pollution, although the toxins are being reimported in the food you eat and the cloting and materials coming back. Look at the current melamine in milk and such scandals, the toxic toys and drywall, the pet food that kills your pets, and many more.