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Was: Moss/Lichen on roof, now we are into pollution.
Jaques d'Alltrades wrote:
The message from The Natural Philosopher contains these words: And just how do you think electricity to charge the batteries is produced? With a loss approaching 30% at every stage: thermal value of fuel for power station to power delivered at charger (taking in power loss in transmission lines), charging the accumulator, discharging the accumulator all taken into account, the net result is a great deal more pollution to propel your so-called clean electric vehicle. Well first of all, because it isn't 30% at every stage. Thermal efficiency of a modern power station is up to 65% - more if you can use the waste heat to e.g. heat water for the neighborhood. Elecricity generators and motors can achieve over 90%, and transformers etc are typically around the 95% plus mark. At optimum levels, and only the very best and most expensive - and how many manufacturers use that sort of quality of component? Its not that hard. Efficiency is mostly about using bigger dimensions of wire and iron for a given power: Wire and iron is not expensive, and in power generation it is sensible to spend a few extra quid to save a few thousand a year on fuel costs. The tackiest electric motors I have are no worse than 50% efficient - better than an IC engine. I am not sure on distribution losses. Theortecically those can be as low as you like, by use of fatter or supercinducting cables. Superconducting cables can be as low as zero (for 99,99% pure niobium at liquid nitrogen temperatures), but the environmental cost of keeping them in the superconductor range would far outweigh the gain. My extensive experience of charge/dishcarge of secondary cells suggests that 90% convesrion or better ins not uncommon. The big things in favour of all electric cars tho are (i) the initial electricity generation can be done by many different things - from windmills to nuclear power stations, as well as burning non fossil fuels (biomass) But burning hydrogen, or even a hydrocarbon in an internal combustion engine will still be less polluting. Well no it isn't, because it produces water vapour at the least in the car, secondly the hydrogen has to be produced - from electricity. If you look at the overall energy equations, you use more to generate hydrogen from electricity than to generate the electricty. Also, as I said, distributing hyrogen requires a whole new infrastructure, Its not safe to do it in a simple tanker. Nor can it simply be stored in underground tanks. (ii) its a lot easier to scrub atmospheric pollutants from a power station flue than from a car exhaust. That doesn';t affect the hydrigen versus electric car argment tho. Then what happens to the scrubbed-out pollutants, I wonder? Well, one of the ways of getting rid of Co2 from burining e.g. oil that has nbeen proposed, is to put it back underground. Atomically, pollution is a zero sum game. We had all that carbon in teh ground, and no one worried. Now its in the air and we do. Its used up atmospheric oxyhgen (and hydrogen does that to make water) and so depending on wthere the lower oxygen or higher CO2 is the problem, you can e.g. make carbonates and bury em. Essentially scruvbbing power stations flues makes thungs like sulphuric acid - useful in luquid form, bad in teh air - and nitric acid. This is BETTER than buring in a car where all teh issues raised make it innecicient and expensive to remove, but not ideal. I think we need to look at this iin a sensible perespective. There is nothing wrouong witha hydrogen car, if hydrogen were just lying around waiting to be burned, except that eventual;ly you would use up all teh ocygen in teh air. At least with burning carbomn, we know rthat plants eat teh stuff and release oxygen... Hydrogen and electric produce on teh one hand just water, and on the other hand nothing, as waste products, used as fuel, at the point of usage. BUT when it comes to teh energy analysis of producing electricity and hydrogen, and distributing them, as far as I know the only way to mass produce hydrogen is by electrolysis. So the hydrogen has electricity as its starting point anyway, and cannot be 100% efficient in generation. And te storage of hydrogen is non trivial. The only reason hydrogen is being considered is because it can be burned in not-too-different- cars. The car industry is amongst the stupidest and most conservative there is. They are only thinkning of teh least investment to produce the next lump of tin that will 'meet regulations'. WE I hope, are talking about saving energy, and lowering global pollution. When you look at it, actually the tidiest thing is nuclear. Produces no pollution at all, apart from warm water, apart from that niggling litle problem of radioactive spent fuel and things what got near it. Crack that one and you are away...it may be that in the end we have to acept it as the lesser of many evils. And incedentally, scrubbing pollutants from that volume of exhaust gas requires a gigantic investment in plant and running power, and it's my belief that that investment will never 'repay' the amount of energy/pollution required for its construction. Well, that depends on legislation doesn't it? In the micro scale. On the macro scale saving the planet might be worth it? If for example you calculted that teh loss of property and erosion of coastlines diue to gl;obal warming was costing the inusrance industry say 50 nubillion a year, then teh insurance companies might decide to fund the costs themselves...out of sheer self interest. Or the givernments decide that the taxpayer should bear the cost, and get it back in reduced insurance premiunms. Etc. (iii) we already have an electrical distribution system that has huge off peak energy availability. And that is precsiely when we would be charging our cars up. Essentally tow electrckettles overnight is all it takes power wise, to get a full days motoring (unless you intend to drive to scoitland, in which case the electric car uis stll not able to cut teh mustard, although it is feasible to fully rechage current cells in about one hour at e.g. a specially equipped 'service station' I've said it before in another forum: if you bothered to use a spellchecker, your posts would be readable. It takes too long to reply yo one of your posts point-by-point. That is the neatest way of ducking out of a losing argument I have ever seen. /rest of it snipped. Life is too short/ And thread killed. |
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