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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorSimonH
    • CommentTimeJun 30th 2008 edited
    I know – it’s not about building and is cars again, but at least I’ve got it in the right forum. I though tyou greenies and cost saving experts might be interested in this one…

    I currently drive an old BMW 330Ci and want to switch to something lower polluting. However I have realised that selling it won’t get rid of it’s emissions. In fact they could make it worse – depending on who has the car next (I drive it very slowly!). After looking at hydrogen or electric conversions I have realised they’re not economically viable (or even available) and went back and had a look at LPG – something I discounted previously as I only do about 7,000 miles per year.

    Now I’ve done some calcs and found that LPG is not only cost effective but also very low emissions. In fact so low, it makes me wonder why we have diesel/petrol?

    I found for my 7,000 miles per year the 330ci with an LPG conversion will have:

    Emissions of a Ford Focus Econetic Hatch (1882kg 330ci vs 1860kg Econetic)
    Fuel Costs of a VW Polo Bluemotion (£745 330ci vs £764 Bluemotion)

    As a comparison the Toyota Prius came in at 1,557 kg and £805.
    The 330ci currently on unleaded petrol is 2,324 kg and £1202 yikes! In fact its worse as it drinks super unleaded – same emissions as unleaded but about £1.20 / litre.

    These are based on real world consumption figures – mine for the 330ci and www.spritmonitor.de for the two “Eco cars” from Ford and VW. I guessed these will be better than average figures as anyone bothered enough to post their fuel figures will probably drive sensibly.

    Here’s my conversion figures if anyone wants to check. Is this too good to be true!? Instead of shelling out -£4-5k to “upgrade” to a low emission car, I can just spend £1,800 on an LPG conversion. And I’ll know that when I do come to sell the car on – at least it will do less damage.

    Litres -> Gallon 4.54609188

    Petrol Diesel LPG
    £/Litre £1.19 £1.25 £0.59
    £/Gal £5.41 £5.68 £2.68
    kg CO2/L 2.3 2.63 1.49
    kg CO2/G 10.46 11.96 6.77

    Focus Econetic 45 mpg.
    Polo Bluemotion 52 mpg.
    Toyota Prius 47 mpg.
    BMW 330Ci 31.5 mpg (currently with unleaded) 20% less for LPG = 25.2 Mpg.
    (all well below manufacturers claimed figures except for mine)

    Get your mileage and divide and times the above figures a bit by fuel type/mpg to see how you’d come out.

    One thing it shows, that MPG isn’t the best thing to go on. Diesel gets more MPG but costs more and has higher CO2 per litre. Plus a whole load of other nasties.

    The thing that swings it for LPG is the very low 1.49 kg/CO2 per litre – I think because there’s more Hydrogen than Carbon in the propane (C3H8) / butane (C4H10) mixture and than you get with the complicated unleaded : C7H16 C8H18 C6H12 C5H10 C6H6 C7H8 & C2H5OH C4H9OCH3 etc. Even though the energy density is lower it’s more than enough to make it the lowest emission fuel.

    And the lack of TAX – which I can now see is more than justified based on the [lack of] emissions.
    Too many sums for me but I was wondering if you had considered the chip fat option as well?
    • CommentAuthorSimonH
    • CommentTimeJul 1st 2008
    Yikes no! It's a petrol car - which would mean bioethanol, but after everything I read about that recently - I think it would be more environmentally friendly to run it on mashed up bunny rabbit and birds eggs. Or it would be more humane to go and shoot africans to save them starving to death as the food organisations can only afford 1/2 the relief they bough last year because grain/corn prices have double due to the amount being used in cars (especially the US). Apparently a tank fill up is about the equivalent of a years food supply for 1 person! So that climate vs people equation doesn't balance when it comes to bioethanol.

    Why is life so complicated?

    • CommentAuthorgreenman
    • CommentTimeJul 2nd 2008

    I haven't checked your figures, but as the driver of an lpg converted car myself I did the sums myself before diving in, and can confirm them in principle.

    I think there are two points: Firstly, yes, for as long as we're 'forced' to be dependent upon the internal combustion engine, lpg is probably the greenest of the fossil fuels you can use to power one. Apart from the relative benefits you mention, I believe lpg is a byproduct of the oil industry and therefore presumably doesn't require significant energy to produce it (unlike petrol and diesel and the energy used in the refining process).

    This leads onto the second point - green, in this context can only be relative, as we're still talking about fossil fuels. There are non-fossil fuels that can power an ICE which are therefore theoretically greener (even given your points above), such as hydrogen, methane, and so on, but unfortunately these are not readily available in a usable form, so perhaps it's unfair to compare them to lpg...

    Hopefully, this question will become redundant in the near future if the major car manufacturers stick to their plans to release electric cars onto the market over the next few years. If the cost of batteries can be brought down to a reasonable level then price per mile via electric car will be so much cheaper than by ICE that market forces (and the price of oil) will make all other considerations academic!
    I did mean recycled chip fat actually but I see what you mean about bio fuels. Thanks to USD 7 billion in Federal subsidies 25% of the US maize crop is being diverted into ethanol and the investors are piling in. To get good crop yields the farmers naturally use fertiliser (which is made from the oil the ethanol is supposed to replace) - a cunning wheeze that ...
    • CommentAuthorgreenman
    • CommentTimeJul 3rd 2008
    There's another possibility being researched at the moment - biofuel from algae. Algae can grom in water that is unfit for any other purpose (including salt water), can double in volume in a matter of hours, and of course like other biofuel crops consumes CO2 in the process.

    On a slightly different subject, a few years ago when climate change was still barely registering on the radar for most people I saw a documentary about huge swathes of algae that grow in the word's oceans each year. These algal blooms increase in size proportionately with the water temperature, so increasing global temperatures should see a corresponding increase in algal blooms.

    I don't want to suggest that this could be the answer to all our prayers (much though I'd like to believe it), but this seems to me to be a potential mechanism for the planet regulating CO2 levels and temperature. Individual alga consume minute quantities of CO2, but in the trillions (as exist in these blooms) they consume more than the world's rain forests. Of course their life cycles are short, so some of that CO2 is released back into the atmosphere again quite quickly, but perhaps not all.

    Going back to the fuel question though, if a viable means of harvesting algae from these blooms could be found then that could give you an almost limitless (and at least renewable) biofuel.
    A little comment about biodiesel... It is not all bad stuff. I run my Passat on biodiesel made by Sundance Renewables (www.sundancerenewables.co.uk) from used vegetable oil. So much more eco friendly than bunnies. It is lovely and clean, and I get no drop in performance. Have to drive a lot for work, and was a greener way of doing that. The price at the moment is around £1 a litre. That will have to go up substantially soon, as the big Agri companies are jumping on this bandwaggon and buying it up, and Sundance are finding really hard to get enough oil. Good recycled biodiesel should be supported in our local communities wherever we can. I think that most of the used vegetable oil from this country gets collected and transported to Germany to make... er... biodiesel!
    Perhaps we should try and keep it here.
    • CommentAuthorSimonH
    • CommentTimeJul 3rd 2008
    Er, yep - not so "wonder fuel" - but more like "Least bad fossil fuel that's readily available".

    RE: The algae stuff - shell have a good write up on this in their website - to quote their old adverts "you can be sure of shell" getting involved in anything that may keep them in business in the years to come.

    It' has occured to me - that the fossil fuels we are using now, are actaully the long dead ancestors of the algae that are blooming now, not just due to increased sea temperature - but also increase CO2 levels in the air - now 370ppm and used to be 250-350ppm (max).

    It seems that they might actually provide the solution, so that we don't have to wait for the dead algae to fall to the sea floor, get covered in silt, placed under extreme pressure and heat for a few million years, trapped in an inverted U and then spend millions drilling them and piping and refining them. Instead - we can just "squash and wash" them to extract the oil as they make it. Renewable oil? There's a quandry - how do we get CO2 levels back down if we have released all the fossil CO2? and then keep recycling it.

    There's a guy in the UK who's developed a system to trap the CO2 in your exhaust in a box, empty said box into a "algae processing unit" at your home which then produces biodiesel which can be reused to refill your tank!! He's got some contacts to help develop it now, so we may see some major news on it soon!

    • CommentAuthorgreenman
    • CommentTimeJul 3rd 2008
    Yes Simon - it does sound like a hopeful line of research (the algae I mean - don't know about the exhaust mounted CO2 trap).

    As to how we get the CO2 levels down - well perhaps that's the algae again - after all, they are a natural form of carbon(dioxide) capture. As the planet (and therefore the oceans) heats up, the algae will multiply to a point where their numbers will exceed our ability to use them up. At that point, as long as we're no longer burning fossil fuels, the CO2 levels might begin to drop.

    Despite all this talk of bio-diesel, I still believe that electric transport is the future. That will mean that CO2 production levels will start to fall anyway (assuming CO2 capture at point of electricity generation, or green generation).
    • CommentTimeJul 3rd 2008
    Wasn't the exhaust mounted CO2 trap recently on Dr Who and used to try and take over the world!
    • CommentAuthoralgae
    • CommentTimeOct 19th 2008
    <blockquote><cite>Posted By: SimonH</cite>There's a guy in the UK who's developed a system to trap the CO2 in your exhaust in a box, empty said box into a "algae processing unit" at your home which then produces biodiesel which can be reused to refill your tank!! He's got some contacts to help develop it now, so we may see some major news on it soon!


    Simon I would like to find out who this guy is, can you pass me his details?

    Open forum or pm.

    Regards, Jim.
    It' has occured to me - that the fossil fuels we are using now, are actaully the long dead ancestors of the algae that are blooming now, not just due to increased sea temperature - but also increase CO2 levels in the air - now 370ppm and used to be 250-350ppm (max).
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