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From the Library Shelf:
Proud Co-Founders of Transition Town High Wycombe
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The LPG Car
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It was in Mayer
Hillman's book on "How we can Save the Planet" that you can read
all the terribly bad news about LPG. This topic really has
become quite a football between the deep green environmentalists
and pro-LPG lobby. In this article we will attempt to cut
through all the figures thrown around to get down to some hard
facts.
What we turn up is
quite encouraging. As you would expect, the truth falls
somewhere between the two camps. LPG is nowhere near as bad as
some say, whilst the Installer Community may be guilty of
inadvertently bending the truth a little. Either way LPG remains
a great investment, whilst it lasts... |
What the Papers say...
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In our roundup
of the Top Ten Cars to buy in the UK, based upon lowest CO2
emissions, we recommended the LPG Smart Car. We bemoaned the
fact that this car is somewhat in the shadow of the Toyota
Prius. However we are not alone in noticing this hidden
star. The Independent Newspaper in their series "Your Planet
and how you can save it" judged the LPG Smart as the best
available beating the Prius and G-Whiz Electric Car. The
Smart is also eligible for a 100% discount from the London
Congestion charge. |
Going Green - Installer
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at www.goingreen.co.uk:
"..compared
to other similar size small diesel/petrol cars, smart lpg
particulate emissions (the 'soot' that gets in to and on
your body) are 90% lower and CO2 emissions are at least 20%
lower at just 93g/km CO2 for the fortwo and 110g/km CO2 for
the forfour. lpg is less than half the price of unleaded
petrol, on average 57% less per litre. In addition a smart
lpg costs just £30 per year in road tax and is exempt from
the congestion charge... Used smart lpg fortwo are available
from £7,999 (inc VAT) for the fortwo and from £10,795 for
the forfour. New smart lpg start at £9,200 for the fortwo
pure. If you have an existing smart car, the conversion
costs £1,999 plus VAT.... smart forfour - four seats, more
space for work or the school run (103 mph, 60 mpg combined
cycle).. smart fortwo coupe or cabrio - the classic two
seater, only cleaner.... (84 mph, 60 mpg combined cycle)...
The lpg tank is installed underneath the car, in the cavity
between the floor and underbody cover. So no tank in the
boot, and no impact in the interior of the vehicle. The
petrol tank has been reduced in size slightly to accommodate
the lpg tank, and sits in the same space..." |
Conoco Phillips - Fuel Supplier
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Here is what
they have to say at
www.conocophillips.co.uk:
"A litre of LPG can cost less
than 40p a litre, while petrol - thanks mainly to fuel duty
- now costs up to 86p a litre. A typical, quality petrol
engine conversion costs about £1,800, depending on the car,
and your payback will be about 18 months, depending on your
mileage.... In addition to its financial attractions, LPG is
also a cleaner fuel than petrol, and dramatically cleaner
than diesel. Compared with petrol, LPG vehicles emit about
20% less CO2. While LPG emits similar levels of CO2 to
diesel, one diesel car is equivalent to 20 LPG cars with
regard to nitrogen oxides (NOx), and 120 LPG vehicles in
terms of particulates, both of which are major causes of
ground-level air pollution. One important environmental
caveat with LPG is that it actually uses up to 20% more fuel
by volume than petrol. It is simply a cleaner way of burning
a fossil fuel, not a way of reducing the need to drill for
oil.." |
VCA Car Fuel Data
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The Government
Agency that provides independent testing of Car Makers fuel and
emissions figures. They are the prime source for any numbers.
Sadly they do not assess LPG Conversions. If they do the numbers
are not available. They say this "The different fuels have different merits from an environmental perspective. Compared to petrol, diesel vehicles have significantly lower CO2
emissions per kilometer traveled because of the higher efficiency of diesel
engines and hence have a lower impact on climate change. Diesel vehicles also
emit lower levels of CO and HC than equivalent petrol vehicles.
However diesel
engines emit greater levels of NOx and Particles than new petrol vehicles. As
mentioned earlier, emissions of such pollutants are an air quality issue,
particularly in urban areas. LPG and CNG cars are generally converted from petrol fuelled cars, either by the
original manufacturer or an aftermarket converter. For practicality, CNG and LPG
vehicles tend to be bi-fuel, meaning they can run on either petrol or the
gaseous fuel. LPG vehicles tend to fall between petrol and diesel in CO2
performance. This is due to the lower carbon and higher energy content by mass
of the fuel. CNG offers even lower CO2 emissions than LPG, typically
comparable with diesels. Local pollutant (CO, HC, NOx and Particles) emissions
performance of well engineered LPG
and CNG vehicles is similar to a petrol vehicle or slightly better." |
Norfolk County Council
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Norfolk County Council completed unique 12 month operational
trials of various alternatively fuelled vehicles comparing these
with control vehicles. The main fuels tested were
Hybrid-electric, Liquefied Petroleum gas (LPG), Bio-diesel in 5%
mix with ULSD and Bio-diesel in 20% mix with ULSD. The full
report is in the course of completion, but project manager
Stuart Hutchinson says; “Although the trial data is
being fully analysed at the moment – and obviously the final
report should be read in its entirety – there are a number of
things we have learnt during the course of the trials that are
apparent from even from the most cursory glance at the trial
data.
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When comparing the annual averages for
all the main trial vehicles for five main pollutants, the
top five vehicles, by a long way, were all LPG. This is even
more revealing when you consider that there were only 5 LPG
vehicles in the trials and they represented 3 different
makes of vehicle
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Mileage for LPG vehicles was variable and
very much depended on the use that the vehicle was being put
to. However, the data has shown that LPG still represents
value for money given that it is currently half the price
(or less) of diesel or petrol
For more information and to order a copy of the full report email
altfuel@norfolk.gov.uk. |
The Energy Savings Trust
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"LPG = 10 to 15% reduction in CO2 well to wheel and is on a par with diesel....
with 30%
lower running costs. Figures for CNG identical."
We checked these numbers
against VCA Car Fuel data for Bi-Fuel Vauxhalls from 2000 and
these did support a 12 to 16% improvement. |
2003 Emissions Testing
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Here is a link to a
supposedly independent "2003 European Emissions Testing
Programme" Summary of Results. They tested 26 vehicles with a
variety of Diesel, Petrol and LPG. For CO2 emissions this says
that "Petrol CO2 is 20.3% more than autogas" in their
'Artemis' real world drive cycle and a well-to-wheel basis. A
copy of the full report is available from
www.lpga.co.uk.
Many installers
claim that LPG saves 20% CO2 over petrol. However, look at the
numbers above again. The 2003 Emissions Testing Report doesn't
say this. The actual figure is that Petrol produces 20.3% more CO2 than Autogas. Sadly, due to a
statistical anomaly this means that LPG actually produces 16% less than Petrol.
Well to wheel is actually only 16 to 18% Once again, if we dig out some old
Vauxhall bi-fuel numbers from over five years ago from VCA Car
Fuel Data then, based upon Tailpipe emissions, it is only about
10 to 12%. Keep in mind that CNG Volvos (2006) yield a
wapping 21% saving so there is a lot of variability in the numbers and who is
testing against what test standard. |
Performance
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One more bone of
contention. The critics say that LPG reduces car performance by
20%. It isn't clear where these numbers come from. Sure the
calorific value is lower but then more of it is used. By volume
you use 20% more. One installer I spoke to quoted a 5% reduction
in performance. We read elsewhere (the Greenfuel Company) that
it was only 1 to 2%. It is certainly very small. Hardly
surprising when when actual users claim that they hardly notice the
difference. Indeed, this is largely a matter of perceptions. You
don't move to LPG to improve your speed or acceleration. Hence
few users care. The drop in performance is marginal but you
clean up on emissions and costs savings. It is also claimed that
LPG powered cars are quieter and that LPG reduces engine wear. |
Diesel versus LPG
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Whereas VCA Car Fuel
Data and Mayer Hillman try to convince us that CO2 emissions for
LPG fall somewhere between Diesel and Petrol there is no
evidence to bear this out. Most other sources quote CO2
emissions as comparable. The 2003 Emissions Report states quite
clearly that "Diesel CO2 is 1.8% more than Autogas". Even
clearer is the evidence showing the Diesel Nitrogen Oxides are
over 2000% more than Autogas. Hydrocarbon savings are 40% whilst
Carbon Monoxide savings are 35% over Diesel. |
The Bottom Line
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LPG is a bi-product
of oil extraction and refining and comes primarily from the
North Sea. It used to be flared off as a waste product. The UK
produces 6.4 million tonnes every year and is a net exporter of
this product. The UK is therefore self sufficient in LPG and has
enough to power 6 million vehicles annually. As a result supply
and pricing is not subject to volatility in the Middle East or
Russia and has never been interrupted by refinery and fuel
strikes. LPG converted vehicles produced after 2001 receive a
road fund licence discount of up to £20 per year in the UK. Some
installations on some makes are exempt from the London
Congestion charge. Whilst converting to Autogas will not
forestall the end of fossil fuels it does give us more a
breathing gap and reduces CO2 emissions. To learn more go to
www.boostlpg.co.uk |
Conclusion
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| References: |
- See individual references quoted in the above article
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