The 5 key elements of sustainable transport

13 04 2014

The 5 key elements of sustainable transport, or rather ‘so called’ sustainable transport makes for interesting reading.  Some of this info doesn’t really make much sense to me…. like the C intensity of different flights (business and economy, short and long) as a function of emissions per kilometre.

Interestingly, the difference between a ‘small car’ (a car that can only do 35MPG is NOT a small car!  But then, this is written in/for the USA….) and a grid charged electric car is only 15g CO2e/km, or just 9%.  By that measure, the Suzuki Alto I drove in Tasmania emits far less than an electric car, unless that car is 100% solar recharged.  And then I’m doubtful, because since we now know solar has a shockingly low ERoEI, it might be even closer than we think.  I’m also surprised cycling’s numbers are as high as they are shown here.  Does a cyclist really consume a whole lot more food than a motorist?

The article also states “People who live in cities have lower transport emissions.  Fuel economy may be lower in city traffic but that is more than made up for by the fact that city dwellers drive far less.”  Well that depends……  since moving from the city to the country, I’ve actually halved how much I drive!  Then it continues with “In 1950 less than 30% of the world’s population lived in cites, by 2010 that figure was over 50%, and by 2030 it is expected to surpass 60%. This natural trend to urbanization is a huge opportunity to for lowering both distance travelled per person and the carbon intensity of that travel.”  Whoever wrote this has obviously no idea cities will eventually be abandoned for being too far from their food sources, and due to the fact that when grids go down, none of the lifts will work!  Nor the sewerage……..

Shrink That Footprint


Transport is responsible for around a seventh of greenhouse gas emissions globally. Of these emissions almost two thirds are the result of passenger travel while the rest is due to freight.

So passenger travel is a big deal for climate.

In the chart above, which comes from our new eBook Emit This, we compare carbon intensity of different types of passenger transport on a per passenger kilometre basis.  Using it we can explain some elements important to the development of a sustainable transport system.

1) Fuel Economy

Our chart today compares the carbon intensity of different transport modes, per passenger kilometre.  The better fuel economy gets the lower emissions go.  If you just look at the cars you’ll see the large car (15 MPG) has emissions almost three times that of the hybrid car (45 MPG).

By improving fuel economy we can get the same mileage while generating fewer emissions.  Something that is achieved by making engines more efficient, vehicles lighter and bodies more aerodynamic.  But even then combustion engines remain relatively inefficient and produce emissions at the tailpipe, so improving them is really just a stop-gap en-route to sustainable transport.

2) Occupancy

The cheapest and simplest way to lower the carbon intensity of a passenger kilometre is to stick more people in the vehicle.  In each of the figures above car occupancy is assumed to be an average of 1.6 passengers (including the driver).  But most cars are designed for 5 people.

If you take a look at the bus examples the importance of occupancy becomes even more stark.  The local bus example has emissions seven times higher than the school bus.  While there routes may vary a little they are both diesel buses.  The main difference is that the school bus has very high occupancy.

With notable exception of flying public transport tends to have quite low carbon emissions, due largely to having relatively high occupancy.

3) Electrification

In the absence of breakthroughs in second generation biofuels electrification is the most important pathway to low carbon transport.

Electric cars using low carbon power have footprints less than half that of the best hybrid, even after you account for their larger manufacturing footprint.  Right down the bottom of our chart is the high-speed EuroStar rail which used low carbon French electricity. Though not on our chart the lowest carbon transport on earth is probably electrified public transport in a place like Norway where electricity generation is almost carbon free.

While there is a natural tendency to obsess about the electrification of cars, there are lots of interesting innovations occurring in the electrification  of rail, motorbikes, scooters and bikes.

4) Pedal power

They may be a bit low tech for some, but when it comes to carbon emissions bicycles are pretty cutting edge.  Even when you account for the foodprint of excess energy used when cycling, the humble bike is incredibly low carbon.

Bikes have obvious limitations around speed and distance, but for short trips in places with good infrastructure they are hard to beat in terms of carbon. They also have a great synergy with public transport systems like intercity rail.

5) Urbanization

Each of the first four elements we have described above refers to improving the carbon intensity of transport.  But emissions are a function of both how we travel and how far we travel.  One thing that tackles both of these issues is the trend towards urbanization.

People who live in cities have lower transport emissions.  Fuel economy may be lower in city traffic but that is more than made up for by the fact that city dwellers drive far less.  Electrification of public transport is more economic and practical in cities.  Occupancy on public transport systems is much higher.  And access to infrastructure for both cycling and walking is often better.

In 1950 less than 30% of the world’s population lived in cites, by 2010 that figure was over 50%, and by 2030 it is expected to surpass 60%. This natural trend to urbanization is a huge opportunity to for lowering both distance travelled per person and the carbon intensity of that travel.

Those are our five elements of sustainable transport: fuel economy, occupancy, electrification, pedal power and urbanization.

Check out our free new eBook Emit This for more ideas on getting more life out of less carbon.

Source: Shrink That Footprint. Reproduced with permission.



7 responses

13 04 2014

With urbanisation, the issue is the kind of urbanism. Large sprawling cities of the kind we build in Australia encourage the most driving. We need tight, small cities built up to 5 storeys, laid out with business below and apartments. Some urban farming is possible but I think urban and rural separation will always exist.

13 04 2014

Look…. I agree. But the trouble is, it’s not what we have. So we have to build it…. and building anything requires more energy and resources and by default, more emissions…. which is why I’m not a great fan of ‘transition’. We have to do more with less, not the other way around.

13 04 2014

We’re building anyway. Even in economic and resource decline, we will continue to build.
I can fully understand how you would drive less now than when you lived in an Aussie metropolitan area though.

13 04 2014

Yes, we’re building now….. because we still can. But look at what happens to cities in decline…. and this is NOW!

13 04 2014
Coachman on the Box

America needs to get out more.

14 04 2014

Look at all that vacant land between the buildings! Veggie gardens! Potential. I agree, it’s about learning to use what we have and making the most of what we already have to work with. We’ve done a great ob of screwing up the planet and are now doing a spuerb job of saying “we have nothing” but what we have is the wrong perspective.

And as for bikes… I think they can take us as far as the imagination allows (this is not for me I will admit but even so)

15 04 2014
Mulga Mumblebrain

‘Everything is possible’, you just need to do it. Look at Cuba, when the ghouls in Mordor on the Potomac thought it was about to finally be crushed after the cirrhotic Quisling Yeltsin destroyed the Soviet Union against the wishes of 80% of the population. Cuba just got to work, and survived, while the former Soviet was looted by the Usual Suspects and entered a twenty year Depression that continues to today in Ukraine. I think that walking ought to get very great emphasis, for health benefits, to and from hubs of electrified transport, or to local schools, shops, etc. Mini-buses there must be, for the infirm, but two or three kilometre trips either way would be quite easy particularly as you grow fitter. It gives a chance to natter with neighbours, too. One thing that a truly sustainable society will have to do is SLOW DOWN, to reduce the speed and the intensity of life. Less is more when it is less stress and frantic filling in time with ‘productive’ (Newspeak for destructive) activity.

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