Saturday, 2 June 2012

Electric Cars


Electric cars in stables at Pollok Park


Glasgow is a compact city.  Nowhere in the city is much further than 10 miles from any where else.  It is perfect for electric vehicles(EVs) which typically have a short range.

Pictured above are two of the forty electric vehicles being trialled by Glasgow City Council.  The trial which began over a year ago is scheduled to run for three years.  The vehicle fleet operated by the City Council comprises over 1200 vehicles of which over 350 are cars or car derived vans with the remainder including everything from small vans to bin lorries, minibuses and even articulated lorries.

This is surely a welcome measure to reduce the city's carbon footprint and improve air quality. Or is it?


The trial EVs are a mix of Peugeot Partner Electric Vehicles, pictured, and Nissan Leafs.The Peugeot does not appear to be a standard production model, hence data on their expected performance is not readily available.  There is more information on the Nissan Leaf, which indicates that it has a range of 109 miles on a 30.3kWh charge, based in typical driving conditions.  This works out at 0.28kWh/mile which leads to carbon emissions of 144g C02/mile(90g/km), based on the typical UK energy mix for electricity generation of 0.52kg/kWh. At a unit cost of electricity of 12p/kWh the running cost can be estimated as 2.1p/km.

Compare this with the most common car in the fleet, the Volkswagen Polo Blue Motion, of which there are almost 200.  This has rated carbon emissions of 89-91g/km, almost the same as the electric car. The urban fuel consumption is 67mpg or 4.2l/100km. At £1.40 per litre this works out at 5.9p/km which is almost three times the running cost of the electric vehicle.

The conclusion therefore is that there is no benefit in climate change terms from using electric vehicles compared with the best performing diesel cars at the current time, with the latter spending much less time being refuelled - the leaf takes 8-12 hours for a full charge.  The EV has a lower fuel cost than the diesel car. Both of the cars fall in to the zero rate for Vehicle Excised Duty but at a cost of £16,000, the VW Polo Blue motion is about £10,000 cheaper than the Nisan Leaf. This price difference means that the EV only breaks even financially after about 150,000 miles.

The only advantage of the EV at this time is that the pollution caused by them is displaced from the city to remote power stations, which may help to improve the city's poor air quality.

Strathclyde University are to conduct a review of the first year of operation in order to give feedback on their performance.  The results of this study would be useful for car developers, helping identify aspects that could be improved, and could also help other large organisations to gauge whether the low emission EVs would be suitable for their fleets.  It would be interested to know whether their energy use matches predictions and whether they keep their charge or spend too long out of use being charged.

There are many other issues which must be considered before EVs can be written off as overpriced underachievers.  If, as hoped, our electricity production becomes less fossil fuel dependent then the carbon emissions from EVs will drop.  On the other hand, if there is another dash for gas, especially shale gas, they will be worse.  If EVs become more common, they could collectively act as electricity storage to smooth out the peaks and troughs in variable renewable energy supplies but we also need to consider the whole life carbon cost and the impact of extracting rare earth metals for the batteries.



Related Links:
Information on GCC vehicle fleet, from FOI request: http://www.whatdotheyknow.com/request/vehicle_fleet_list_79
Nissan leaf Information on typical energy use: Nissan website
VW Polo Blue Motion fuel consumption taken from the Energy Saving Trust website

5 comments:

  1. Your post is a breath of fresh air in more ways than one!
    First of all, it's so reasonable for a city to take on a fleet of low-carbon cars: it sets the standard for the rest of us. I wish more cities would do this in the US.

    Since I'm a certified geek, I like your levelheaded, numbers-based analysis on the EV debate: we need more of that, and less emotion in the discussion. I agree with you that it's hard to beat the new generation of frugal turbodiesels, and those Polos are one of my
    favourites! (unfortunately, also not for sale in the US - for now).

    I haven't yet given up on the EVs: yes, they are expensive now, but it's early days (remember when a 16kB floppy disk cost more than $100?). I've a feeling the price will come down - especially as EVs like the Leaf are overly muscled, designed that way to show that they are not to be classed with golf carts. Once we're over that, they will offer EVs with more modest engines: those will be cheaper. And EVs the size of a Polo will be more frugal than the larger Leaf.

    Like you, I also believe that there is tremendous potential for EVs to act as energy storage devices. The technology already exists for supply-dependent metering, where you pay very little for wind electricity during a storm, and a lot more in windless periods. Better yet, your charger gets switched off when the wind dies down (or the sun sets), unless you over-ride that. That kind of infrastructure really needs to be initiated by a government, whether local or national.

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    Replies
    1. I agree that the capital cost is likely to drop significantly over then next few years . I also believe there needs to be a radical rethinking of what an EV needs to be: it does not need to be the same as a traditional car and could be redesigned from the ground up to reflect the role that it can fulfill.

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  2. Good post giving us a lot to consider. Thank you! I am a new follower from Meet & Greet.
    Huge green hugs,
    Pat

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  3. NOTE: The comparison of carbon emissions above adopts standard values for electricity (which may or may not include supply chain emissions) and uses only the exhaust emissions of the diesel car. I have read that emissions of a petrol car can be around a third higher when the supply chain is considered, i.e. extracting, refining, transporting/distribution and retail of the petrol. Embodied carbon from manufacture has not been considered.

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    ReplyDelete