Nissan Leaf - Hidden Emissions

Monday 22nd March, 2010
After reading this piece, please see my updated "One Year Later" article.

Following the Nissan Leaf running cost article I wrote last week, I've had a number of people asking about its Green credentials and what kind of carbon footprint it might create for a potential owner. I thought I may as well get my calculator out and do some more sums.

Just to clarify, the Nissan Leaf doesn't have a combustion engine. It doesn't have an exhaust pipe. It's just a milk float style vehicle that is charged from the owner's electricity supply. So driving the car creates no direct emissions and it's CO2 output could be considered as nil, but not if that electricity is sourced using fossil fuels.

If, like me, you're based in the UK; you'll find that the majority of your electricity comes from traditional Coal fired power stations. We do have a bit of nuclear and a bit of wind power but, overall, most of it is generated using steam turbines powered by burning coal and emitting CO2. For this reason, many people have been buying electricity saving devices for the home. For example,  Bye Bye Standby allows you to quickly and easily turn off the power to appliances in your home remotely. This reduces your electricity bills and helps save the millions of kWh of electricity wasted each year by appliances left on stand-by unnecessarily. The same electricity you were trying to save will be used to power your electric car.

@NeilatNissanEU tells me "using electricity to power cars remains vastly less polluting than petrol" but is this the case for owners of the Nissan Leaf in the UK? For "normal" cars, taxation is usually calculated using CO2 output figures. This applies to both VED and company car BIK calculations. Drivers of a hybrid, like me, have discovered that driving a low emission hybrid vehicle can save the owner a lot of money in this area as a result. The Nissan Leaf, being electric, is regarded as not having a CO2 output, exempt from London congestion charges and, presumably, will have zero car tax. But what if we factored in that CO2 output from electricity generation? Well, let's do the maths.

I'll be using figures from the National Energy Foundation (NEF) who have a rather handy CO2 calculator on their site. Using this, and the numbers from the running cost article, we will easily be able to create an equivalent figure for grammes per km CO2. This may allow green drivers to make a more informed decision before buying their next vehicle.

As you likely already know, the Nissan Leaf battery pack stores 24kWh of electricity which provides a max range of about 100 miles. According to the NEF calculator, generating 24kWh of electricity in the UK creates approximately 13kg of CO2 emissions. So, with a bit of simple maths, that's 13,000g for 100miles or 130g per mile of CO2. There are 1.6km in a mile so 130/1.6 = 81.25g per km CO2.

So 81.25g of CO2 per km for a Nissan Leaf on a warm sunny day that doesn't require the air conditioning. Don't get me wrong, this is still very low emissions, and fully establishes the Leaf's green credentials but, if electricity usage increases by just 10%, due to the heater, air-con, headlights, radio, going uphill etc. then it's CO2 output will be no better than the physically larger 89-92g/km Toyota Prius and it's 800+ miles range. It's certainly not "vastly less polluting" in my eyes.

As with the running cost calculations I did last week, I personally think that the Leaf may be too big a compromise for too small a gain. Sure, when we switch to more renewable sources of electricity and our power supply generation becomes greener, then things will be different - but I see this as being over a decade away. The government were recently giving people cash incentives to scrap 10 year old cars so, using that as the lifetime of a car, I don't see the current generation Leaf ever being a viable option for me.

Next time you see a website claiming "zero emission" think again.

  1. 1) David Ferrabee Said: (24/03/2010 17:15:00 GMT) Gravatar Image
    Nissan Leaf - Hidden Emissions


    I humbly submit that maybe a pro-Prius bias is coming through? So a few questions that you can surely dispatch quite quickly:

    1. How does the current Prius fare against the first ever Prius?

    2. Can you not foresee further improvements in both cars that moves all greener transportation in the right direction?

    3. With these and other choices available, should people still be buying fully petrol-combustion cars, now and in the future?



  2. 2) Ben Rose Said: (24/03/2010 17:43:07 GMT) Gravatar Image
    Nissan Leaf - Hidden Emissions

    I wouldn't say "pro-Prius" as such, more "pro-today". A hybrid car is no longer new technology, it's been around for quite some time now and the Prius is the best known and best selling of the available hybrid models globally.

    In "green" papers I often see comparisons between new vehicles and standard ICE models. Being an eco-advocate, I see standard ICE as being "yesterday", I see hybrid as "today" and I look forward to tomorrow. If you are launching a car in 2010, it's only right to compare it to other models that were launched around that time. The most recent one being the 3rd gen Prius. It's not a bias at all, just a realistic comparison with the competition. If somebody launches a new "green" car with claims like "zero emissions", it seemed only right to compare it with the benchmark vehicle in this area. Most of the eco studies I have read also use the Prius in this way.

    To answer your questions:

    1) I've no idea how the current Prius fares against the first ever Prius. Back then I was unmarried, had no kids and was a young tearaway in a highly inefficient Mazda sports car. I've only taken interest in hybrid/eco cars in very recent times. I'm guessing your angle here is that the Leaf is the first of its kind and that things may well have improved considerably by it's 3rd gen model? If so, isn't that like releasing a Black & White TV today and then saying "but how good was the first TV"? People buying a TV today expect 1080p HDTV and a full colour depth.

    2) I can foresee many things but I'm comparing today with today, not today with tomorrow or today with yesterday. I'm simply comparing this new Nissan Leaf car with available alternatives. The Prius is actually bigger and a class (D vs. C) above and it would likely be more sensible to compare with the new Toyota Auris hybrid but I just went for a known vehicle to make it easier for readers to comprehend.

    3) As I indicate above, I regard ICE cars as yesterday. Hybrid vehicles (and now EVs) are today and plug-in Hybrids can be included in tomorrow. I try to avoid saying what people "should" be driving as, for example, if I had my way I'd ban diesel cars for being noisy, polluting nastiness that is likely causing increased asthma and other related diseases in children. But it's not good to be opinionated like that as even my wife drives a diesel and she's usually got our baby in the back so it would be utterly hypocritical to suggest such a thing.

  3. 3) Steve Said: (20/05/2010 14:18:43 GMT) Gravatar Image
    Nissan Leaf - Hidden Emissions

    "if electricity usage increases by just 10%, due to the heater, air-con, headlights, radio, going uphill etc. then it's CO2 output will be no better than the larger Toyota Prius and it's 800+ miles range.

    I would assume your prius with the same devices active will probably become less efficient.

    TBH the major green advantages of producing EV's are not things that will make your average consumer buy. That is the major problems with most green power sources is reliability. What we need to raise above 10% green energy is to have a massive storage capacity in order to provide power when it's needed. if all of the 20 million cars on the road were tesla's they would have the cappacitance to run the UK for a full day (assuming demand is about 43000MW). Or 2 days if we go 50% nuclear even without any co2 generation at all. shove in some standby gas generators and you get a lot more. What's more they get it for the price of second hand batteries.

    Second benifit is if you know you have a range of 100 miles (rather 50 mile round trip) and this became common practice for everyone people would adjust their lifestyle to live more locally taking public transport when they need to travel long distances.

    Additionally if you read the blurb you will see that your 13kgco2 figure is a bit high and i closer to 10kgco2 which works out as 63g/km

    the prius is rated at 104g/km which is a marked improvement

  4. 4) James B-T Said: (10/06/2010 13:39:13 GMT) Gravatar Image
    Nissan Leaf - Hidden Emissions

    Ben, I'm suprised that you haven't taken the opportunity since Steve's comments above to correct him on the emissions of the current Prius which are actually 89 - 92g/km (depending on size of alloy wheels).

    With the plug-in Prius round just round the corner, your reasoning suggests that the UK isn't ready for this innovation either. Is the efficiency of the plug-in Prius better than the Leaf? Toyota are unlikely to suggest that this new vehicle is "greener", if the math doesn't support the claim.

    Great blog BTW.

  5. 5) Janni Said: (13/11/2010 14:45:54 GMT) Gravatar Image
    Nissan Leaf - Hidden Emissions

    I think you got the calculations for the Prius a bit wrong, because you have not added the CO2 emmissions that was done before the petrol reached the petrol station. The well to weel... We have:

    - Exploration

    - Drilling

    - Pumping

    - Transportation

    - Refining

    - Storage

    - More Transportation.

    When you add all these the Prius will have a lot higher emissions than the Leaf.


  6. 6) Ben Rose Said: (13/11/2010 16:51:05 GMT) Gravatar Image
    Nissan Leaf - Hidden Emissions

    But where DO we draw the line here? If you include CO2 for all of those things then you include the CO2 for a lot of other products.

    I went for a walk yesterday and, being a modern human, I wore a pair of shoes. The upper part of those shoes is made from leather, which is made from the hide of cows. Cows spend their days eating grass and expelling methane gas, which is one of THE worst greenhouse gases. Do we factor in the life of the cow when calculating how green my shoes are?

    Worse still, the sole of my shoes is made of rubber. Do you know what they make rubber from? Crude oil. The real heavy fractions of crude oil. The ones that are hardest to refine and take the most energy to extract. Of course, before we refine that, we have to find the crude oil, drill a hole, pump it out of the ground, store it, pump it onto a ship, ship it on massive tankers which burn huge quantities of heavy fuel oil, pump it into storage tanks and only then can we refine it. Then we have to tank it up onto trucks and ship it to the shoe factory, which may even be overseas.

    All that for a pair of shoes? What on earth could the carbon footprint of those shoes be? And the soles even wear out in a year.

    As well as supplying the obvious fuel and lubricants we need, crude oil is also a vital raw material in the manufacture of plastics used in car bodywork, dashboards and artificial fibres for seat materials and carpets. If that'€™s not enough, add in paints, detergents, solvents, adhesives, rubber and even bitumen for tarmac. Whatever fuel we use to power our cars, Crude Oil and refineries are going to be required for decades yet.

    Whilst you may make some valid points about the production of petrol/gasoline, there really is no point in throwing that fraction in the bin whilst we extract other heavier organic compounds.

    In fact, if you look just a little closer, you'll realise that many of the components of the Nissan Leaf are in fact made from Crude Oil - the seats, the dash etc. - we have to refine it to build the car anyway, so we may as well use the fuel part too.

  7. 7) jeffhre Said: (23/07/2011 14:23:04 GMT) Gravatar Image
    Nissan Leaf - Hidden Emissions

    All production cars have seats, a dash, etc. And most drivers may have a few ounces of rubber invested in a pair of shoes vs. 10 or more gallons petrol in a single tank of fuel.

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