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Zero Carbon Leaf drive

The latest episode of Fully Charged raised as many questions as it answered which I am slowly learning is always the case.

Charge times are a very common anxiety. I'll explain as best I can. Using the lead supplied by Nissan which only carries 10 amps, the charge time from utterly empty to totally full is around 10 hours. 

When I arrived at Tellisford Mill, due to the fact that I didn't have the correct lead to take the 440 volt (3 phase) charge (which would have taken around 20 minutes) I plugged in their 13 amp outlet and had to wait around for over 4 hours. To be honest this wasn't a chore, Anthony Battersby and Rachel Feilden who own Tellisford Mill were very hospitable. It was a public open day for them, they are part of the Mendip Power Group which is a group of people who live or own old wool and flour mills along the river Frome in Somerset.

If they had a web page explaining what they're doing I would have posted a link to it, there isn't so I'll do my best.

For a start, filming the actual turbine is impossible as it's buried beneath the mill. The only bit you can see (footage I shot on my phone) was taken in the very cramped room where it spins the actual generator.

The generators output is between 223,000 and 389,000 kwh per year with 330 litres a second passing through the turbine shaft which turns the turbine at a stately 136 rpm but with a torque of 520.6 Newton meters.

This whole set up cost some serious money, (I don't have figures) but they had to re-build the entire mill and dig out the old channel that once fed it, they also had to re-build the Saxon weir (the weir was built about 1,000 years ago) to push the water down the channel and through the mill. However now it's running, they supply all 30 houses in the village nearby and sell power to the grid. The whole project will pay for itself in 10 years and the turbine itself is built to run with minimum maintenance for 40 years. Annual maintenance costs are £120, that's for grease for the turbine and generator bearings. It has to be closed of for a couple of hours a year to enable this process.

Huge amounts of  research have been done to discover if the fish population is affected by the turbine, they have discovered that fish stocks have increased since it's installation, but this is mainly do to improvements done to the weir, which has a fish run, and the trashrack that's fitted before the turbine entrance. This stops all but the smallest fish going through and the ones that do just get a bit dizzy and come out the other end unharmed.

The water flow in the river is not impeded, the way mills were developed over many centuries means they don't increase the risk of flooding, there are many 100's of old mill sites all over the country, including one near where I live, hence my desire to see what they had done.

So now, the Zero carbon claim. I think I made it clear enough. Producing the car, shed loads of carbon, producing the turbine, carbon city, it's a 7 ton steel monster made in Germany and shipped here. The actual energy that actually made the car move, the actual electrons stored in the battery, zero carbon. My argument is simple, you cannot achieve that in an internal combustion engine no matter what you do. The clue is in the name, combustion, burning. There was no burning taking place, the journey back from the mill to my house (68 miles) was my first Zero Carbon journey.

I am having a big slab of photo-voltaic panels fitted to the roof of my garage next month. Massive carbon footprint in production and installation, but once they are there... well, more on that soon.

Reader Comments (26)

Really enjoyed this episode. Had to chuckle over the "range neurosis" invoked by the fact that you were driving a new, unfamiliar EV. That'll abate soon enough, I'm sure.

I wish you would have shown a few of shots of the display in the LEAF before, during, and after charging.

I surmise that the watermill owners were reluctant to appear on camera, as it would have been informative otherwise to hear and see them explaining about their generators output, maintenance, etc.

I can't wait to hear more about the installation and eventual output of your solar panels. I am loving mine (see the link I have provided), and only wish that I already had my LEAF to slurp up all the extra kWh they are generating.

THANKS for the fun episode, "Bobbert"!

look forward to hearing how the panels go with charging your car / house...

April 19, 2011 | Unregistered CommenterJames V

They don't have a website but there is an excellent presentation on the mill by the owner here:


Mark - the owners have been on camera before as they made a short documentary for the Einstein Network. Pity - would have been nice to have them on there in retrospect.

April 19, 2011 | Unregistered Commenterdpeilow

P.S. the Leaf charger is DC - you need a very big and expensive charger to charge it in 20 minutes.

If only Nissan had taken the approach of their cousins at Renault, who will offer 3 phase charging on their cars next year. That is far more simple and cheaper for sites to install for the same end result.

April 19, 2011 | Unregistered Commenterdpeilow

Another great episode Robert. Wished there were old mills here in Australia one benefit of having a lot longer history than the New World.

Looking forward to further information coming on the Leaf, would be interesting to see if Range is affected by load, so does having 5 passengers in it make any difference. Assume you are getting your software updated to fix the issue that is affecting the Leaf not starting under certain circumstances.

With your solar panels do you know what the total KW output will be for them, eg: 1.5, 2, 5? I guess that will be another Fully Charged when the time comes, cannot wait.

April 19, 2011 | Unregistered CommenterTassieEV

I wouldn't worry too much about the embodied carbon in the panels. The energy payback time of solar PV is probably 4 years or less:


(and that is a 2004 publication, it can only have gotten better since then I should think)

Though I don't know what your insolation is like there. I'm in the process of getting a 1.5kW system on the roof and it is supposed to average about 6kWh/day.

April 20, 2011 | Unregistered CommenterAidan

Could you check the figures on the amount of water going through the turbine. On the video you mention 4 cubic metres/sec which would be 4000 litres while above it's 330 litres.

April 20, 2011 | Unregistered CommenterMike McLennan

You can produce zero carbon in an IC engine - you have to use a biological process which takes the carbon from the air in the form of CO2 so it's net carbon neutral. Of course it's difficult, but it might well be possible with genetically modified bacteria.

April 20, 2011 | Unregistered CommenterSteve Jones

I see what you're getting at, but it's not quite zero carbon. As you said it needs 120 quids worth of grease for maintenance. That's refined hydrocarbon.
I know it's a minuscule amount compared to the carbon output of other forms of electricity generation. I only bring it up to point out how pervasive petrochemicals are in modern life. We can and should reduce them as much as we can, but we may never be able to cut them out completely.

April 20, 2011 | Unregistered CommenterGadgetGav

The downside to the Renault method, is they are putting an expensive 3 phase charger in the car. The costs are being transferred from the charging station to the vehicle. Is this a better solution?

I want a less expensive car with more fast chargers. With the LEAF, I get the car for less. With a 3 phase charger in the car, there is a better chance of getting more fast chargers. Decisions, decisions!

April 20, 2011 | Unregistered CommenterKeith Ruddell

excellent comments as usual, thanks for great input.
Now, Mike McLennan, just before I recorded this the mill owners told me that there was 4 cubic meters a second and that's what I was going on. I didn't double check and I should have, the most likely explanation is I misheard what they said. I know the 1 cubic meter drops 1 meter produces i kilowatt is correct, but the total amount of water passing through the turbine every second is now a mystery. When I one day have the money to make Fully Charged with an actual budget I will have a researcher with me who's had a proper eduction and will hopefully help on these very important points.
And GadgetGav, point taken, I should have said 'not absolute zero carbon, but bloody close'

April 20, 2011 | Registered CommenterRobert Llewellyn


1 cubic metre of water (1,000 Kg) with a 1 metre drop has a potential energy of almost 10kJ. That means if there is 1 cubic metre per second then that means 10kW is lost. If only 1kW of electrical power is produced then the generator/turbine combination is only 10% efficient. That strikes me as infeasibly low. Trawling around micro-generator sites, 50% for small installations seems to be more typical. That would mean the 1 cubic meter per second dropping 1 metre would generate around 5kW.

The formula for the power produced is very simple - very basic physics.

P = 9.81 x R x H x E

where :-

9.81 (acceleration dues to gravity in m/s)
R - the flow rate in cubic metres per second
H - Head of water in metres
E - Efficiency of the turbine/generator set (must be < 1)

As an example of a commercial site (at random)


The MHG-1000LH claims to generate 1kW from a flow rate of 0.131 cubic metres/sec with a 1.5 metre head. Plug the numbers and it comes out at about 52% efficient.

So, either the watermill turbine is spectacularly inefficient, or there is something wrong with the numbers.

Those who've done the estimates think that micro-generator schemes might have the potential to generate 3% of the UK's total electricity (note, not power) demands. One problem of course is that river flows are can be highly variable through the year. The river Frome has an average discharge rate through the year of about 2 cubic metres per second, although it has a maximum of 70 cubic metres per second although in some dry periods it can almost stop.

April 21, 2011 | Unregistered CommenterSteve Jones

Yes, that's correct. They told us a wrong number and didn't think to check it. Forgot the approximate x10 for gravity (sorry).

That explains how they are getting more like 40kW from the 4 metres cubed per second. One of those numbers had to be off. That was bugging me all the way home. Damn.

April 21, 2011 | Unregistered Commenterdpeilow

@Keith Ruddell

I think the Renault solution is better at this stage of maturity in the EV market.

We want sites to install fast charging, but with few cars on the road many of them won't entertain it. To get them to do it, cost needs to be as low as possible. Nissan have not exactly been dishing out the chargers.

The Nissan DC chargers are reported to cost up to $25,000 with about the same again in installation costs (I was told that directly by a utility company). To install a 63A three phase socket is about £200 in parts and a couple of hours work.

Many of the cars have high power three phase chargers onboard anyway - it's called the regen circuit. "All" they need to do is beef up the cooling so that it can run at that power level for long periods.

Besides, the Renaults coming with this feature would appear to be cheaper, so it's in the noise for the car cost.

April 21, 2011 | Unregistered Commenterdpeilow

The above presentation says the turbine is 83% efficient. The head is 1.8 metres.

Therefore: 4 x 1000 x 1.8 x 0.83 x 9.81 = 58.6 kW

Hence the mill being said to be 60 kW

April 21, 2011 | Unregistered Commenterdpeilow

Fantastic video, great to see an EV enthusiast driving the Leaf it looks like a great car and fun to drive too. I just wish I could get my hands on an EV with my budget of £10k!

April 21, 2011 | Unregistered Commenterdaveyb


That assumes that the lubricant they're using cannot be replaced with a synthetic alternative, if it hasn't been already. Some of the most sensitive mechanical applications in existence owe their continued function to the often superior performance of synthetic lubricants, and this is "only" a turbine.

Personally, when it comes to weaning ourselves off petroleum products, I think it's our reliance on plastics that'll be the hardest to overcome.

April 21, 2011 | Unregistered CommenterScott Tracy


I was unaware that the traction controller could be connected to the mains to recharge the battery. When I read about the Siemens Charge CP700A charging point, being from Canada, that was the first time I had heard about on-board 3 phase charging. I did some research and only found reference to an upcoming Brusa 3 phase charger that wasn't even listed on Brusa's website. It is difficult to find relevant information, but in a subsequent search I was able to find this, "Powerful AC sources could also be used to charge a traction battery via the traction inverter. In this case the voltage adaption is realised by an off board mains transformer. A broad introduction would severely restrict the possibilities of the vehicle design. Therefore it is used for special applications". It is a 3 year old document, so the situation may have changed.

The Nissan DC fast charger is about $17,900 for the standard model, $18,800 for the cold climate model and $21,100 for the hot climate model. I couldn't find a price on the Siemens Charge CP700A, which is a more relevant comparison to the Nissan charger, but I bet it is much more than £200.

I could see the costs of installing a 63A three phase socket approaching $25,000 if you had to run in a supply line, get a 3 phase transformer, a weather proof service panel, conduit, weather proof outlet box, etc. You still wouldn't be able to charge your EV with that, as the Control Pilot and Proximity Pin would be missing. Those safety features could be circumvented at your own peril.

The Renault EVs are less expensive due to the battery being excluded from the price of the car. However, using the regen capability of the car to recharge the battery shouldn't add much to the cost of the car. It does look like Renault's method of fast charging would be more economical, but not quite as fast as the Nissan one.

April 21, 2011 | Unregistered CommenterKeith Ruddell

Its quite funny that we are going back to medieval power-generating sources and hoping to enjoy a 21st century lifestyle with them! good luck with that project!

April 21, 2011 | Unregistered CommenterWill Bick

also very interested to see the results of installing the PV panels.
Are you planning on charging the car with them? Do you also install some kind of energy storage capacity to go along with the panels?

April 23, 2011 | Unregistered Commentereded

In this video http://abcnews.go.com/GMA/video/nissan-leaf-solution-gas-crisis-13434517 it states that the Leaf costs $32,000 or $20,000 after 'rebates' (presumably government incentives?). That means at today's exchange rate it costs £19,393 in the USA before the rebate and £12,115 after! That a hell of a difference to the UK pricing!

April 23, 2011 | Unregistered Commenterdaveyb

@Keith Ruddell

If the car has a 3 phase motor (e.g. Tesla etc) then the power electronics has to be able to take 3 phase and convert it back to DC when performing regenerative braking. I'm saying that to make that into a charger is not as complex as starting from a blank sheet of paper, totally separate to the regen circuit.

Your splitting hairs over the $25k cost to install a 3 phase socket. You need all that stuff anyway to install a DC fast charger, as I'm sure you know. To make a three phase charging point from a three phase supply basically requires a few $ worth of electronics for an oscillator and a comparator circuit to check the car is present and engage the contactor/relay to energise the supply.

The Mennekes AC system supports up to 50kW (when on a 480V supply in the US) which I believe is the same as CHAdeMO's DC system.

@Will Bick

Except that modern water turbines are about 10x more efficient than their medieval counterparts.

April 24, 2011 | Unregistered Commenterdpeilow

Hi Robert,

If you're getting PV installed then the most efficient method of charging is direct high Voltage DC charging. None of all that messing about with converting the 300V DC from the solar panels to 230V AC via a lossy inverter and then back again to 300V DC through a lossy charger.

You won't need to regulate the current from the PV, as it will be too low to trouble the battery (the max amount of PV you can install for grid tied residential use is 4kW, about 13A at 300V DC). The built in BMS on the battery pack should be able to handle the charging (cell balancing) and an easy mod to allow the DC to be shut off, or better, diverted to the grid tied inverter to sell the excess to the grid is all that is required.

Obviously, Nissan won't have thought of this integration yet, so you'll be stuck with using the 230V AC charger cable fed from the grid tied inverter for the solar.

Me, I've got 2kWp of off grid solar, made from assorted new and second hand solar panels and ex-data centre UPS sealed lead acid batteries hidden under the sofa (I'm a great believer in "re-use before recycle").

I've got a Honda Insight and would be looking in the future to get the battery upgraded, and the firmware hacked so that I can turn it into a plug-in hybrid. I've seen it done with an old crash recovered Prius that was repaired and customised as a plug-in hybrid.

Again, no sense in wasting more carbon emissions buying a new shiny EV car when I already have one - it just needs a battery upgrade and some software mods...

The 10kW electric motor on the Insight is a bit puny, but it's good for 30mph on the flat. A battery that would give it an EV range of, say, 10 miles would be all I need for pootling about town to do the shopping. If I travel anywhere for my job, it's often 135-400 miles a day, so a 100 mile battery wouldn't be any use anyway. I could use it as a petrol hybrid for those trips, and as a pure EV for the 4 mile round trip to town (or even the 1/3 mile round trip to the local supermarket - we'd walk, but with a week's shopping, it's a pain). A plug in hybrid is ideal for me as an only car (my wife doesn't drive and we like going on long road trips).

As it is, my Insight gets up to 75mpg (trip average) on long motorway runs (recently London to York), which is better than the "official" 62mpg and way better than the 35mpg I used to get in my 13 year old 2.2l Honda Accord. That car went to scrapheap heaven in the government £2000 scrappage scheme, and helped me get the Insight. Done over 30,000 miles in it since June 2009 and am delighted with it.

April 25, 2011 | Unregistered CommenterOuttasight


Loved this episode! I have over 6000 miles on my Leaf already and LOVE the car. I also have 6.75kW PV solar on my home. I love that as well! :) You'll love your solar, guaranteed.

@dpeilow, THANKS for the .pdf link. Now I want to find an old mill here in the US and do the same thing!! Sadly, our regulations would cost and arm and a leg. (I loved the pic of the gentleman wearing sandals using the pneumatic jackhammer!! Priceless!)

I have a website for my solar if anyone wants to check it. Lots of info on my residential installation, live generation data, etc. (link should be under my name).

Keep up the good work, Robert!!!

April 28, 2011 | Unregistered CommenterJimmyDreams

I bought an electric car a few months ago, a Cialis actually, and I'm totally disappointed with its quality. It only brought problems to my quiet life.

June 29, 2011 | Unregistered CommenterDwayne 11

Great episode..After reading your views and information i decide to buy new electric car..Thanks for sharing.
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September 30, 2011 | Unregistered Commenterlaurahill

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