We’ve just spent a day on Tromso, an island where the inhabitants have in theory a carbon negative life-style because their energy co-operatives own wind turbines that export surplus electricity to the rest of Denmark. However the people of Tromso still drive, they are burning the black stuff and emitting CO2. Many eat meat and import food with all the embedded carbon that implies. So they – like all of us – have an absolute impact on the planet. Where they differ is that their export of clean energy reduces the impact (carbon emissions) of others. But they are not actually living a low carbon lifestyle. And this is my fundamental problem with carbon trading – at least in its present form. It can allow people to say their life-style is carbon negative when it is in fact no such thing. To be fair to the people of Tromso, they are working on a new plan to electrify their islands transport, and in their co-operatively owned energy biomass and wind energy plant they are providing social as well as technical models for a low impact, low carbon society. So don’t get me wrong, I think what they have achieved as a community is marvellous, but even they haven’t yet gone far enough on the path to low-impact living.
A problem with carbon trading
10 06 2010
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“It can allow people to say their life-style is carbon negative when it is in fact no such thing.”
That completely misses the point. You seem to be taking a personal moral point on this when the aim of carbon trading is to reduce the total amount of CO2 emission. If people can offset their consumption by displacing other carbon consumption in other parts of the world (in this case by reducing CO2 that would have otherwise been emitted by electricity consumption) then that is perfectly valid. You might argue they could use less by going vegetarian, travelling less and so on, but that applies to everybody. These islanders are in the fortunate position that they happen to be in a community which has the natural resources (wind) to do it. To that extent its unfair of course – but the same holds true if you are an Icelander with access to geo-thermal.
However, where there is a real problem is in the detail of the accounting. There are lots of carbon off-set schemes (like planting trees) which are highly dubious, not to mention bio-crops. Then there is the problem that wind power is, by it’s nature, highly intermittent and has to be backed up by more reliable power generation systems which cannot always be stopped and started at will. There will be some CO2 savings, but they are not going to be as high as the proponents claim with the standby capacity that has to be kept ticking over at sub-optimal efficiency levels. All this extra equipment
What would be much simpler is a simple carbon tax. To make sense it would have to be charged world-wide or you just get CO2 emissions displaced (so the CO2 used in the making of your computer parts is now generated in China, not Europe). That way it provides an advantage to those places which use less CO2 in production.
nb. the makers of your car play fast and loose with statements of the relative thermodynamic efficiency of their vehicles compares with internal combusion engines. What they do not include in the figures is the thermodynamic efficiency of the electricity generation cycle, including distribution with a realistic generation mix. We aren’t yet (if ever) in the idealised world of 100% CO2 free power generation, and you can’t just cherry pick “our car is powered by the wind”. That roughly halves their claimed relative efficiency.
I thought I’d add some supporting numbers to my previous comment (which I can’t see yet) as to why the Think City claims can be misleading. Note that this applies to all electric cars, not just this one. This is a quote off their site
“When comparing the electrical engine with a traditional combustion engine, the difference in energy use efficiency is striking; whilst an electrical engine uses 85-90% of energy to run the car, the combustion engine utilises only 20-25%. Most of the energy provided from petrol, diesel or even bio fuels disappears as heat. ”
The fallacy here is that they are completely disregarding the thermodynamic efficiency of the electricity generation/distribution and, I rather suspect, the inescapable energy loss in the battery recharging cycle. In fact most of the primary energy disappears as heat in any thermal power station.
The following reference estimates the thermodynamic efficiency of the UK generation and distribution system which comes out at 31% against the primary energy sources.
http://www.powerwatch.org.uk/energy/graham.asp
Even if things have got a bit better in the 10 years since this was produced (and any gains are likely to be modest – the basic laws governing thermodynamic efficiency provide for some fundamental limits) then this puts a whole new complexion on the efficiency of electric cars powered from the national grid.
Taking the best figure Think City claim (and ignoring the power loss in the recharging cycle) then we get an overall efficiency of 31% x 90% = 28%. If you add in the loss in the recharging cycle, then that is going to drop to 25% or worse which gets close to that for a conventional car (20-25%). Of course you also have to add in the distribution and refining of petrol or diesel, but those are (relatively) modest, so we are probably comparing something like a 20% thermodynamic efficiency if the conventional car with 25% for the electric one against primary fuel sources. That’s a gain – but it’s not three times more efficient.
It’s also worth comparing the CO2 emissions (in a UK context) as a cross-check. I’m using the government sanctioned long-term average figure of 0.43Kg of CO2 per kWh (although the current figure is over 0.5Kg). Of course it will be a lot lower in countries blessed with ample, reliably renewables (like Norway and Iceland) or extensive nuclear (eg. France), but we can’t just magic these up in the UK; we have to use what is likely to be the mix of generation in the medium term. In the US, China and much of central Europe the CO2 emissions per kwH are a great deal worse than the UK.
According to the Think City specifications it takes 14A at 230V for 13 hours to go from 0 to 100% charge. To be generous I will assume that the 160km claimed range can be achieved on the 85% charge cycle which is only 9.5 hours or 31kwh.
So that would give 31 x 430/160 = 83 gms/km (at current UK generation mixes it would be almost 100gm/km).
To take a modern, efficient e conventional car which is notably larger, faster and likely to be cheaper to buy, consider the Ford Fiesta Econetic 1.6 TDCi DPF 3 door. According to official figures that produces 98gm/litre (there are hybrids which do better).
In other words, the real difference between electric cars and the most efficient conventional cars of similar size is nothing like as great as the manufacturers claim, at least in a UK context. There will be more of a benefit to the electric car in town (as stop-start suits electric better than internal combustion), but much of that will disappear on the open road. If the manufacturers of conventional cars did want to sacrifice all to fuel efficiency, then they could do a great deal better than even this.
Of course if we do start generating large amounts of surplus renewable off-peak electricity and we can have smart metering (when the storage capacity of these electric cars will be useful), or if we go massively nuclear, then it will change these numbers. However, if anybody is expecting these small electric cars to make any notable difference to the nation’s energy usage or CO2 emissions in the medium term, then I fear they will have to think again.
If you want efficient urban transport, get yourself a bicycle. In fact an electric bike is more efficient than a human powered one when the costs of producing the extra food you burn off is taken into account.