Green car question

[srebbe64]

Read in the paper that some electric Vauxhall (Ampera??) has zero emissions for the first 50 miles. However, surely if a car is powered by electricity then it's plugged into the mains - which is largely fossil fuel generated (coal or whatever). Anyway, this got me thinking. What is the 'real' difference between petrol/diesel carbon emissions and electric? I'm thinking that an internal combustion engine generates more noise and heat - so is not as energy efficient. But by how much?

[thinfourth2]

Nothing is zero emissions including cycling if you look at the whole life cycle of anything you do.

However an electric car is zero tail pipe emissions which is nice in a city if it wasn't for the distinctly not zero emissions buses

[Caulkhead]

Professor David MacKay has done some interested calculations on this:

"Over the course of 19 recharges, the average transport cost of this G-Wiz is 21kWh per 100km – about four times better than an average fossil fuel car. The best result was 16kWh per 100 km, and the worst was 33kWh per 100 km. If you are interested in carbon emissions, 21kWh per 100 km is equivalent to 105 g CO2 per km"

So on average a tiny little G-Wiz puts out the same CO2 as most small diesel hatchbacks, they just put the carbon somewhere else.

[Jasandjules]

srebbe64 said:

However, surely if a car is powered by electricity then it's plugged into the mains - which is largely fossil fuel generated (coal or whatever).

Yes but that doesn't fit in with the lie so they call it zero emissions and just ignore the elephant in the room, along with ignoring the building of the car and shipping it around the world etc....

[thinfourth2]

Caulkhead said:

Professor David MacKay has done some interested calculations on this:

"Over the course of 19 recharges, the average transport cost of this G-Wiz is 21kWh per 100km – about four times better than an average fossil fuel car. The best result was 16kWh per 100 km, and the worst was 33kWh per 100 km. If you are interested in carbon emissions, 21kWh per 100 km is equivalent to 105 g CO2 per km"

So on average a tiny little G-Wiz puts out the same CO2 as most small diesel hatchbacks, they just put the carbon somewhere else.

But you aren't comparing like with like

For the g-wiz you are taking the CO2 from the fuel going to the power station, being converted into electricity and then delivered into the G-wiz

For the hatchback you are taking the CO2 from fuel in the tank of the car and being converted into forward motion. While ignoring how the fuel got into the fuel tank. So you are ignoring the oil rig drilling the oil, the oil tanker taking the crude to the refinery, the refinery refining the oil, the product tanker taking the oil to the fuel depot, the lorry taking the fuel to the fuel station and the pump pumping the fuel into the car.

To be fair you must either include the whole process of getting the fuel into the diesel car or you must assume the electricity magically appears in the batteries of the G-wiz.

[kambites]

srebbe64 said:

Read in the paper that some electric Vauxhall (Ampera??) has zero emissions for the first 50 miles. However, surely if a car is powered by electricity then it's plugged into the mains - which is largely fossil fuel generated (coal or whatever). Anyway, this got me thinking. What is the 'real' difference between petrol/diesel carbon emissions and electric? I'm thinking that an internal combustion engine generates more noise and heat - so is not as energy efficient. But by how much?

Internal combustion engines under typical usage directly driving the wheels are generally of the order of 20-25% efficient.

Internal combustion engines running at peak efficiency charging a battery are about 40% efficient, but loss in the generator, batteries and motor, push the efficiency of an overall range extender type system running from petrol power down to about the same.

For power stations, it obviously depends on the fuel. Modern gas are about 50% efficient, coal ones about 40%. The grid isn't particularly efficient though and again you have to take into account the losses in the car itself, so you're probably looking at a similar figure again. Of course if you're talking about CO2 output, nuclear generation can cut that figure dramatically.


The biggest advantage that hybrids have over direct drive engines is that they can reclaim energy when slowing down that would simply be lost as heat in the brakes in a normal car. Once you include cost of manufacture and recycling/disposal, the picture just gets far too complicated to be able to put a figure on.

Edited by kambites on Tuesday 13th September 10:01

[ewenm]

thinfourth2 said:

an electric car is zero tail pipe emissions which is nice in a city if it wasn't for the distinctly not zero emissions buses

Those zero city emissions are appealing to me but as you say, without buses leading the way, "urban black snot" will continue. It does make me wonder about the green convictions of various UK urban councils and the government - if they truly wanted to make a difference wouldn't they be mandating electric public transport?

Oh, of course, that would require investment wouldn't it?! Can't be having that now Espeically when "public" transport is run by private companies.

[kambites]

Some cities have been switching to electric public transport, at least partially. It's hard to do with buses because they drive almost constantly so have no time to recharge (I assume you couldn't get enough batteries in them to last the day) but trams have been making a comeback in recent years and they're generally electric.

[Caulkhead]

thinfourth2 said:

Caulkhead said:

Professor David MacKay has done some interested calculations on this:

"Over the course of 19 recharges, the average transport cost of this G-Wiz is 21kWh per 100km – about four times better than an average fossil fuel car. The best result was 16kWh per 100 km, and the worst was 33kWh per 100 km. If you are interested in carbon emissions, 21kWh per 100 km is equivalent to 105 g CO2 per km"

So on average a tiny little G-Wiz puts out the same CO2 as most small diesel hatchbacks, they just put the carbon somewhere else.

But you aren't comparing like with like

For the g-wiz you are taking the CO2 from the fuel going to the power station, being converted into electricity and then delivered into the G-wiz

For the hatchback you are taking the CO2 from fuel in the tank of the car and being converted into forward motion. While ignoring how the fuel got into the fuel tank. So you are ignoring the oil rig drilling the oil, the oil tanker taking the crude to the refinery, the refinery refining the oil, the product tanker taking the oil to the fuel depot, the lorry taking the fuel to the fuel station and the pump pumping the fuel into the car.

To be fair you must either include the whole process of getting the fuel into the diesel car or you must assume the electricity magically appears in the batteries of the G-wiz.

I realise that the CO2 figure for the ICE vehicle does not include the emissions related to digging up the oil and refining it and transporting it, but where does is say that the figures for the EV do include digging up the coal and taking it to the power station?

[ewenm]

kambites said:

Some cities have been switching to electric public transport, at least partially. It's hard to do with buses because they drive almost constantly so have no time to recharge (I assume you couldn't get enough batteries in them to last the day) but trams have been making a comeback in recent years and they're generally electric.

It could be Trams in flat cities and Trolleybuses in hilly cities (recouping energy on downhill sections and not necessarily requiring constant connection to the wires). All pie in the sky of course.

[thinfourth2]

Caulkhead said:

thinfourth2 said:

Caulkhead said:

Professor David MacKay has done some interested calculations on this:

"Over the course of 19 recharges, the average transport cost of this G-Wiz is 21kWh per 100km – about four times better than an average fossil fuel car. The best result was 16kWh per 100 km, and the worst was 33kWh per 100 km. If you are interested in carbon emissions, 21kWh per 100 km is equivalent to 105 g CO2 per km"

So on average a tiny little G-Wiz puts out the same CO2 as most small diesel hatchbacks, they just put the carbon somewhere else.

But you aren't comparing like with like

For the g-wiz you are taking the CO2 from the fuel going to the power station, being converted into electricity and then delivered into the G-wiz

For the hatchback you are taking the CO2 from fuel in the tank of the car and being converted into forward motion. While ignoring how the fuel got into the fuel tank. So you are ignoring the oil rig drilling the oil, the oil tanker taking the crude to the refinery, the refinery refining the oil, the product tanker taking the oil to the fuel depot, the lorry taking the fuel to the fuel station and the pump pumping the fuel into the car.

To be fair you must either include the whole process of getting the fuel into the diesel car or you must assume the electricity magically appears in the batteries of the G-wiz.

I realise that the CO2 figure for the ICE vehicle does not include the emissions related to digging up the oil and refining it and transporting it, but where does is say that the figures for the EV do include digging up the coal and taking it to the power station?

So you agree you aren't comparing like for like

[Caulkhead]

thinfourth2 said:

Caulkhead said:

thinfourth2 said:

Caulkhead said:

Professor David MacKay has done some interested calculations on this:

"Over the course of 19 recharges, the average transport cost of this G-Wiz is 21kWh per 100km – about four times better than an average fossil fuel car. The best result was 16kWh per 100 km, and the worst was 33kWh per 100 km. If you are interested in carbon emissions, 21kWh per 100 km is equivalent to 105 g CO2 per km"

So on average a tiny little G-Wiz puts out the same CO2 as most small diesel hatchbacks, they just put the carbon somewhere else.

But you aren't comparing like with like

For the g-wiz you are taking the CO2 from the fuel going to the power station, being converted into electricity and then delivered into the G-wiz

For the hatchback you are taking the CO2 from fuel in the tank of the car and being converted into forward motion. While ignoring how the fuel got into the fuel tank. So you are ignoring the oil rig drilling the oil, the oil tanker taking the crude to the refinery, the refinery refining the oil, the product tanker taking the oil to the fuel depot, the lorry taking the fuel to the fuel station and the pump pumping the fuel into the car.

To be fair you must either include the whole process of getting the fuel into the diesel car or you must assume the electricity magically appears in the batteries of the G-wiz.

I realise that the CO2 figure for the ICE vehicle does not include the emissions related to digging up the oil and refining it and transporting it, but where does is say that the figures for the EV do include digging up the coal and taking it to the power station?

So you agree you aren't comparing like for like

No, I don't agree to that. To do so I would need more information. If both figures exclude the cost of fuel extraction and transport then I am comparing like for like, if one does and one does not, I am not.