Are Electric Vehicles that Green?

[Triassic]

I read in the news that we need to accelerate the take up of electric vehicles to help meet climate change targets, but I’m left wondering are they really that green and sustainable as they are made out to be?. The fuel to power them needs to be produced and the cars appear far more complicated in their components and manufacture. I assume someone has looked at their lifecycle costs and compared them to other forms of powered vehicles?

 

 

 

Edited April 29, 2019 by Triassic

[Crofter]

I can't find it just now but Robert Llewllyn (of Red Dwarf and Scrapheap Challenge fame) wrote a very persuasive blog article on this subject a couple of years ago.

From memory, the jist of it was that even if you take the most pessimistic view, EVs at least give you the option of being powered by renewable energy. ICE vehicles do not. There is no way that ICE can really win.

 

A hidden part of the energy chain for fossil fuels is that the crude oil takes a lot of energy (and produces a certain amount of pollution) on its way from the oil well to the garage forecourt- extraction, delivery, and refinement are not free. So any study must take account of the total cost of any fossil fuel, not just the emissions from the car itself.

 

Another complication is how much weight we attach to the location of emissions. It may be worse to burn fossil fuels in our cars in populated areas, rather than in power stations in rural areas. But it depends on what effects you are considering- the carbon is the same, but the particulates, NOx and other pollutants will be more harmful in a more populated place.

[SteamyTea]

It is the same fib that is said about PV and wind turbines.  Probably by the same people.

You have to do two calculations (or at least find two datasets).  The Well to Wheel emissions and the Manufacturing Embodied Energy.

There may be cases where, say a hyper car that is really used, has lower environmental life cycle costs compared to the the daily Tesla S, but that will also depend on where the vehicles are geographically based.

[Onoff]

6 hours ago, Crofter said:

ICE vehicles do not. There is no way that ICE can really win.

 

There's quite a bit of research into sustainable fuels with thoughts to gradually increasing blending proportions as engine technology progresses.....

 

My thoughts are that yes as early adopters EV users will reap some benefits, no different to the FiT rate farce. As take up peaks in favour of EVs then all the plus points like no congestion charge, no ULEZ issues, lower road tax will simply be phased out because of the potential loss of revenue to government. It's already happened in part with the subsidy cut on new EV's a couple of years back. Charging anywhere but at home off your own PV and you'll comparatively pay through the nose. Even then, if home charging peaks the price of PV will go up, road tax increase etc.

 

The masses won't / can't "win".

[Jeremy Harris]

A year or so ago I dug out the UK vehicle "well to wheel" CO₂ equivalent emissions figures:

 

Average for petrol engined vehicles = 178g CO2eq/km

Average for diesel engined vehicles = 145g CO2eq/km

Average for grid-powered electric vehicles = 90g CO2eq/km

 

[oldkettle]

7 hours ago, Triassic said:

 the cars appear far more complicated in their components and manufacture.

This is quite surprising. My understanding is the hardware of EVs is much simpler. 

I found this article https://www.wardsauto.com/ideaxchange/evs-not-easier-build-will-cut-jobs which funnily claims the total number of parts is roughly the same but what is seems to ignore is the number of moving parts. Much fewer of those in EVs. 

[Jeremy Harris]

EVs are a lot simpler mechanically, with no clutch, usually no gearbox (at least no changeable ratios usually) and none of the mechanical complexity of an internal combustion engine.  They do have complex battery management and motor control systems though, so in terms of parts count (at the component level) there are probably more parts in an EV than in a conventional car.

 

The reduction in mechanical moving parts has led to a reduction in servicing intervals. Two year servicing intervals are now fairly common, as there's nothing much to do on an EV other than check the brakes and tyres and perhaps change the battery/motor controller/motor coolant every few years.

[Crofter]

And the brakes themselves likely last longer because of regenerative braking.

[Jeremy Harris]

5 minutes ago, Crofter said:

And the brakes themselves likely last longer because of regenerative braking.

 

Very true.  I've owned three Prius cars, the last being a plug in, and none needed new brake pads.  I did ~65k miles in the first one, and the pads were around 60% warn when I traded it in.  The i3 I have now very rarely uses the friction brakes, and most of the time I drive without ever touching the brake pedal, as regen is strong enough to slow the car in normal traffic.

[SteamyTea]

I am still amazed that I have not had to change the brakes on my C-Max after driving 90,000 miles in it.  I do not know when they were changed prior to me owning it (bought it at 38,000 miles, so probably not changed).

Not sure if it is my driving style, or have brakes vastly improved.  Not as if it is a light car and I only drive on major A roads, it is all hilly lanes and towns down here.

[Big Neil]

How about total embodied carbon for production? Well to Wheel is certainly a compelling argument but i'm interested in the birthing cost.

[SteamyTea]

19 minutes ago, Big Neil said:

How about total embodied carbon for production?

Probably not that different.  Most of a vehicles mass will be steel for a normal car.  Some EVs are made of aluminium, which has a high initial embodied energy, but low when recycled.  I am not sure what the embodied energy of the batteries is, but probably not as high as people think.

As an example, Aluminium has a typical EE of 155 MJ/kg, when recycled it is 29 MJ/kg.

Steel is around 45 MJ/kg and 32 MJ/kg when recycled.

I have seen figures of between 350 to 650 MJ/kg for lithium ion batteries.

A litre of gasoline has about 45 kWh of energy in it (about 25% is usable for motion in a road car).  So taking worst case, a kilo of lithium batteries is the same as 4 litre of gasoline.

 

Edited April 30, 2019 by SteamyTea

[joe90]

 

Not wanting to divert this thread but I have always thought hydrogen powered cars were a good alternative.

 

 

[Jeremy Harris]

1 hour ago, Big Neil said:

How about total embodied carbon for production? Well to Wheel is certainly a compelling argument but i'm interested in the birthing cost.

 

Arguably my car has locked up a fair bit of carbon in its carbon fibre bodyshell/chassis...?

 

The downside is that carbon fibre has an EE of around 180 - 280 MJ/kg, so a lot higher than steel or aluminium, although being a lot less dense, and a lot stronger and stiffer, there's less of it for a given strength/stiffness requirement.

 

On a more serious note, as the car has very little metal in it (just the suspension, wheel, brake components, plus the drive train) it'd be interesting to see what the whole vehicle embodied energy is. 

 

One challenge with working out the total embodied energy is how to account for the R&D effort over the years.  Conventional cars have had well over a century of R&D effort, whereas electric cars have only had a couple of decades or so.

[Big Neil]

I'll take a peak at that hydrogen one later. I've sort of lost a bit of faith in them. Like 3D TV, promised to be great but just seem a bit pointless now. Why expend energy producing hydrogen to produce the energy, when you can just produce the energy in a sustainable manner and have a battery pack. I'd still have one i think because I like the idea of holding a handle and filling something up.

[Onoff]

9 minutes ago, Big Neil said:

I'll take a peak at that hydrogen one later. I've sort of lost a bit of faith in them. 

 

Keanu Reeves had it sussed! ?

[Big Neil]

what now - Keanu Reeves?

[Jeremy Harris]

Hydrogen, as an energy storage medium, is an interesting topic in itself.  The process of generating hydrogen is pretty simple and relatively non-toxic, but the efficiency is not great, either at the hydrogen generation end or the other end, converting hydrogen back into usable energy.

 

However, efficiency isn't everything, as if there is a surfeit of electricity generation in one area, and a demand for energy in another location, then it can make sense to use hydrogen as the storage medium.  A good example would be areas of Scotland and the distant isles, where there is often a surfeit of electricity generation from renewable sources (primarily wind and hydro).  Generating hydrogen from excess electricity generation, then transporting it for use as road fuel, may be a less polluting way of powering vehicles. 

 

However, using normal grid power to generate hydrogen doesn't seem to make sense, as the net CO₂eq would probably end up being much the same to using diesel or petrol for vehicle fuel.  As a fuel for use in urban areas, then it has some merit, but whether or not it makes more sense than using rapidly evolving BEV technology is debatable.  BEVs are now becoming mainstream, with practically every motor manufacturer (with the notable exception of the biggest, Toyota) either currently selling, or planning to sell, BEVs.

[joe90]

32 minutes ago, Big Neil said:

I'd still have one i think because I like the idea of holding a handle and filling something up.

 

Have you seen this 

 

[Big Neil]

oh god yes, hasn't everyone. I can't quite work out if it's a deliberate for the video though

[Onoff]

33 minutes ago, Big Neil said:

what now - Keanu Reeves?

 

https://m.imdb.com/title/tt0115857/

[daiking]

33 minutes ago, Onoff said:

 

https://m.imdb.com/title/tt0115857/

 

I preferred the Diana Ross version.

[SteamyTea]

Hydrogen is really a dead end for personal transport.  The energy density is just not that suitable for cars.  It is why car manufacturers opted for batteries and not hydrogen.

That is before all the other problems of using any liquid or gaseous fuels.

Then add in the mass and expense of a fuel cell to drive the motors, and that they have to run pretty hot to be efficient, it was really a non starter.

If it had been such a good idea, the current liquid fuel suppliers would have sorted it out and we would see hydrogen fuel everywhere, but we don't.

Then look at Iceland (the country, not the 2 quid a bag for kebab meat people).  They wanted to be the worlds first hydrogen economy, it failed spectacularly, though I think they have a small fishing fleet that may run on it.

One of the problems of EVs is that gasoline and diesel are just so good at storing energy, are easy to move and decant, and is incredibly cheap.

I like EVs, but I still want one that can do a reliable 400 miles between charges and can be bought on the second hand market for under £5000.

[SteamyTea]

5 hours ago, JSHarris said:

with the notable exception of the biggest, Toyota

I read something about this, and it did seem to make sense.

Apparently, Toyota worked out that with their battery supply capacity, making a large number of hybrids, instead of a smaller number of EVs, reduced the total overal emissions and energy usage.

Does make some sense as a stop gap.

 

[Conor]

Toyota are dragging their heels. The "self charging hybrid" BS add campaign sums up their attitude.