Electric Cars - Mark (Brazil)
Kind of a follow on from the pervious note (lpg).

Two questions really;

1) What's the state of progress and usability of electric cars these days ?

2) Are they really better than other fuels when you include generating the electricity, making the battery, disposing of old batteries etc. etc. ?

M.
Re: Electric Cars - Brian
I don't know about part 1 of your question

With regard to part 2, overall they produce more pollution, but move it away from the point of use to the power station, transmission lines, mines and disposal sites.
Re: Electric Cars - Andy
Hi

1)

The limiting factor of electric cars has always been the battery. Comparing the amount of energy per unit weight of a litre of petrol with a battery clearly shows how little energy a battery can store.

Another major problem is pattern of usage. People in general don't want to 'plug' cars in to recharge.

Two better contenders for 'green' travel are the fuel cell and the HEV (hybrid electric vehicle).

An HEV uses a super efficient engine (commonly using the Atkinson cycle rather than the Otto) with an electric motor to give 'boost' acceleration and total drive power during low speeds - i.e. crawling in traffic. This attempts to provide a good compromise. From a user point of view they treat it as a 'normal' car, the batteries being charged from the engine's 'spare' torque produced under light loads or during regenerative braking.

Fuel cell vehicles use hydrogen and are almost totally clean giving only water as an exhaust. The main problem is getting the hydrogen into the vehicle and keeping it cold.

2)

A common 'coal' fire power station is only 30% efficient. Modern gas turbine power stations are about 40%. The losses across the UK national grid are also worringly large (I think maybe 30% again). Losses across Russia are even worse (long story to do with the size of the country).

Therefore what you get at your house is a fraction of the energy initially used. Charging electric vehicles from a house is wasteful, but it does centralise the emissions at the power stations and (so its claimed) make it easier to clean up the emissions, rather than have millions of cars each 'mini' poluting.

However, just for perspective, a steam train is only about 2% efficient - so we have advanced a little!

Over next 5-10 years hybrids will become more common (e.g. toyota prius), following them it will probably be fuel cell vehicles. Electric vehicles may find a 'niche' such as the Ford Think vehicles being aimed firmly at cities.

Wrote more than I wanted to but hope it helps!

Andrew
Re: Electric Cars - Bill Doodson
Andy

I was'nt copying you but you sent your message whilst it was composing mine and trying to get the kid in bed. I am glad that our figures match up. What do you do for a living? I was a marine engineer (at sea) but am now the Chief Engineer of a BREWERY with the CCL and all of that.

Sorry HJ not cars but your know!


Bill
Re: Electric Cars - John Slaughter
Andy

You're on the right lines, but the figures are a bit pessimistic. Modern coal fired plants have an overall thermall efficiency of 35% or a little more, and CCGT's are more like 55%. Transmission loses are probably nearer another 5 percentage points.


Regards

John
Re: Electric Cars - Bill Doodson
Mark

Re 2,

I have to concur with Brian. Our older coal fired power stations have a thermal efficency of about 30-33% of the total energy in the coal, and produce large amounts of CO2. The newer Cogen gas stations have a T Eff of upto 40%, but then you have to take in the transmission losses of the Grid your charger etc. This means that only say 25% of the original PRIMARY energy ends up in the batteries of your car, then your car has losses. Electric cars charged at the mains will not save the planet they only move the pollution from the town center to Scandanavia (if the flue is as tall as the one at Drax) or more locally if shorter.

NUCLEAR power has none of these draw backs, but many others: PLEASE DISCUSS in no more than 2000 words.

Large marine diesel engines are the most fuel efficient on the KNOWN planet with efficiencies of well over 40%. Hitachi had an experimental engine over 10 years ago that they were claiming over 50% for, but it used CFCs in its heat recovery system. So in the end was probably more environmentaly unsound than an old London bus.

For an electric car to be NONE polluting the energy to power it MUST come from a none polluting source.

I think that the govenment should spend ALL of the money raised in FUEL duties on research into none polluting energy technology especially fusion. I wont mind a car or bike that is totally none polluting.

BUT it will still have to PERFORM.



Bill
Re: Electric Cars - steve paterson
Don't know about electric cars, or Lpg. I think that for various political reasons, (Manufacturing and Governmental), diesel engines will become the norm.
I've often wondered about water as a fuel. It's made up of Hydrogen and Oxygen, and it's easy to separate it into it's constituent elements using a single cell battery. You end up with one gas that burns, and one that helps it. Back in the 50's we forever reading about someone who had invented an engine that could run on water, but had been 'bought out' by the Petrol companies. Any truth in this ? Given that many recent engineering developments date back to the 1930's, could a water engine be in the pipeline?
Re: Electric Cars - Brian
Steve
The only practical way to separate water into hydrogen and oxygen at the moment is by electrolysis, i.e. passing a current through it. Which means large amounts of electricity are required from a non-polluting source.
At the moment that means hydro-electric or nuclear. Hydro-electric on land is only practical if you have a very high rainfall and mountainous country. Even Scotland, wet though it is, only has enough rain to produce about 15%, if I remember rightly, of its local power needs. Two large nuclear stations make up the other 85%.
I believe that the problem of nuclear waste disposal, which is the main worry of environmentalists (other than fantasies produced by reading too much cheap sci-fi in their youth) will be solved by sending it off to the sun where it will burn up harmlessly, becoming a minute fraction of the sun's fuel.
However, in the meantime tidal power is our best bet, but that means the loss of some estuary space and some inland areas for pumped storage schemes to store energy between the production (dependent on the tide schedules) and the demand (dependent on the time of day/day of the week/time of year).
The Severn estuary is the best location in the UK, having a large tidal range, with pumped storage in Wales.
For examples see the Dutch barrage, the French one near St Malo, and the pumped storage scheme which has been operating in Wales for about 20 years, utilising 2 reservoirs with a power station buried in tunnels in the mountain.
Re: Electric Cars - Chris
Brian wrote:

> I believe that the problem of nuclear waste disposal, which
> is the main worry of environmentalists (other than fantasies
> produced by reading too much cheap sci-fi in their youth)
> will be solved by sending it off to the sun where it will
> burn up harmlessly, becoming a minute fraction of the sun's
> fuel.

Er, remember Challenger? How do you fancy thirty tonnes of high level nuclear waste descending on you from the upper atmosphere? Not in my lifetime mate.

Biomass power stations and/or biodiesel-electric cars would be a better answer. The technology already exists. All we need is the will.

Chris
Re: Electric Cars - Vin
Losses over the National Grid in 1995 were 3%.
Re: Electric Cars - Stuart B
What do people reckon about biomass fuelled power stations?

Properly run they are C02 neutral, and with the increasing use of sophisticated corrosion resistant materials, (just happen to have a few in stock my boy) you can increase thermal efficiency by upping the operating steam pressure on the newer plants being built in Scandinavia, (sorry to be a Swedish Andy Bairstow)
Re: Electric Cars - Jonathan Shaw
On the contray I think electric cars do make sense for many people see my
web page on the subject www.ev.shawcan.com/
The effieciencies of marine diesels are not to be confused with car diesels
as the former operate at near constant speed where as the later need to
provide power from 1-4.5k rpm. Also lots and lots of pollution caused in
cars when warming up, so if you are on a short journey although overall
efficiency of the EV may be low its still cleaner and not polluting in areas
of population.

HEVs can be parallel (electric motor assisting) like the Prius and Insight
or series where the generator provides current to drive a motor which alone drive the wheels- like a diesel-electric train. I would have thought series
better for HEV use as the internal combustion engine could be optimised to run at constant speed. Also I'm puzzled why the 2 available HEVs are petrol based and not diesel.

As for total power efficency from powerstation to EV check out this document www.lynchmotor.com/PDF files/241.401.pdf. There are loads of other interesting articles on the site www.lynchmotor.com/240.htm is EVs are your thing. There is also the Battery Vehicle Society www.bvs.org.uk/ for people who are really interested in EVs
Re: Electric Cars - Jonathan Shaw
Andy
I have t confess I didn't realise that there was such a thing as a 5 cycle/stroke engine! Nor Series and Parallel hybrids - will have to do more surfing to lean more.

Not sure why a hybrid has to switch off frequently even with a small battery pack? Or why it shgould be a problem for deisel. is it because the diesel gets cold and so need a glow plug style start?

Thanks
Jon
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Re: Electric Cars - Andy
Hi Jonathan

The toyota prius is not a series or parallel hybrid but both!

Advances in transaxle design now mean that a hybrid can work either in series or parallel, or a 'mix' of both.

The 1.5 prius engine is a 'detuned' engine which is not particularly powerful but gives good efficiency. Both the Insight and Prius use the 5 cycle Atkinson engine which has different compression and expansion volumes. This allows for a much greater efficiency at the cost of low end torque. The low end torque is provided by a traction motor in parallel with the engine.

A hybrid turns off/on the engine frequently, having a diesel would sap more power with the start up/shutdown.

Andrew
Re: Electric Cars - Brian
Chris
I agree that Sun disposal is probably not on at the moment, but I would expect it to be so in a couple of decades when horizontal take-off space vehicles are developed.
The other advantage, even with present technology, is that small, harmless loads can be launched, stored in orbit accumulated for a single, larger, Sun shot.
 

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