End of EV Subsidies?

[DA? + 301]

6 hours ago, Bobby P said:

Just to piss people like you off. LOL!

I take it your reply is to the last question as you just wrote some FUD you read based on nothing. Well if it makes you happy to drive an ICE, it's like those smokers that like to purposely smoke around people, just to show they can. Makes me pity them really if that's all they have.

[jaycee + 348]

9 hours ago, NickW said:

3. You have omitted the fact that electric motors are inherently more efficient than ICE engines. 1 KWH of electricity  will propel a Nissan Leaf 5 km so thats 720KJ / Km. A Nissan Tilda doing 7.1L/100KM (40mpg) uses 2.48 MJ per km. Even your coal plant running at 35% thermal efficiency will be around the 2 MJ / km mark. A

As an engineer I cannot let that stand it’s like the tax issue you are not looking at it correctly. The efficiencies of an electric car does not take into account how much energy is wasted getting to the car from the power generator or the fact charging a car involves losses as well, you are missing those out when you quote the efficiency of an EV engine. The power in a car is generated in the car so other losses need to be taken into account for EVs another trick by that industry to hide facts.

By the way you miss the point about gas turbines powering EVs. I was pointing out that you are burning hydrocarbons to power EVs my suggestion you use the waste heat was me trying to point out it was not feasible to be green that way. You are not getting my sense of humour as is obvious from many of your replies.

Right that’s it bye

Edited December 7, 2018 by jaycee

[Auson + 123]

2 hours ago, jaycee said:

As an engineer I cannot let that stand it’s like the tax issue you are not looking at it correctly. The efficiencies of an electric car does not take into account how much energy is wasted getting to the car from the power generator or the fact charging a car involves losses as well, you are missing those out when you quote the efficiency of an EV engine. The power in a car is generated in the car so other losses need to be taken into account for EVs another trick by that industry to hide facts.

By the way you miss the point about gas turbines powering EVs. I was pointing out that you are burning hydrocarbons to power EVs my suggestion you use the waste heat was me trying to point out it was not feasible to be green that way. You are not getting my sense of humour as is obvious from many of your replies.

Right that’s it bye

jaycee,

Your spot on its statistics lies and statistics. A diesel electric train exploits this electric motor efficiency by being its own power plant burning diesel. Or the London buses which have been running mostly on the Diesel generator due to problems with the batteries.  

https://www.theguardian.com/politics/2015/jul/20/flat-batteries-london-buses-add-to-boris-johnsons-problems

Edited December 7, 2018 by Auson

[DA? + 301]

1 hour ago, Auson said:

jaycee,

Your spot on its statistics lies and statistics. A diesel electric train exploits this electric motor efficiency by being its own power plant burning diesel. Or the London buses which have been running mostly on the Diesel generator due to problems with the batteries.  

https://www.theguardian.com/politics/2015/jul/20/flat-batteries-london-buses-add-to-boris-johnsons-problems

That article is so old the link has dust on it.

[Auson + 123]

1 hour ago, DA? said:

That article is so old the link has dust on it.

and guess what the problem still isn't fixed I see and hear them running on the engine as a generator all the time !

[DA? + 301]

27 minutes ago, Auson said:

and guess what the problem still isn't fixed I see and hear them running on the engine as a generator all the time !

Are they I thought the batteries were replaced ages ago. When is that old fleet of Boris buses been retired, heard it was a cockup from the beginning.

[NickW + 2,714]

6 hours ago, jaycee said:

As an engineer I cannot let that stand it’s like the tax issue you are not looking at it correctly. The efficiencies of an electric car does not take into account how much energy is wasted getting to the car from the power generator or the fact charging a car involves losses as well, you are missing those out when you quote the efficiency of an EV engine. The power in a car is generated in the car so other losses need to be taken into account for EVs another trick by that industry to hide facts.

By the way you miss the point about gas turbines powering EVs. I was pointing out that you are burning hydrocarbons to power EVs my suggestion you use the waste heat was me trying to point out it was not feasible to be green that way. You are not getting my sense of humour as is obvious from many of your replies.

Right that’s it bye

I have acknowledged transmission losses. To take it further from what I recall its approx 3% per 100km on AC and 1-1.5% on DC. Charging efficiencies on decent Lithium on a slow - medium charge are >80%.

So that quantifies your transmission losses. Now given the fact that electrical generation in the UK is becoming more distributed.  transmission distances are effectively falling and therefore transmission losses are too. What are we looking at 25% inc battery charge efficiency.

https://en.wikipedia.org/wiki/Electric_power_transmission#Losses

Generating plant distribution (which doesn't include wind, solar, WTE & Biomass)

https://www.powerplantmaps.com/UK.html#.XAqCgf5LHL8

Just to balance this argument 

 how much energy is lost at the  refinery and then by tanker to the petrol station? There are lots of VOC emissions from spillages, evaporation, and displacement of vapours when tanks are filled- that's why it is tightly regulated -at least at the petrol station and storage depot.

RE: GGCT

Yes these are thermal plant but unlike a petrol engine they will run at efficiencies of 50-60% and are extremely clean in comparison. If you can utilise the waste heat then that thermal efficiency is up to 85-90%.

Some of the gas now used is biogas. By 2050 the UK will be generating approx. 150TWH of biogas from waste organic material. At 55% thermal efficiency that's enough to run 9-10 GW of CCGT 24/7.

https://bioenergyinternational.com/markets-finance/uk-green-gas-certificate-demand-smashes-1-twh-barrier

In response to your comment - highlighted in bold;

Don't give up the day job

 

[Dan Warnick + 6,100]

1 hour ago, DA? said:

Are they I thought the batteries were replaced ages ago. When is that old fleet of Boris buses been retired, heard it was a cockup from the beginning.

And therein lay the comments from @jaycee about all good plans....

[NickW + 2,714]

1 minute ago, Dan Warnick said:

And therein lay the comments from @jaycee about all good plans....

Politics was the driver in that one before engineering considerations.

A sane transport policy in London would have been to convert the fleet over to CNG with a longer term view to using CNG hybrids.

[Dan Warnick + 6,100]

19 minutes ago, NickW said:

Politics was the driver in that one before engineering considerations.

A sane transport policy in London would have been to convert the fleet over to CNG with a longer term view to using CNG hybrids.

Yes, but what makes you think politics will not play a role on this issue?

[Auson + 123]

11 minutes ago, NickW said:

Politics was the driver in that one before engineering considerations.

A sane transport policy in London would have been to convert the fleet over to CNG with a longer term view to using CNG hybrids.

Nick W,

Yes politics designed and built those £350,000  buses. Damn you Boris with your crappy designs. I bet the batteries were at least £50k a pop probably need some new ones in another 2 or 3 years.

TFL is also loss making so transport is subsidised.

[DA? + 301]

28 minutes ago, Auson said:

Nick W,

Yes politics designed and built those £350,000  buses. Damn you Boris with your crappy designs. I bet the batteries were at least £50k a pop probably need some new ones in another 2 or 3 years.

TFL is also loss making so transport is subsidised.

Going over to all electric buses now it seems.

[NickW + 2,714]

1 hour ago, Auson said:

Nick W,

Yes politics designed and built those £350,000  buses. Damn you Boris with your crappy designs. I bet the batteries were at least £50k a pop probably need some new ones in another 2 or 3 years.

TFL is also loss making so transport is subsidised.

Hardly unique - I think if you take a look across the globe most public transport network systems are subsidised to some degree because governments deem them to have certain benefits to society beyond the profit / loss account.

[NickW + 2,714]

53 minutes ago, DA? said:

Going over to all electric buses now it seems.

Makes more sense. EV is less complicated than hybrid and the nature of the bus runs is that the bus can undergo several short burst charges as they arrive at terminals if necessary. Mind you given London road speeds I suspect they can last all day on one battery charge 

[jaycee + 348]

1 hour ago, NickW said:

I have acknowledged transmission losses. To take it further from what I recall its approx 3% per 100km on AC and 1-1.5% on DC. Charging efficiencies on decent Lithium on a slow - medium charge are >80%.

So we are looking at minimum 3% transmission losses plus you say 20% charging losses I would say more but hey ho we are still over 20% losses to add to the inefficiency of the power generator, you suggested a coal plant which is 33 to 40% which is about the same efficiency as a petrol car so EVs are over 20% worse efficiency wise but EV builders tell you how efficient the engine is compared to a petrol one, really!?

I wont add in the cost/losses of transporting petrol unless you want to add in the cost of transporting coal to the power station.

Please dont become an engineer you keep missing important points but so do all renewables and EV advocates asait does not suit the narrative.

Renewable and EVs will eventually become viable and worth while doing but they are not just now and those that tell you otherwise are only doing it to make money. Try to think more about it. You need a smart grid and install millions of charging points, you need loads more renewables, ones that generate reliably at night so forget solar and wind is intermittent unless you build 4 times the installed capacity to get the power output on the nameplates, you need to find a way to raise all the taxes lost on petrol and NS oil then you have to realize that EVs are not as efficient as the industry says. Lots and lots of costs to a country that is about to go into recession with Brexit and is still in a worse state than pre banking crisis. Wrong time to bring in a expensive change that does not benefit the UK plenty more ways to spend money effectively.

 

2 hours ago, NickW said:

Yes these are thermal plant but unlike a petrol engine they will run at efficiencies of 50-60% and are extremely clean in comparison. If you can utilise the waste heat then that thermal efficiency is up to 85-90%.

You are still missing the point  I am making, deliberately I must now assume, its GAS!!! you are burning its a hydrocarbon the whole point of the EV manufacturers crowing how green they are is that they run on electricity from renewables. You are now changing the subject though to compare the gas turbine to a petrol engine when you started out using a coal fired power station as the comparison clearly you don't like the numbers for that comparison. If you want to add in gas turbines please subtract the transmission and charging losses for the EV circa 23%, plus, and the numbers are not so different.

Getting very tired of answering people who don't stick to the facts or decide to answer points I have not made hence my decision to quit this thread but if you are going to insult my day job then I am going to reply. Hopefully we can let it rest at that.

[SERWIN + 749]

Don't need data on this one, I have driven the trucks and they will try to stop themselves if something pulls right in front of them, and not too long ago a Tesla drove right into the back of a stopped fire truck. What data are you referring to do I need now besides first hand experience?

[DA? + 301]

2 hours ago, jaycee said:

So we are looking at minimum 3% transmission losses

Actually with HVDC it's more like 0.3% and UHVDC it's even less. China's moving electricity from the west of the country to the east.

 

2 hours ago, jaycee said:

Getting very tired of answering people who don't stick to the facts

That's funny coming from you.

2 hours ago, jaycee said:

but if you are going to insult my day job

I hope it's not as an electrical engineer.

[DA? + 301]

2 hours ago, SERWIN said:

Don't need data on this one, I have driven the trucks and they will try to stop themselves if something pulls right in front of them, and not too long ago a Tesla drove right into the back of a stopped fire truck. What data are you referring to do I need now besides first hand experience?

Seems you need to look at the data as you don't understand whats changing. Personal experience is full of bias and the full picture needs to be seen. I don't think you have a clue what Tesla is doing, you just like listening to the FUD as this reinforces your misinformed opinion.

[NickW + 2,714]

5 hours ago, jaycee said:

So we are looking at minimum 3% transmission losses plus you say 20% charging losses I would say more but hey ho we are still over 20% losses to add to the inefficiency of the power generator, you suggested a coal plant which is 33 to 40% which is about the same efficiency as a petrol car so EVs are over 20% worse efficiency wise but EV builders tell you how efficient the engine is compared to a petrol one, really!?

I wont add in the cost/losses of transporting petrol unless you want to add in the cost of transporting coal to the power station.

Please dont become an engineer you keep missing important points but so do all renewables and EV advocates asait does not suit the narrative. Yeah yeah - heard it all before😂

Renewable and EVs will eventually become viable and worth while doing but they are not just now and those that tell you otherwise are only doing it to make money. Try to think more about it. You need a smart grid and install millions of charging points, you need loads more renewables, ones that generate reliably at night so forget solar and wind (1) is intermittent unless you build 4 times the installed capacity to get the power output on the nameplates, you need to find a way to raise all the taxes lost on petrol (2) and NS oil then you have to realize that EVs are not as efficient (3) as the industry says. Lots and lots of costs to a country that is about to go into recession with Brexit and is still in a worse state than pre banking crisis. Wrong time to bring in a expensive change that does not benefit the UK plenty more ways to spend money effectively.

 

You are still missing the point  I am making, deliberately I must now assume, its GAS!!! (4)  you are burning its a hydrocarbon the whole point of the EV manufacturers crowing how green they are is that they run on electricity from renewables. You are now changing the subject though to compare the gas turbine to a petrol engine when you started out using a coal fired power station as the comparison clearly you don't like the numbers for that comparison. If you want to add in gas turbines please subtract the transmission and charging losses for the EV circa 23%, plus, and the numbers are not so different.(5)

Getting very tired of answering people who don't stick to the facts or decide to answer points I have not made hence my decision to quit this thread but if you are going to insult my day job then I am going to reply. Hopefully we can let it rest at that.

Just think - if we never strove to achieve new things there would be no need for Engineers!

1. Nope - capacity factors on modern offshore wind are >40%

2. Governments simply tax something else to meet PSSR.  I have repeatedly explained that alternative taxation systems on personal transport can include a charge per mile. You repeatedly ignore this point. We are back to the if people give up smoking where will the tax come from nonsense🤦‍♀️

3. I didn't actually start the ICE v EV efficiency debate. The main direct benefit of EV's is the elimination of tail pipe emissions in close proximity to people which has significant health implications. Again you repeatedly ignore this. 

4. From a green perspective, yes the best options are renewables. In the absence of renewables being able to meet demands and putting aside the nuclear option, gas burnt in modern CCGT are the cleanest conventional FF option. 

5. I will take the bait. 

Gas burned in a a CCGT at 55% efficiency = 6.55 MJ of primary energy per kw of electricity

Transmission and charge losses 23% so input of primary energy increases to 8.1MJ to produce that 1 KWH of E

8.1 MJ / 5(KM) = 1.62MJ /KM

-------------------------

Petrol car doing 40mpg or 7.1 l/ 100KM

7.1 litres of petrol = 248.5MJ / 100KM = 2.485 MJ / KM

So EV charged from a modern CCGT uses 35% less energy than the equivalent for petrol. Furthermore I haven't accounted for any losses on the petrol system from evaporation, leakage, or loss of vapours when filling tanks so that gap would be a little wider in reality. 

 

[jaycee + 348]

19 hours ago, NickW said:

Just think - if we never strove to achieve new things there would be no need for Engineers!

Just think if we thought about things before we did it that’s what you need engineers for. Headlong rush into the unknown when you are dependent of the power to run a country is rather silly. Germany, as I have pointed out did this and have landed up getting it totally wrong and had to build coal plants, some provinces in Canada are having similar issues with a headlong rush to go Green. Engineers have a habit of pointing out flaws which others dismiss to their detriment. 

19 hours ago, NickW said:

1. Nope - capacity factors on modern offshore wind are >40%

Nope onshore is 25%

19 hours ago, NickW said:

2. Governments simply tax something else to meet PSSR.  I have repeatedly explained that alternative taxation systems on personal transport can include a charge per mile. You repeatedly ignore this point. We are back to the if people give up smoking where will the tax come from nonsense🤦‍♀️

So the motorist will have to pay the same in tax at a future date than he does just now, which was my point, read back, there is no cost saving in going to EVs as the vast majority of the cost of running a car is taxes which EVs largely miss right now as electricity has 5% VAT.

I do not ignore your point regards taxing per mile but it is irrelevant how your extract the extra cash but it will have to come out, Joe Bloggs will pay the same to drive to work whether its in petrol taxes or per mile taxes.

With a smoking ban others will have to pay the taxes simple.

19 hours ago, NickW said:

3. I didn't actually start the ICE v EV efficiency debate. The main direct benefit of EV's is the elimination of tail pipe emissions in close proximity to people which has significant health implications. Again you repeatedly ignore this. 

Yep I did it appears you are the only EV supporter I have met who does not think EVs are the best way to eliminate CO2 emissions. Very odd.

19 hours ago, NickW said:

4. From a green perspective, yes the best options are renewables. In the absence of renewables being able to meet demands and putting aside the nuclear option, gas burnt in modern CCGT are the cleanest conventional FF option. 

Why ignore nukes that is the logical answer. Burning hydrocarbons is burning hydrocarbons, check out the calc at the end for which way of burning hydrocarbons is most efficient you may get a surprise.

19 hours ago, NickW said:

5. I will take the bait. 

Gas burned in a a CCGT at 55% efficiency = 6.55 MJ of primary energy per kw of electricity

Transmission and charge losses 23% so input of primary energy increases to 8.1MJ to produce that 1 KWH of E

8.1 MJ / 5(KM) = 1.62MJ /KM

-------------------------

Petrol car doing 40mpg or 7.1 l/ 100KM

7.1 litres of petrol = 248.5MJ / 100KM = 2.485 MJ / KM

So EV charged from a modern CCGT uses 35% less energy than the equivalent for petrol. Furthermore I haven't accounted for any losses on the petrol system from evaporation, leakage, or loss of vapours when filling tanks so that gap would be a little wider in reality. 

 

I dispute your calculation. Don’t know where you get your EV figures from but I have given links to the petrol one and corrected your calc for EVs.

EV

Basic calc for the EV is wrong

To get 6.55MJ out your will need to put in 8.97 MJ not 8.1MJ

So EV is 8.97MJ/5km= 1.79 MJ/Km

Petrol

mpg Peugeot 108 is 69 mpg, of 58 city and 79 highway, which equals 24.42 km/L

1L of Petrol has 32 Mj

So 24.42 km uses 32Mj which equals 1.31MJj/km

Result is a petrol engine uses 27 % less energy than an EV.

I have not taken into account loss of gas in transportation to power station, best guess number I could find was 4%, and the losses filling a petrol tank 1 to 2%

Link to energy per litre petrol half way down page

http://science.answers.com/Q/How_many_joules_are_in_a_litre_of_petrol

Link to mpg Peugeot 108

https://www.google.co.uk/search?q=peugeot+108+mpg&oq=Peugeot+108+mpg&aqs=chrome.0.0l6.2714j0j7&sourceid=chrome&ie=UTF-8

[jaycee + 348]

22 hours ago, DA? said:

Actually with HVDC it's more like 0.3% and UHVDC it's even less. China's moving electricity from the west of the country to the east.

That's funny coming from you.

I hope it's not as an electrical engineer.

We have an AC system in the UK last I looked costs money to change out system

You make me laugh all the time.

Told you before I am C&I, you should know what that means having worked in a power plant, with a degree in Electrical and Electronic

 

[NickW + 2,714]

1 hour ago, jaycee said:

Just think if we thought about things before we did it that’s what you need engineers for. Headlong rush into the unknown when you are dependent of the power to run a country is rather silly. Germany, as I have pointed out did this and have landed up getting it totally wrong and had to build coal plants, some provinces in Canada are having similar issues with a headlong rush to go Green. Engineers have a habit of pointing out flaws which others dismiss to their detriment. 

Nope onshore is 25% (1) 

So the motorist will have to pay the same in tax at a future date than he does just now, which was my point, read back, there is no cost saving in going to EVs as the vast majority of the cost of running a car is taxes which EVs largely miss right now as electricity has 5% VAT. (2) 

I do not ignore your point regards taxing per mile but it is irrelevant how your extract the extra cash but it will have to come out, Joe Bloggs will pay the same to drive to work whether its in petrol taxes or per mile taxes (3) 

With a smoking ban others will have to pay the taxes simple (4) 

Yep I did it appears you are the only EV supporter I have met who does not think EVs are the best way to eliminate CO2 emissions. Very odd. (5)

Why ignore nukes that is the logical answer. Burning hydrocarbons is burning hydrocarbons, check out the calc at the end for which way of burning hydrocarbons is most efficient you may get a surprise (6)

I dispute your calculation. Don’t know where you get your EV figures from but I have given links to the petrol one and corrected your calc for EVs.

EV

Basic calc for the EV is wrong

To get 6.55MJ out your will need to put in 8.97 MJ not 8.1MJ

So EV is 8.97MJ/5km= 1.79 MJ/Km

Petrol

mpg Peugeot 108 is 69 mpg, of 58 city and 79 highway, which equals 24.42 km/L

1L of Petrol has 32 Mj

So 24.42 km uses 32Mj which equals 1.31MJj/km

Result is a petrol engine uses 27 % less energy than an EV.

I have not taken into account loss of gas in transportation to power station, best guess number I could find was 4%, and the losses filling a petrol tank 1 to 2%

Link to energy per litre petrol half way down page

http://science.answers.com/Q/How_many_joules_are_in_a_litre_of_petrol

Link to mpg Peugeot 108

https://www.google.co.uk/search?q=peugeot+108+mpg&oq=Peugeot+108+mpg&aqs=chrome.0.0l6.2714j0j7&sourceid=chrome&ie=UTF-8

 My wife is a Chartered Chemical Engineer. You don't sound like an Engineer to me. 

1. Yes - for onshore. However I said Offshore where the majority of the UK's future growth in wind power will come from.  Try reading what I wrote. BTW - capacity factors for onshore are rising as small 1990's turbines (200-500KW) are gradually replaced with 2-4 MW turbines which are much taller. 

2. I have never argued that there is parity in taxation per mile between EV's and ICE. I have said repeatedly - the Govt justification for the EV preference is to increase EV market share. 

3. I have never argued that the EV driver should pay no tax. This is another member of your strawman army. 

4. I made no reference to a 'smoking ban' but yes if people stop smoking the tax revenue will be raised from another source. 

5. I don't know which dark orifice you have pulled this one out of but my view is that EV's offer a moderate improvement in terms of CO2 emissions but the primary immediate benefit is a stark reduction in tailpipe emissions of pollutants that are harmful to health. 

6. I took nucs out of the equation as they are an unlikely source of additional generating capacity in the short - medium term. I referenced CCGT because any additional conventional thermal capacity will most likely be CCGT.

7. I see you are comparing apples and oranges.  

The leaf is a small family car

https://en.wikipedia.org/wiki/Nissan_Leaf

The 108 is a city car

https://en.wikipedia.org/wiki/Peugeot_108

The leaf is almost a metre longer than the 108. My comparison was with a Nissan Pulsar which has a similar wheelbase as the Leaf. 

https://www.honestjohn.co.uk/realmpg/nissan/pulsar-2014

 

69mpg for a 108 😄

Low 50's in the real world. 

https://www.honestjohn.co.uk/realmpg/peugeot/108-2014

If you want to stick with Peugeot a fairer comparison would be against a 308 although it is smaller than the Leaf. 

--------------------------

A recalc of the EV figures. 

To get 1 KWH into the battery you need to input 4.675 MJ

4.675 / 0.55 (efficiency of CCGT)  = 8.5 MJ of primary energy input at the CCGT

So the figure is 1.7 MJ / Km 

[jaycee + 348]

1 hour ago, NickW said:

My wife is a Chartered Chemical Engineer. You don't sound like an Engineer to me. 

Lost  for words that’s the most absurd statement you have made so far and you have had a few.

I will respond to your other replies when I have time maybe Monday, weekends involve a lot off sport for me. One question I used the manufacturers quoted figures for the 108 where did you get the Leaf’s?

[NickW + 2,714]

8 minutes ago, jaycee said:

Lost  for words that’s the most absurd statement you have made so far and you have had a few.

I will respond to your other replies when I have time maybe Monday, weekends involve a lot off sport for me. One question I used the manufacturers quoted figures for the 108 where did you get the Leaf’s?

You seem to mention in every other sentence you are an Engineer......and then you come out with the 'piece da resistance' highlighted above. 

I will let you in on a little secret - the manufacturers fuel consumption figures are utter bullshit. They are based on laboratory rolling road tests where the vehicle is kept at an optimum temperature before performing that test. Now manufacturers figures are useful to compare models but do not reflect real world conditions. 

Furthermore the 108 is a glorified golf buggy whereas the  Leaf is functional as a small family car  - its almost a metre longer and actually has a boot you can put stuff in. Additionally the Leaf has much better performance in terms of acceleration. 

There are numerous independent real life tests of the Leaf. 80 miles is typical for a 24kwh model (as opposed to the manufacturers 124 mile range) . Even at 80 miles thats 5.36km/ kwh

https://www.nimblefins.co.uk/nissan-leaf-battery-capacity-range

[ronwagn + 6,290]

On 12/7/2018 at 1:25 AM, Auson said:

jaycee,

Your spot on its statistics lies and statistics. A diesel electric train exploits this electric motor efficiency by being its own power plant burning diesel. Or the London buses which have been running mostly on the Diesel generator due to problems with the batteries.  

https://www.theguardian.com/politics/2015/jul/20/flat-batteries-london-buses-add-to-boris-johnsons-problems

Compressed Natural Gas Buses are all they use in Los Angeles, California. They have been using them for a long time now. London should be using them instead. IMHO all smog plagued cities should be using natural gas vehicles as soon as possible.