Author Topic: Here we go again  (Read 2960 times)

JimSh

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Re: Here we go again
« Reply #15 on: April 13, 2022, 04:55:50 PM »


Lorries are much harder to electrify as well, the 12 tonne + battery just detracts from the payload that can be carried,  a normal diesel powertrain is about 1200Kg and over 200 gallons of fuel about 1000kg, unlike a battery the fuel tank gets lighter as fuel is used. Range of diesel lorry can be easily over 1200 miles ( up to 2000 miles with twin 150 gallon tanks ), range of electric lorry 400 ? ( if there are no hills ). Time and current required to charge a 12 tonne battery  :o

Tesco is using 37 tonne DAF electric HGV with range of 100 miles using 350kw/h battery which weighs in at 700kg. 

https://www.commercialfleet.org/news/truck-news/2022/01/04/tesco-deploys-uk-s-first-electric-articulated-hgvs
Perhaps the future of road freight transport lies in hydrogen power (as long as the politicians don't try to persuade us to use hydrogen made from hydrocarbons)
https://www.fch.europa.eu/news/new-study-hydrogen-trucks-released

Or why not transfer much of the long distance freight to railways?
According to the Freight Network study 2017 (pdf)

"Rail freight produces 76% less carbon dioxide per tonne
of cargo relative to road haulage and each
freight train removes up to 76 lorries from the
roads
• Efficiency - on average, a gallon of fuel is able
to move a tonne of goods 246 miles on the
railway but only 88 miles by road"

embee

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Re: Here we go again
« Reply #16 on: April 13, 2022, 08:06:12 PM »

• Efficiency - on average, a gallon of fuel is able
to move a tonne of goods 246 miles on the
railway but only 88 miles by road"

Don't agree. That says a 44 tonne truck does 2mpg. Don't think so, not even if you are talking US gallons.
 OK so a 44 tonner only carries 30 tonnes of payload, so in truth at 8mpg that's actually only 240 tonne.mpg.

Efficiency in terms of tonne.mpg improves with scale, the bigger the transport the better. Trains are indeed good, cargo ships are even better if speeds are kept down.
« Last Edit: April 13, 2022, 08:13:42 PM by embee »

Jocko

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Re: Here we go again
« Reply #17 on: April 13, 2022, 09:32:20 PM »
I think if we had needed to get all our energy needs from wood that the planet would be a desert now, a bit like Mars, devoid of trees and also devoid of all the other stuff that makes human existance comfortable
That would not have been the case at all. Mankind would not have grown at the rate it did and the trees burnt would have been replaced by more trees. Life expectancy might only be 45 years for an elderly male farmer (less for a farm labourer) but the trees and the world would have continued relatively unscathed.

JimSh

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Re: Here we go again
« Reply #18 on: April 13, 2022, 10:57:15 PM »

• Efficiency - on average, a gallon of fuel is able
to move a tonne of goods 246 miles on the
railway but only 88 miles by road"

Don't agree. That says a 44 tonne truck does 2mpg. Don't think so, not even if you are talking US gallons.
 
No it doesn't.
You are assuming that  the mpg. is proportional to the mass of the vehicle which is not the case.

I don't know how they arrived at their figure because as you have correctly worked out if the lorry carries 30 Tonnes and does 8mpg that would be equivalent to each Tonne being carried 240 miles.
Perhaps it takes into account the fact that the lorry is not carrying a full load all the time.

embee

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Re: Here we go again
« Reply #19 on: April 13, 2022, 11:19:21 PM »
I'm not assuming anything.

The measure is simply the product of tonnes times miles divided by gallons (if those are the units chosen). They quote it as a distance for one tonne and one gallon, but the equation applies however you allocate it. They say 88 tonne.miles per gallon for road transport. I'd suggest for larger trucks it is a lot better than that.

JimSh

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Re: Here we go again
« Reply #20 on: April 14, 2022, 07:34:08 AM »
I'm not assuming anything.

The measure is simply the product of tonnes times miles divided by gallons (if those are the units chosen). They quote it as a distance for one tonne and one gallon, but the equation applies however you allocate it. They say 88 tonne.miles per gallon for road transport. I'd suggest for larger trucks it is a lot better than that.
But the force exerted by the load is downwards, ie at right angles to the direction of travel , not in the direction of travel.
The greater the load the greater will be the resistive forces on the lorry but they will not be in direct proportion.

Edit Apologies I found a reference to such a measure in an American link
https://www.imiproducts.com/blog/calculate-fuel-efficiency-gains/#:~:text=The%20best%20way%20to%20analyze%20trucking%20efficiency%20is,ton%20of%20freight%20per%20gallon%20of%20diesel%20fuel.

I presume a similar calculation can be applied here since it would be independent of units.
« Last Edit: April 14, 2022, 08:34:04 AM by JimSh »

embee

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Re: Here we go again
« Reply #21 on: April 14, 2022, 10:56:33 AM »
That's OK.

"Tonne miles per gallon" is just a generic measure for the fuel efficiency of moving a vehicle (or anything come to that) from A to B. Broadly speaking the bigger and heavier the better the tonne.miles/gallon. You can go into all the engineering and physics, drag vs rolling resistance etc, but it's largely irrelevant if all you want to do is compare different ways of moving stuff about.
If you start to break it down into payload and gross mass then it gets more involved, but the measure can still be used as a comparator. If you want to go to one end of a spectrum you can say that a single driver in a car going to the supermarket for a bottle of milk is about as bad as you get if you only consider the milk as the payload. The measure is usually applied with full payloads since this is the most efficient, and empty truck is fairly wasteful.
It's useful to compare bulk carrying of freight, big trucks are better than small trucks, trains are better still and ships about the best current bulk transportation. Planes aren't good, but they're quick.

It's just another "metric", useful for some purposes but not all. For domestic cars I used to estimate using 50 tonne.miles per gallon as a very simple rule of thumb, but that's a bit out of date, it's probably nearer 60 tmpg these days. It's been steadily improving over the years. Hybrids etc have changed things substantially (energy recovery systems and so on).
« Last Edit: April 14, 2022, 11:01:53 AM by embee »

culzean

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Re: Here we go again
« Reply #22 on: April 14, 2022, 12:14:14 PM »
I think if we had needed to get all our energy needs from wood that the planet would be a desert now, a bit like Mars, devoid of trees and also devoid of all the other stuff that makes human existance comfortable
That would not have been the case at all. Mankind would not have grown at the rate it did and the trees burnt would have been replaced by more trees. Life expectancy might only be 45 years for an elderly male farmer (less for a farm labourer) but the trees and the world would have continued relatively unscathed.

Have you seen what is left of the trees in most of Africa and South America ( and UK come to that matter, probably the country with less tree cover in Europe, maybe even the world ) ?  <10,000 years ago Egypt and North Africa used to be a fertile wooded area with lots of water,  the area is now called the Sahara Desert....  so unless global warming has been happening for about 10,000 years and people want to blame that as well, something else happened.  Brazil may be like the Sahara soon.... except for this - look at about 15 minutes where Haiti and Dominican Republic are mentioned,  Haiti uses renewables ( wood ) and has hardly any trees so it shows as brown ( semi-desert ) on satellite pictures, Dominican Republic on the other half of Island is green plenty of trees and uses fossil fuels.

« Last Edit: April 14, 2022, 12:37:50 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

culzean

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Re: Here we go again
« Reply #23 on: April 14, 2022, 12:45:39 PM »
Why renewables cannot save the planet...

Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

JimSh

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Re: Here we go again
« Reply #24 on: April 14, 2022, 12:53:13 PM »
Here we go again indeed.
Who keeps sending you this sh1t.
How can you get greener than the Amazon rain forest?
Of course excess carbon dioxide helps plants to grow up to a point
Sorry if this is a bit ad hominem but

https://www.wsws.org/en/articles/2021/11/25/ridl-n25.html

"But since his misadventure in banking, which cost British taxpayers 37 billion pounds and led to tens of thousands of foreclosures, the 5th Viscount Ridley was not content to retreat to his estate, home to the largest open-pit mine in Britain."

"Perhaps with similar sentiments, the Viscount returned to public life, elected by his aristocratic peers to the House of Lords in 2013, and has rebooted his career as a “science writer” to deny the existence of climate change, argue the genetic basis of race, and promote ideas associated with Social Darwinism."

culzean

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Re: Here we go again
« Reply #25 on: April 14, 2022, 01:00:36 PM »
Here we go again indeed.
Who keeps sending you this sh1t.
How can you get greener than the Amazon rain forest?
Of course excess carbon dioxide helps plants to grow up to a point
Sorry if this is a bit ad hominem but

https://www.wsws.org/en/articles/2021/11/25/ridl-n25.html

"But since his misadventure in banking, which cost British taxpayers 37 billion pounds and led to tens of thousands of foreclosures, the 5th Viscount Ridley was not content to retreat to his estate, home to the largest open-pit mine in Britain."

"Perhaps with similar sentiments, the Viscount returned to public life, elected by his aristocratic peers to the House of Lords in 2013, and has rebooted his career as a “science writer” to deny the existence of climate change, argue the genetic basis of race, and promote ideas associated with Social Darwinism."

So he is lying about the satellite images ? Lying about the Sahel ?
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

JimSh

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Re: Here we go again
« Reply #26 on: April 14, 2022, 02:47:40 PM »

So he is lying about the satellite images ? Lying about the Sahel ?
It is the result of land management practices and shows what can be done to mitigate the effects of climate change.

https://reliefweb.int/report/burkina-faso/regreening-sahel-quiet-agroecological-evolution

"Sahelian farmers, driven to desperation by the great droughts of the early 1970s and the 1980s, have ingeniously modified traditional agroforestry, water and soil management practices to restore the fertility of their land. In Niger, farmers have developed innovative ways to regenerate and multiply valuable trees whose roots already lay under their land. This ‘farmer-managed natural regeneration’ (FMNR) was first pioneered by outside actors but was spread rapidly by farmers once they observed its success. Changes to forestry laws and reforms of government structures that enable greater decentralization and local control of natural resources have also been significant enablers of change. "

https://www.bothends.org/en/Whats-new/Publicaties/Regreening-the-Sahel/

Edit added second link
« Last Edit: April 14, 2022, 02:50:16 PM by JimSh »

culzean

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Re: Here we go again
« Reply #27 on: April 14, 2022, 06:54:16 PM »
Oh, Land management is responsible, that would explain why even deep in rainforests and away from areas where humans manage the land,  vegetation is getting greener and growing faster...  Extra CO2 enables plants to use much less water to grow, which enables them to grow in areas with less water.... amazing stuff CO2, and perfectly natural.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

JimSh

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Re: Here we go again
« Reply #28 on: April 14, 2022, 07:52:14 PM »
Oh, Land management is responsible, that would explain why even deep in rainforests and away from areas where humans manage the land,  vegetation is getting greener and growing faster...  Extra CO2 enables plants to use much less water to grow, which enables them to grow in areas with less water.... amazing stuff CO2, and perfectly natural.
That's very interesting.
In order to grow plants need to combine carbon dioxide with water to form carbohydrates
6 CO2 + 6 H2O → C6H12O6 + 6 O
I can't see how extra carbon dioxide would enable this reaction to occur with less water if the equation is to remain balanced.   ::)

You cannae break the laws of stoichiometry Captain   :o    ::)

Edit applied subscripts and added Scotty type comment
« Last Edit: April 15, 2022, 02:03:25 PM by JimSh »

JimSh

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Re: Here we go again
« Reply #29 on: April 15, 2022, 11:48:46 AM »

• Efficiency - on average, a gallon of fuel is able
to move a tonne of goods 246 miles on the
railway but only 88 miles by road"

Don't agree. That says a 44 tonne truck does 2mpg. Don't think so, not even if you are talking US gallons.
 OK so a 44 tonner only carries 30 tonnes of payload, so in truth at 8mpg that's actually only 240 tonne.mpg.

Efficiency in terms of tonne.mpg improves with scale, the bigger the transport the better. Trains are indeed good, cargo ships are even better if speeds are kept down.
To Embee
Thanks for all the info on Tonne miles per gallon. I think I've just about got my head round the ramifications now.
I don't know why I'm going out of my way to defend a throwaway figure from a government paper or prolong an argument with someone who knows more about the subject than myself but the figure quoted is an average figure and you've used it to calculate a figure for an optimum situation. ( A 44tonne truck with a 30tonne payload ).
The 44tonne truck is not going to be always carrying 30tonnes so the tonne miles per gallon will be less.
(although the mpg will  be greater)
A lot of freight will be carried less efficiently in smaller vehicles.

I had never thought about the mpg of lorries before. It's frightening to think that they are only getting about 8mpg.
Although it should be obvious that they are going to be using a lot of fuel.

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