Toll roads are ubiquitous!
Not only are they becoming the default type of road system, but I foresee a time when governments start building them between cities as well.
Toll roads are usually built by companies at the behest of governments (usually State) to supply a badly needed missing transit corridor between two parts of a city, or to alleviate traffic congestion in one part of an overcrowded cit.
State governments love them because they can claim to be doing something about the problem (relieving congestion and improving traffic flow) and it doesn't cost them a cent. The company puts up its own money, designs and then builds the road and, in return, gets the right to charge a toll on cars using it for the next twenty or thirty years.
The problem with Toll Roads is that they are not the solution to the problem of traffic congestion. They are in fact the solution to a completely different problem, namely, how do you funnel groups of people from different ares into one single location where you can gouge money out of them.
The requirements of this second solution is to restrict where people can get on or off until such time as you have managed to collect the toll off them. More than one collection point costs money, so cars are funnelled along a channel of roads unable to get on or off where they'd like.
The same thing applies when you replace toll booths with E-Tags. They cost as much money as a set of boom gates, so you only want the minimum set required. This means you still restrict where people can get on or off the toll road until they have passed the collection point.
The net effect is you replace a public road with a congestion problem that has lots of entry and exist points with a privately owned road that you have to pay to use and has very very few exit points (none of them near where you want to exit).
Monday, September 29, 2008
Wednesday, September 10, 2008
Ethanol as fuel is a great con!
It has been marketed as environmentally positive when added to petrol because it reduces harmful emission.
This may be true, but it also reduces the efficiency of the petrol in your car. If you add 10% ethanol to your petrol, you will find that your car travels 10% less kilometres on a given tank of fuel. Result: you have to buy more fuel to cover the same number of kilometres you previously travelled on petrol-only fuel.
How can this be? Well, it comes down to knowing the difference between the octane level of a fuel and its energy density.
The Research Octane Number (RON), or octane level, of a fuel is a measure of how easily it burns, while the energy density is a measure of how much work you can get it to do. I will spell this all out at the bottom of the article for those who want to know.
So, you add some ethanol to your petrol and your motor will happily burn it, just as though it was petrol. However, it won't do as much work as petrol, so you will cover less kilometres on a tank of this fuel mix than you would on petrol alone. In effect, you are being sold "watered-down" petrol; a bit like buying a litre of milk that has been thinned with water.
Lets not even consider that it takes nearly 200 kg of corn to create about 90 litres of ethanol (That same amount of corn could supply enough calories to feed a person for a year); or that the demand for bio fuels will drive the price of corn beyond the ability of people, who need it for food, to buy it. (1)
The simple fact is, if you "water-down" the fuel, we have to use more fuel to do the same work.
To sum up,(as you can see from the definitions below) Ethanol will burn as easily as petrol, even in high performance cars (where it probably burns better), but it will do less work than petrol. This means you will drive less kilometres on a tank of ethanol-mixed fuel as you would on a petrol-only fuel. The more ethanol in the mix, the less kilometres you get.
=================================================================
Definition of octane rating
The octane rating of a spark ignition engine fuel is the detonation resistance compared to a test mixture of iso-octane (with an octane rating of 100) and n-heptane (with an octane rating of zero).
The octane rating does not give you the energy content of the fuel, but only describes its tendency to burn rather than explode.
The octane rating used by most countries, including Australia, is the Research Octane Number (RON). In Australia it is the "headline" octane rating, shown on the pump. In America, their "headline" octane rating for a fuel is lower because it is calculated differently.
The RON of a fuel is determined by running it in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane. (2)
It is possible for a fuel to have a RON greater than 100, because iso-octane is not the most knock-resistant substance available. Alcohol fuels such as ethanol or methanol can have significantly higher octane ratings; ethanol's RON is 129
Ethanol has a Research Octane Number (RON) of 129
Regular Gasoline has a RON of a minimum of 91
Premium Gasoline has a RON of a minimum of 95
Definition of Energy Density
The Energy density of a fuel is the amount of energy stored in a given volume.
Energy per unit volume has the same physical units as pressure, that is Joules/Litre, or megajoules per litre (MJ/L) in the case of fuel.
If we were talking about food, the energy density would be measured in calories. (3)
The energy density for Ethanol, by mass is 30 MJ/kg, by volume is 24 MJ/L
The energy density for Gasoline, by mass is 46.9 MJ/kg, by volume is 34.9 MJ/L
The energy density for E10 Petrol (10% ethanol 90% gasoline by volume), by mass is 43.54 MJ/kg, by volume is 33.72 MJ/L
The energy density for water, by mass is 0.001 MJ/kg, by volume is 0.001 MJ/L
The energy density for a torch battery, by mass is about 1.4 MJ/kg
References
1. Syvret, Paul. Ethanol fuel is not so green. http://www.news.com.au/couriermail/story/0,23739,23107613-5012321,00.html
2. http://en.wikipedia.org/wiki/Octane_rating
3. http://en.wikipedia.org/wiki/Energy_density
This may be true, but it also reduces the efficiency of the petrol in your car. If you add 10% ethanol to your petrol, you will find that your car travels 10% less kilometres on a given tank of fuel. Result: you have to buy more fuel to cover the same number of kilometres you previously travelled on petrol-only fuel.
How can this be? Well, it comes down to knowing the difference between the octane level of a fuel and its energy density.
The Research Octane Number (RON), or octane level, of a fuel is a measure of how easily it burns, while the energy density is a measure of how much work you can get it to do. I will spell this all out at the bottom of the article for those who want to know.
So, you add some ethanol to your petrol and your motor will happily burn it, just as though it was petrol. However, it won't do as much work as petrol, so you will cover less kilometres on a tank of this fuel mix than you would on petrol alone. In effect, you are being sold "watered-down" petrol; a bit like buying a litre of milk that has been thinned with water.
Lets not even consider that it takes nearly 200 kg of corn to create about 90 litres of ethanol (That same amount of corn could supply enough calories to feed a person for a year); or that the demand for bio fuels will drive the price of corn beyond the ability of people, who need it for food, to buy it. (1)
The simple fact is, if you "water-down" the fuel, we have to use more fuel to do the same work.
To sum up,(as you can see from the definitions below) Ethanol will burn as easily as petrol, even in high performance cars (where it probably burns better), but it will do less work than petrol. This means you will drive less kilometres on a tank of ethanol-mixed fuel as you would on a petrol-only fuel. The more ethanol in the mix, the less kilometres you get.
=================================================================
Definition of octane rating
The octane rating of a spark ignition engine fuel is the detonation resistance compared to a test mixture of iso-octane (with an octane rating of 100) and n-heptane (with an octane rating of zero).
The octane rating does not give you the energy content of the fuel, but only describes its tendency to burn rather than explode.
The octane rating used by most countries, including Australia, is the Research Octane Number (RON). In Australia it is the "headline" octane rating, shown on the pump. In America, their "headline" octane rating for a fuel is lower because it is calculated differently.
The RON of a fuel is determined by running it in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane. (2)
It is possible for a fuel to have a RON greater than 100, because iso-octane is not the most knock-resistant substance available. Alcohol fuels such as ethanol or methanol can have significantly higher octane ratings; ethanol's RON is 129
Ethanol has a Research Octane Number (RON) of 129
Regular Gasoline has a RON of a minimum of 91
Premium Gasoline has a RON of a minimum of 95
Definition of Energy Density
The Energy density of a fuel is the amount of energy stored in a given volume.
Energy per unit volume has the same physical units as pressure, that is Joules/Litre, or megajoules per litre (MJ/L) in the case of fuel.
If we were talking about food, the energy density would be measured in calories. (3)
The energy density for Ethanol, by mass is 30 MJ/kg, by volume is 24 MJ/L
The energy density for Gasoline, by mass is 46.9 MJ/kg, by volume is 34.9 MJ/L
The energy density for E10 Petrol (10% ethanol 90% gasoline by volume), by mass is 43.54 MJ/kg, by volume is 33.72 MJ/L
The energy density for water, by mass is 0.001 MJ/kg, by volume is 0.001 MJ/L
The energy density for a torch battery, by mass is about 1.4 MJ/kg
References
1. Syvret, Paul. Ethanol fuel is not so green. http://www.news.com.au/couriermail/story/0,23739,23107613-5012321,00.html
2. http://en.wikipedia.org/wiki/Octane_rating
3. http://en.wikipedia.org/wiki/Energy_density
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