LPG opinions - What's stopping people converting?

Buddy said:

My understanding of the heavy vehicles is that they actually have LNG on board as the fuel source. :

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That would make sense,.... LNG has to be kept cold to stop it expanding back into a gas, In the big lng ships they have a slow release value that slowly lets gas escape which as most people that have worked with gas bottles know causes cooling of the cylinder,.... this small leakage is then burned to power the ship and further refrigerate the tank so it is not wasted.

gfresh said:

Similar for Brisbane.. ULP $1.519 L .. LPG steady 68.9c. Massive difference.


CNG has some problems, in terms of efficiency it's energy per mass is a fair bit lower than LPG. It goes something like Diesel > Petrol > LPG > CNG... CNG is methane, whereas LPG is propane & butane, so there are some differences.

Ideally you'd have CNG/electric hybrid.. perfectly possible, and could result in costs of literally $10 a week for many hundreds of kilometers. Of course gumbyment wouldn't collect many taxes then - can't see them being that keen (this is the very sad thing about the western economies these days).

There is some hope though, I read something over in the US the other day regarding CNG being considered over there. So no doubt if they lead, we'll follow CNG is also utilised heavily in South America - http://en.wikipedia.org/wiki/Compressed_natural_gas

Korea is also big on LPG apparently, and a hybrid LPG/electric will be released over there soon, and talk is that it will be sold here. That may be the best for the moment unless CNG is pushed.

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I'm waiting for that hybrid or a plug in one before I buy my first car. I'm going to drive the bomb I got for free until that time. I don't want to buy any 'petrol' car.

And no CNG is probably the most efficient with petrol being the least efficient. The main problem is that engines converted to CNG, LPG or whatever don't have their engine reworked to improve efficiency. You need to change the timing yes, but to get the full benefits you also need to increase the engine compression ratio significantly particuarly on CNG. Higher compression ratio = greater efficiency. Most conversions don't bother disassembing and reworking the engine to do so because it would be highly expensive. If cars were sold and designed for CNG originally however....

The advantage of diesel is that has a different method of lighting fuel such that the max compression ratio is always close to being achieved. Mercedes Benz has adapted the compression ignition of a diesel in petrol engines recently as well.

Smurf1976 said:

The great problem with gas is that we're so busy burning it all for power generation that there won't be enough left to use it to replace petrol and diesel as well.

Industry may well talk of 100 years of reserves etc. But look at how much they're planning to export plus the boom in gas-fired power generation and it's nowhere near such an abundant resource relative to proposed extraction rates.

Depending on which study you look at, we're somewhere around 20 years from peak gas in Australia. Quite a few others have already peaked - for example US, Canada, UK, NZ.

I think we'll see the future of gas pricing as that of a petrol substitute rather than the coal substitute that many see it as today. That'll give us another energy price crisis - gas and electricity for home and business use as well as transport fuels.

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Couldn't agree more Smurf. I think its wrong policy to use gas for power generation, and even worse for heat generation in industrial processes (e.g. Alumina industry). It's far to valuable to send up the chimney stack. Should be used as feedstock for petrochemical, and as I have advocated, as a transportation fuel. But I doubt if there will be any change and Asia will still be plundering our (and others) gas reserves and sending it up chimneys, leading to the next energy crisis.

In the meantime, I still want to buy a CNG factory made car such as the Civic GX, and fill it up using towngas at home. And instead of fluffing around like krudd and parret, have the government show some leadership on this issue. But they are so dumb I dont think the can grasp that there is a viable solution (yes OK, short term, but it gives us time to work on the long term solution) right in front of their noses, that can be implemented now. I digress, but I think they are total idiots and I dont think Garnaut is far behind (why have we got an economist driving this highly technical debate). I am hardly surprised that all he can come up with is another level of taxation that will probably destroy the Australian economy, will achive absolutely zip in the total world CO2 level, and force people to become cave dwelling luddites.

aleckara said:

I'm waiting for that hybrid or a plug in one before I buy my first car. I'm going to drive the bomb I got for free until that time. I don't want to buy any 'petrol' car.

And no CNG is probably the most efficient with petrol being the least efficient. The main problem is that engines converted to CNG, LPG or whatever don't have their engine reworked to improve efficiency. You need to change the timing yes, but to get the full benefits you also need to increase the engine compression ratio significantly particuarly on CNG. Higher compression ratio = greater efficiency. Most conversions don't bother disassembing and reworking the engine to do so because it would be highly expensive. If cars were sold and designed for CNG originally however....

The advantage of diesel is that has a different method of lighting fuel such that the max compression ratio is always close to being achieved. Mercedes Benz has adapted the compression ignition of a diesel in petrol engines recently as well.

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Alec,
If you have a look at my posts you will see that I am pushing CNG factory made cars. Definitely not conversions - bad idea. They already exist (Honda Civic GX and Toyota Camry) but not in Australia. That's what has to change.

Buddy said:

Couldn't agree more Smurf. I think its wrong policy to use gas for power generation, and even worse for heat generation in industrial processes (e.g. Alumina industry). It's far to valuable to send up the chimney stack. .

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Gas combined cycle plants operate at about 60% efficiency, so it's one of the best ways to make electricity, I think the internal combustion engine operates at 6%.

If we used electric cars it would be far mor efficient to burn the gas in a combined cycle plant then charge electric cars than burn the gas in a internal combustion engine to power the car directly you would lose about 10% efficiancy in transmission and charging but 50% is still far better than 6%.

Electric cars are a few years off but.

Tysonboss1 said:

Gas combined cycle plants operate at about 60% efficiency, so it's one of the best ways to make electricity, I think the internal combustion engine operates at 6%.

If we used electric cars it would be far mor efficient to burn the gas in a combined cycle plant then charge electric cars than burn the gas in a internal combustion engine to power the car directly you would lose about 10% efficiancy in transmission and charging but 50% is still far better than 6%.

Electric cars are a few years off but.

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Yes, I agree about the efficiency of gas cogen (but depends on whether you live in the North or South i.e. temperature). Not sure about the 6% for internal combustion though - maybe someone else has that number at their fingure tips. But using gas for power generation, in my view, is the wrong way to go, especially for base load even if it is cogen.

I think you are saying that generating electricity using gas, and then having electric cars is more efficient that just using gas directly in the vehicle. I'm not sure I can comment on that because it's a very complex issue - cost of infrastructure, life cycle cost of batteries, blah blah. You may be right though. But I guess the point is that, it would take quite some time to build the cogen plants, plus electric vehicles still have some way to go before they are viable. Gas powered cars are available now (but not in Oz), the gas is available (unless you live in WA, such as I do - ha ha) via towngas reticulation, and Wesfarmers are building mini LNG plants already to allow for country distribution. It's all there! Almost! Except for the government!

Tysonboss1 said:

I think the internal combustion engine operates at 6%.

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I thought they were much more effecient, more like 43%, but a quick search suggest the are more like 20-25% effecient.

http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Sarah_Carter/

SevenFX said:

I thought they were much more effecient, more like 43%, but a quick search suggest the are more like 20-25% effecient.

http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Sarah_Carter/

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The engine its self may operate at 20% but the is no way the car over the average trip will maintain over 20% efficency,... you have to factor in energy lost during braking and idling.

For example from the moment you switch your car on the engine is working at about 20% efficiancy, meaning 20% of the energy in the fuel is being used for mechanical work, the other 80% is being lost in heat, sound, friction etc,etc. however even though the engine is working at 20% you havn't even put it in gear yet so at this stage the car is operating at 0% because none of the fuel being used while you sit there idling is getting you to your destination.

once you accelerate away the engine is still working at 20% as you approach 70km/hr, but then you see a red light so you step on the brake there fore losing all that energy(fuel) that you spent to get to that speed, you then sit there at 0% efficiany while you wait for the light to turn green... so overall with all the braking and idling your effiancy would drop below 10%.

An electric car however doesn't sit there idling the electric motor won't draw power till you need to move,... and when you step on the brake, using regenerative braking it recaptures some of the energy back into the battery,.... also as mentioned earlier instead of burning the fuel in a 20% efficant combustion engine you are burning it is a highly efficiant combined cycle plant, so not only are you getting a larger amount of useful energy from the fuel in the first place but in an electric car you would be getting much better use out of the energy.