Compressed natural gas cars

#1

milohimself

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#1
Was thinking in the $4/gal gas thread... Why not put this up? I was supposed to help run a drift competition today at Portland International Raceway, but it got canceled due to rain. So I ended up spending the last seven hours researching all the options I could with compressed natural gas cars. Here's what I came up with:

Why use a CNG car?

Honestly, I don't see any downsides to it. CNG is not very flammable, it has to be a 5-15% air to fuel ratio to be flammable. It's no worse than regular gas.

- It's far cheaper on a fuel-cost per mile basis: I'll get to that in a minute
- It reduces our dependency on foreign oil: 85% of natural gas used in the US is produced domestically
- Easy to get: You can refuel at home. We all have natural gas lines anyways
- Crazy low emissions: Say what you will about global warming, with all these other pluses, why not keep the tree huggers happy as well?

How do I get one?

This part can be a little tricky. If you're in the market for a new car, Honda is the only company in the US that current produces a car that runs off compressed natural gas, the Civic GX. They run about $25,000 new, though the fed. government offers a nice $4,000 tax break. Your state government might offer a nice tax break as well!

Another way would be to retrofit an existing car to run off of compressed natural gas. This part is a little tricky. Assuming you live in an area with emissions testing, it has to be done on a vehicle the EPA has approved for retrofitting. Not only that, but you have to use a kit that the EPA has approved to be effective. Not only that, but all the companies who make these kits don't simply sell them to the public; they are sold and installed either directly by the company themselves, or shops approved to do so.

The list of these cars and the applicable kits can be found here:
http://www.ngvamerica.org/pdfs/marketplace/MP.Analyses.NGVs-a.pdf

As a side note to this, this option can be extremely expensive, and it's recommended to convert to a dedicated natural gas fuel source as many government rebates are not offered to bi-fuel vehicles.

The third option for purchasing a CNG vehicle is purchasing used. Every once in a while you can find them on Craigslist or Autotrader. But the number one user of CNG vehicles is actually the government, and you can sometimes find used CNG vehicles for sale through government auctions:

GovSales - Home Page

Truth is finding a used CNG vehicle can be tough, but is usually the most cost-effective way to get one. At least of what I've seen from the Civic GX's available, they are not that much more expensive than their regular petroleum gas counterparts. Don't forget to Google your heart out to find a car.

The only thing I haven't researched so far is possible tax incentives offered on the purchase of used CNG vehicles.

What about gassing this beast up?

I would assume most of you haven't seen CNG options at your local gas station. Probably well enough.

A list of stations you can get gas at can be found here:

Alternative Fuel Station Locator - Find

Just plug in your info and off you go.

Oh wait, I forgot: The totally awesome sweet kick-ass part about a natural gas car is that you can plug in from your home, right? Yeah. Well, a specific company by the name of FuelMaker made a cool product by the name of Phill that you can use to refuel your car at home. An installer comes out, installs this thing off an existing gas line -- anywhere around your house -- and it works charms. Easy to plug into your car, can fill overnight, etc. The Civic GX takes approx. 16 hours, but most of the time you're looking at a 6-8 hour refill, if that. This is reported from numerous owners. And you can disconnect at any time.

index

Although they don't price it, as I understand it's around the mid $5,000 range to have one of these bad boys put in your home, installed. Sounded high? Wait, you guessed it. More tax breaks! Starting with a $1,000 tax break. State-level breaks are also usually available, along with other benefits. Natural gas suppliers in California, for instance, gives customers with Phill installed in their homes a low flat-rate fee for natural gas.

Milo, give it to me straight, how much is this going to cost?

Well, this whole thing really depends on where you live. What are fuel costs? How much is natural gas in the area? Are CNG cars and components easily located? Are there state-level tax incentives? Here's a good link on things:

http://www.ngvamerica.org/pdfs/FAQs_Converting_to_NGVs.pdf

Oregon, being the green state that it is, provides a relatively easy place for me to go CNG for my daily car. I plan on doing so. Some of you may as well, after reading all this. Some of you may not have the ability to do so easily. Talk to companies around the area who can help make this happen!

I've provided just a little info here and some sweet links. There's tons more to be discussed.
 
#2
#2
Some cost numbers from the EPA.

Cost to drive 25 miles:
2008 Honda Civic GX - $1.47
2008 Honda Civic - $3.40

2003 Ford Crown Victoria CNG - $2.95
2003 Ford Crown Victoria - $5.47

2001 Ford F150 CNG (5.4L V8) - $3.17
2001 Ford F150 (5.4L V8) - $6.57

2005 Chevrolet Silverado 2500 HD 2WD CNG - $4.58
2005 Chevrolet Silverado 2500 HD - $8.95
 
#3
#3
Milo...I didn't see in the links any discussion about the miles/kg of CNG for a car like the Honda. I searched around some...and I see that you can get about 180-200 miles on a tank...but I couldn't find the volume and maximum storage pressure in the tank so that I could see how many miles/kg that is.

I would need that to be sure and give exact numbers - but low emissions doesn't necessarily mean global warming friendly - though natural gas is more environmentally friendly in general than gasoline.

Also, the energy independence you bring up is important. While if we were to actually convert a large portion of our auto fleet to CNG it could mean we could no longer produce such a sizable fraction of the natural gas we use - friendly nations like Norway are large natural gas suppliers.

P.S. Thanks for putting all of this together. If I can find a little more info, there will be some "fun" calculations to do...
 
#4
#4
Thanks for the cost information as well..those are impressive numbers. I wonder how much price pressure converting half of our fleet to CNG would put on natural gas and relieve on gasoline...and how these numbers would change? The scale of the problem makes a priori (and non-modeled) cost comparisons difficult.
 
#5
#5
Honda states that the capacity of the tank in their Civic GX is 8.03GGE, or gasoline gallon equivalent. I calculated that to be roughly 10.6 therms. Of course that's not an exact number, as volume of gas changes with pressure and temperature. You're also comparing BTU's to petroleum gas. But that's about as good a number as I could come up with. CNG in cars is measured in GGE's, and I found one GGE to be equivalent to about 1.32 therms. If anybody can do better math than that, feel free to post up.

IIRC, CNG vehicles store gas at 3600psi, or roughly 250 bar.

I don't expect everybody to switch to CNG. It's not viable as a mass option. But it's something I'd prefer to do to save money and do my part. All my money and hopes for alternative fuel in the future relies on switching all transportation fuel in the US to algae-produced oil.
 
#6
#6
Thanks, milo. Algae-derived biodiesel does look like an option that might be able to be built up into a larger market. Thanks for posting the GGE numbers.
 
#7
#7
Actually, it's not even just biodiesel. A company in California produced legitimate 91 octane gasoline from algae.
 
#8
#8
Actually, it's not even just biodiesel. A company in California produced legitimate 91 octane gasoline from algae.

That's interesting. I suppose once you make the oil, you can turn distill/crack it into a variety of things. I assume that the efficiency is a bit better for biodiesel..but I don't know that.
 
#9
#9
Thanks, milo. Algae-derived biodiesel does look like an option that might be able to be built up into a larger market. Thanks for posting the GGE numbers.

How many Joules does it take to create 1 J of energy from this algae process? :unsure:
 
#10
#10
How many Joules does it take to create 1 J of energy from this algae process? :unsure:

For traditional biodiesel (soy), the number is about 3.2 Joules of biodiesel per Joule of traditional energy input (not counting the sun's input, that is). So, the Energy Return on Energy Investment (EROEI) is 3.2. Because the yields of algae are supposed to be A LOT higher per acre, then the EROEI for biodiesel from algae would likely be higher.

However, this is highly dependent on the scale of use...because if we really step up production, then we would likely need a lot more space...which means the dessert, probably. While the solar energy is a lot more prevalent there...water is not...so I would think that the EROEI would fall down some. I can't find a good analysis of this, though. Something else to remember is that processes like this do not see very good economies of scale...so increasing the scale would not necessarily save money in aspects like capital investment.
 
#11
#11
Doing some back of the envelope stuff...

I read that you can usually drive 180-200 miles on 1 full CNG tank in the CNG Honda...so I will use that as a basis.

190 miles in a car getting 30 mpg conventional gasoline will emit about 125 pounds of CO2.

If one tank of CNG is worth about 8 GGE (and assuming natural gas is only methane), then driving on one tank (about 190 miles) will emit about 110 pounds of CO2.

This seems reasonable....natural gas does have a lower carbon content than other fuels, but it still results in a lot of CO2 emissions. The CNG cars will certainly result in less emissions of other kinds...but when it comes to global warming arguments, you only get an 8% improvement in CO2 emissions at the tailpipe. If the CO2-cost of extracting, transporting, compressing, etc. the natural gas is less than the CO2-cost of similar processes for gasoline, then this improvement could be a bit more than 8%.
 
#12
#12
Bosch is currently developing a catalysis system for cars that can reduce CO2 to negligible levels. Emissions will take care of themselves. What we use as a fuel and where it comes from should be the only concern. The fact that algae can be produced entirely domestically and practically limitlessly is great. The science will get better and we can eventually get a better return of energy from producing it. And we don't necessarily need desert space to produce the stuff; it can be harvested in literally any water. We can produce it in existing landfills. IMO we already have the space and capacity, now we just need the method.
 
#13
#13
Bosch is currently developing a catalysis system for cars that can reduce CO2 to negligible levels. Emissions will take care of themselves. What we use as a fuel and where it comes from should be the only concern. The fact that algae can be produced entirely domestically and practically limitlessly is great. The science will get better and we can eventually get a better return of energy from producing it. And we don't necessarily need desert space to produce the stuff; it can be harvested in literally any water. We can produce it in existing landfills. IMO we already have the space and capacity, now we just need the method.

Is the system being developed by Bosch to be used with CNG vehicles? The only thing that I can think of is CO2 reforming of methane to make hydrogen and water - and then the hydrogen could be combined with the CNG in the engine...but I bet this would burn hotter...so maybe more NOx (though this could be catalytically converted as well). I have no idea if this is what you are talking about or something else....it is the only thing that I can think of that could reduce CO2 levels from an engine...outside of CO2 adsorption...but that couldn't be done on a car. There could easily be something else, I just can't think of what it would be...
 
#14
#14
I heard it in a conversation today in class. Let me clarify. Bosch has a catalysis system that reduces NOX on diesel vehicles to negligible levels.
 

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