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February 17, 2003

The Weak Link Of The Hydrocarbon Chain

You've probably seen a few ads that mention one of TLEV, LEV, ULEV, SULEV, and PZEV vehicles. In case you're not an environmental nut (and/or reformed automotive enthusiast) like myself, or haven't seen such ads, the alphabet soup above are the acronyms for California emissions standards of automobiles. They are Transitional Low, Low, Ultra-Low, Super-Ultra-Low, and Partial Zero Emissions Vehicles, respectively. Any further detailed explanation would be a cure for insomnia, so I'll simply state that they are listed in order from good to best in terms of lower vehicular emissions.

TLEV and LEV vehicles are available now, ULEV is becoming available in larger varieties, and if you really want a SULEV vehicle you can get one, but you're not going to have much choice. PZEV cars are... well, as few and far between as SULEV, but exactly what PZEV means is still fuzzy to me. Either way, American consumers have more choice in ZEVs, or Zero Emission Vehicles, than PZEVs or SULEVs, in the form a handful of battery electric vehicles currently in mass production. (Alas, Transport Canada is being a little too diligent in testing these vehicles, and as far as I know none of these vehicles are legal for use on Canadian highways yet. Way to go, Ottawa. But I digress.) If you're shopping for a car based on emissions, be prepared to do your homework - I can only think of one vehicle that was ever marketed based on its emissions level.

Low-emission vehicles are great, but they are still saddled with one emissions problem: they still fill up at a regular gas station. How is that an emissions issue, you may ask? Each time they fuel up gasoline drips from the nozzle onto the vehicle itself, the ground, and stays trapped in the nozzle, only to evaporate into the air. The emissions of modern vehicles are being constantly reduced - now how about we look at replacing the ancient filling station technology and eliminate another source of raw hydrocarbons? Do you remember a different technology in use when you were a kid to fuel cars? I didn't think so. The image above should be quickly recognizable as a gas nozzle. This particular specimen dates from the 1940s/50s. Yup - technology from two generations ago, folks. No matter how diligently you tap, tip, and shake the nozzle, there always seems to be one or two drops that manage to find their way onto the vehicle, the ground, or somewhere other than underneath the gas cap.

I haven't bored you with math for a while, so indulge me while I spell out the numerical mess that ancient nozzle technology is getting us into. To start off, I'm going to near-randomly assume that each time someone finishes filling their vehicle, they spill 2.5mL of gasoline. For the Imperially inclined, that's half a teaspoon of gas - not a large amount, and a fairly easy amount to spill if you're too hasty with the gas nozzle.

To compare all the different class of vehicle emissions, I've put together the table below. It shows which emissions standard I'm talking about, and the amount of Non-Methane Organic Hydrocarbons produced by such a vehicle in both grams per mile (lovely mixing of measurements there) and grams per kilometer. For the sake of comparison, I've included the Canada 1997 emissions standard, one that likely applies to most vehicles we see on the road today.

To complete the puzzle we need to know that gasoline has roughly three-quarters the density of water, at 0.721g/cc, or grams per milliliter. Thereby, our 2.5mL spill each time we fill up is equal to 1.8g of gasoline. To give a better indication as to how severe this spill affects each vehicle's emissions, I've calculated the equivalent distance that vehicle would have to travel to produce such hydrocarbon emissions, and also presented it in terms of the effective emissions rate and percent change, both based on an assumed 600km range on one tank of fuel. The results are as follows:

Spill Equivalent
Emissions Rate
g/mi g/km mi km g/mi g/km % Change
Canada 1997 0.260 0.163 6.9 11.1 0.265 0.166 1.8%
TLEV 0.156 0.098 11.6 18.5 0.161 0.101 3.1%
LEV 0.090 0.056 20.0 32.0 0.095 0.059 5.3%
ULEV 0.055 0.034 32.8 52.4 0.060 0.037 8.7%
SULEV 0.010 0.006 180.3 288.4 0.015 0.009 48.1%

As you can see, there's a reason gasoline nozzle technology hasn't changed in the past 60 years - it's had virtually no impact on the environment as compared to the vehicles' tailpipe emissions. Driving habits and improper vehicle maintenance will account for much more emissions than the spilled gasoline will. However, with ULEV and SULEV vehicles at hand and more on the way, those few drops of gas that spill account for a significant portion of the total emissions produced by those vehicles. I'll admit, at 50% worse than SULEV, you're still producing barely a whiff of pollution, even as compared to ULEV vehicles.

One would think that somewhere, somebody has already realized this problem and started thinking about better ways to fuel gasoline-powered vehicles. I've heard of exactly one such project. Shell opened an experimental automated gas station in California that robotically fuelled your vehicle for you. The aim of the project was not to change the delivery system of fuel to your vehicle, but to negate the need for you to actually do anything to fuel your vehicle. One portion of this project included a vapour return line from the nozzle that led to a vapour canister. Whether the nozzle spilled any less is still up for question, but at least the vapours released during refueling were recovered. Unfortunately, that was way back in 1998 - nearly five years ago. Have you heard of anything about it since? I haven't.

So, I've made my point, and shown what waste exists with the current technology. This is where I demand that action be taken, and that the spill-prone gas nozzles we use today must go, right? Nope. In all honesty, I figured I'd do the math and see results supporting the premise that gas station technology is outdated. I would declare first victory, and then war on the outdated evils at the world's gas stations. Instead, I see a different picture - one where relatively new vehicles are still allowed to pollute over twenty times more than the cleanest vehicles now available. If you compare vehicles that are even older, such as your neighbour's dilapidated 80's vintage Buick or even your uncle's cherry Pontiac GTO, that figure can skyrocket to over 800 times more pollution per distance traveled as compared to a SULEV vehicle. I will concede that SULEV vehicles are currently few and far between, but the technology is there - just give it a couple of years to make its way through full product lines.

Gas nozzles as they stand are still relatively ancient technology, and are something that could easily be done away with and retrofitted into extinction within a few years. However, the much bigger issue is allowing much older, dirtier vehicles to stay on the road polluting as much as hundreds of newer vehicles. I suppose your personal viewpoint may change depending on whether you feel more strongly about pollution or simply carbon dioxide emissions. Older vehicles shouldn't produce any more or less carbon dioxide than newer ones do of equivalent fuel economy - but they do produce way more harmful ground-level pollutants.

Maybe in another two decades I'll revisit the notion of gas pump nozzles as a large source of hydrocarbon pollution. With the average vehicle life at 15 years and rising, it will take at least that long, possibly much longer, for the majority of vehicles on the roads to be ULEV or better. Until such time, we'd be much better off creating more programs like Ontario's Drive Clean program, and expanding existing ones. Even more critically, we should be cracking down on falsified emissions certifications. All it takes is one bad polluter to negate dozens or hundreds of legitimately clean cars.

In the meantime, I'll still push to clean up our gas pumps and their ancient drippy nozzles. After all, just because a problem isn't the largest problem you have doesn't mean you shouldn't fix it if you can.


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