Hybrid Cars Burning Gas in the Drive for Power

Using hybrid for performance is going to the wrong direction. I can't believe companies are not using this wonderful technology to solve our world's problem, but to satisfy some customers' needs. Disappointed! :cussing:

 

Either way, i say that Hybrids will improve gas mileage. It's the domino effect. Technologies will improve. Even if you take the 400h, it has better gas mileage and it's faster. It's the superior suv out there. The next generation will be faster and more fuel efficient. All car companies do this in part. Toyota is at least taking the plunge to make the best fuel economy emprovement out there.

I tend to not care for complaining abut the problem. The companies work the way they work. good luck changing that. At least we have a few who recognize a good technology for the better of the world, and their pocketbooks of course.

 

Power vs Emissions

[font=Comic Sans MS:af8ebd0047]And ALL hybrids have lower emissions that conventional ICE cars. Maybe new technologies, like hydrogen fuel cells, will polute less in the future, but for now, even if people by them for the power, we can all breathe a bit easier.[/font:af8ebd0047]

 

Re: Power vs Emissions

<div class='quotetop'>QUOTE(Bill Merchant\";p=\"108881)</div>

There is no SMOG related emission (NOx) reduction whatsoever from some hybrids, like Accord-Hybrid.

That's where the "SULEV" and "PZEV" labels apply. They have absolutely no correlation to to efficiency, since MPG only affects CO2 type emissions.

 

[font=Comic Sans MS:b0c4a06f0e]Thanks for clarification, John. I made no distinction on purpose. Since you draw the distinction, even if there is no reduction in NO[sub:b0c4a06f0e]x[/sub:b0c4a06f0e], I consider it a good thing if less CO[sub:b0c4a06f0e]2[/sub:b0c4a06f0e] greenhouse gas is going into the air.[/font:b0c4a06f0e]

 

Re: Power vs Emissions

<div class='quotetop'>QUOTE(john1701a\";p=\"108892)</div>

I don't understand what you just said. Can you clarify? wouldn't all emissions be linear to the fuel burned ( i.e. mpg)?

dave.

 

Re: Power vs Emissions

<div class='quotetop'>QUOTE(dstrout\";p=\"108911)</div>

No problemo. It's a very common misconception.


CO2 (Carbon Dioxide) is a harmless to humans. We can breath it into our bodies without any negative effect. The atmosphere, on the other hand, is harmed. CO2 traps warm air. That warmth affect storm systems, causing them to pour down on us more often and to greater extremes... as you may have already observed by our record-setting summer & winter temperatures and increased tornado & hurricane activity.

Engine combustion creates CO2 as a by-product. Higher MPG is the direct result of using less fuel. So using less means less CO2.


NOx (Nitrogen Oxides) are poisons to humans. They contribute to breathing-related health problems, like asthma. This is what is referred to as "smog", that nasty yellow-orange haze that floats over metro areas. It is the direct result of incomplete combustion and poorly cleansed exhaust.

In other words, it is the way in which the fuel is combusted that matters... not how much is actually used. That's where the Atkinson-Miller pumping cycle of the engine used in Prius comes in (rather than Otto, which most dirtier vehicles use). This delivers a cleaner (and more efficient) method of combusting the fuel; however, less horsepower is generated as a result. But since Prius has a powerful electric-motor too, the horsepower tradeoff isn't an issue at all.

The other part that matters is how the exhaust is handled, which has absolutely nothing to do with the design of the engine. Cleansing takes place in the CAT (catalytic-converter), a rather expensive device in the piping between the engine and the muffler. Emissions from the engine are chemically altered in CAT the using heat to remove NOx molecules from the exhaust. The result is what's measured to award an "ULEV", "SULEV", or "PZEV" emissions rating... not MPG.

 

As it as been named in Peak Oil, Jevon's Paradox.

"as technological improvements increase the efficiency with which a resource is used, total consumption of that resource may increase, rather than decrease. In particular, Jevons' paradox implies that the introduction of more energy efficient technologies may, in the aggregate, increase the total consumption of energy".

Also, when has it been a tax credit to get a hybrid? It's been only a tax deduction so far which is an entirely different ballpark.

 

Re: Power vs Emissions

<div class='quotetop'>QUOTE(dstrout\";p=\"108911)</div>

You are correct, and john1701a is wrong.

NOx is measured in ppm, and CO in percent. These are not absolute measures, but relative to the amount of exhaust gases emitted from the tailpipe. So a car that produces X ppm of NOx and gets 60mpg is creating 4x less NOx on an absolute scale than a car that also produces X ppm of NOx, but only gets 15mpg. The same applies to CO, which is measured as a percent.

It should be intuitively obvious that what john1701a wrote couldn't possibly be correct. Otherwise, cars that got worse mileage would have to produce cleaner exhaust (measured in ppm or percent) than cars that got better mileage. Obviously this isn't the case, and what he wrote was nonsense.

 

Correct me if I am wrong but, I thought the Prius was originally designed to be more environmentally friendly, and improved mpg was merely a more than welcomed aftereffect. At least that is what I heard from corportate representatives at a workshop held at my dealer.

Also it is possible that introducing more hybrids to the market showing consumers that there are more benefits than fuel efficiency and decreased pollution may increase receptiveness and open the door for more fuel friendly hybrids in the future.

 

<div class='quotetop'>QUOTE(NiMHpwr\";p=\"108988)</div>

I personally believe it's the other way around. Having improved MPG has more of a marketing/economics incentive than being green. Being nicely green just was possible along the way.

After all, that was the goal of the original Buick hybrid in the '70s during the oil crisis.

 

Over here, at least, all the marketing blurb primarily talks about it being environmentally friendly. They seem to equally emphasise the low CO2 and low other emissions.

The press and public are generally more interested in the MPG.

As for pollutant measures, here cars are rated with CO2, NOx, CO, HC all in g/km - ie an absolute measure. There are absolute legal limits on all of those except CO2 (and you get tax penalties on that). Diesels are allowed to produce much more NOx and particulates, but the petrol and diesel standards a likely to be unified in 2010, meaning diesels will need much better exhaust filter systems.

The Prius emits only 20% or less of the current legal limits, so could be up to 5 times cleaner than other current petrol models. In practice its probably 2 times as clean on average. For smog-forming NOx and particulates its many many times better than a diesel.

 

Re: Power vs Emissions

 

I think you're both saying sort of the same thing. Let me try phrasing it in a different way:

"CO and/or CO2 (greenhouse gasses) are produced as a direct result of burning gasoline. Burning 1 gal of gas always yields X lbs of CO/CO2. NOx (smog) is also produced, but at varying quantities depending on the conditions under which the gas is burned."

Is that right? I think that's a 2 sentence summary of what you both said.

dave.

 

<div class='quotetop'>QUOTE(NuShrike\";p=\"108948)</div>

At the risk of coming dangerously close to the politics zone, I'm going to throw this thought out. It seems to me that Jevon's Paradox, and the idea of using hybrids to boost performance, is very american. As a nation we're going to have to get over the "bigger is better" idea. And not just on cars, but on everything -- cars, houses, buildings, empires, hamburgers, etc. Everything. And I think that's going to be a very, very hard shift to make.

It's like diesting -- the only way to lose weight is with a lifestyle change. The guy in the original NY Times article was a perfect example.

"I wasn't prepared to give up anything to 'go green' - not performance, amenities, or space,"

Until we figure out how to change that outlook ("I wasn't prepared to give up anything"), neither hybrids nor much else are going to cut down on overall consumption.

(Note: I'll be the first to say I'm guilty of it too. "Anything worth doing is worth overdoing" has been said to my kids way too many times. Trading my guzzler for the Prius has been my first visible attempt to change that lifestyle. But it's not a point you reach overnight)

dave.

 

Look up the EPA emission rating criteria. NOx is the primary substance. Included with it is HC & CO & PC. I didn't mention those because only a basic explanation was requested. Just looking up SULEV will provide details, listing the quantities for each substance based on vehicle class.

And whether the MPG non-correlation is intuiative or not doesn't make it any less true. When a vehicle is tuned for power & speed, it isn't necessarily tuned for as complete of a fuel burn as possible. It's a sacrifice that people with a lust for better 0-60 times are more than willing to make. They just claim their ULEV rating is much cleaner than vehicles from 30 years ago, ignoring the fact that SULEV is even cleaner.

 

<div class='quotetop'>QUOTE(Bill Merchant\";p=\"108881)</div>

Bill, if you look at the quote from the article, the nonhybrid and hybrid version of Accords are in the same EPA emissions category. So we don't breathe a bit easier with those kinds of "hybrid" cars. And they have about the same MPG. These ukeright: "fake hybrid" ukeleft: will be giving real hybrid (like Prius) a bad name. :x

Scott

 

<div class='quotetop'>QUOTE(KMO\";p=\"108999)</div>

Actually, new cars in the US do have to meet g/km limits, but those limits vary based on weight. There is also a fleet average that has to be met.

State smog checks performed after a car is sold measure pollutants in ppm or percentage.

 

Just to talk a bit more about tailpipe emissions, since there is still a lot of confusion ..

Air + Petrol -> heat, C02, and pollutants.

Air is O2, N2, CO2, and a smattering of minor gases
Petrol is long chain hydrocarbons (CH)x, with a taint of sulfur containing compounds.

The first useful thing to notice is that one of the major pollutants, NOx, is a byproduct of AIR all by itself. No atoms from petrol required.

Complete oxidation (also called combustion) of (CH)x leads to H20 and C02. The combustive product just before C02 is C0. In a modern engine, quite a bit more than 99% of the possible C02 than could theoretically be produced, is. The small fractions of one percent of incompletely combusted petrol show up in the exhaust as CO, NMOG, particulate matter, and so called hydrocarbons (a very bad term, since that is what petrol is. It probably refers to single carbon fragments that still have hydrogen attached). So incomplete combustion differences between two cars -- say one at 99.90%, and the other at 99.95% lead to the differences in hydrocarbon pollutants, but in terms of tailpipe C02, the differences are miniscule if equal amounts of petrol have been consumed.

Nox -- as far as I know -- is mostly produced when combustion chamber temperatures go very high. So called lean-burn engines develop these conditions, as well as high RPM states due to friction. It is tempting to say that similar conditions that promote Nox production also promote Sox production, but I do not know that for fact. Only thing for sure -- Diesel has a lot of sulphur in it, and diesel engines make a lot of Nox.

A small digression .. pollutants are measured in grams/distance traveled in the US, but in grams/fuel burned in Europe.

So, what does all this mean ?

1. Fuel consumption is directly related to CO2 production, +/- 0.005% or so. This is why, if two vehicles have traversed the same distance, CO2 differences are pretty exactly proportional to MPG differences.

2. Again comparing two different vehicles, tailpipe pollutants will NOT correlate with MPG. A hummer could theoretically use 10 times the fuel to move a mile compared to another car, but burn every single hydrocarbon chain all the way to CO2, and thus be very clean as far as CO and small carbon fragments go. A quick jump over to the NREL website shows the Prius G1 being put through its paces over different EPA and other load/routes. MPG figures change dramatically, but guess what ? The pollutants do not follow MPG, EVEN WIHIN THE SAME CAR.