Diesel: pro's & con's

[zaxrex]

Actually, this is a good topic, just going off of the wrong thread. Anybody have objections to splitting this off at post 6 and having a new thread on socio/political/economic implications of diesel engines? We all can play nice and see different aspects of the issues...

[WRXWagon2112]

I second the motion!

--Alan

[Mr Kleen]

dew eat

[GaToR]

Great idea Zak.

Maybe a little history will air some misconceptions. If the US had had to pick one fuel type to power its economy over the last century, and likely far into the next century, it is fuel oil. In its refined state we know it as diesel or kerosene.

1) transportation relies on it. the trucking, rail industry, aviation industry all use it

2) all heavy equipment relies on it. namely construction, agriculture

2) US military trucks, tanks, aircraft and most ships use it

It is already economically viable for these sectors because they don't pay retail like we do at the pump. To them, diesel is still significanly cheaper to purchase than gasoline, and in super-high torque applications that 30+% increase in fuel economy is a must! That is their overhead.

The example of one fuel station price-gouging diesel fuel is a great example of what the problem really is. We, the consumers, pay retail. Considering that only 1/10 pumps at fuel stations is diesel, that gives them the opportunity to raise the price simply because less competition and supply/demand. If there were as many pumps available for diesel to the car driver, we'd probably see prices drop. There is no revolution necessary, just minor changes to the existing infrastructure.

[WRXWagon2112]

Keep in mind that there have been few, if any, new refineries built over the last, what?, 20 years? Mostly due to NIMBY and environmental regulations. This leads the existing refineries with difficult choices to satisfy the American consumer's thirst for fuel: make diesel or the various blends of gasoline?

I think the similar price you're seeing for diesel compared to mid-grade gasoline is partly the result of refineries trying to balance their output among the various products. The price may reflect, not so much the true cost of diesel, as the "supply manipulated" price. If the refineries were to balance out their processing of diesel (for consumer consumption) with gasoline you may find the price dropping considerably.

I also foresee diesel as being much more resistant to future taxation since it is so vital to all other sectors of the economy. There's few politicians who'll risk their career over taxing diesel fuel.

--Alan

[scheherazade]

True, "relying on it"... that is probably why bio fuels are such up-and-comers.

I think bio-fuel is going to have at least a day in the lime-light (regardless of whether or not it makes sense) because it is a drop-in replacement for a nation worth of already-existing vehicles. You can't switch the entire country to some totally foreign energy over-night, but you can pour bio-fuel...

Has anyone done any calculations on how much surface area you would need to plant, to produce fuel at a rate capable of sustaining our current consumption?
It would be interesting to know if bio fuels are actually capable of replacing fossil fuels, due to sheer volume vs. growth-rate.

Also, the impact on the soil if it had to constantly grow fuel crop. Would it eventually be 'dead soil' (low/no nutrients), and how long would that take?
Are burned nutrients going to return to the soil (via rain?) in a form that is useful for plants? Are people getting into something that is literally going to be throughput-capped in order to not have another dust-bowl?


I guess I only ever hear about the marketing material, or the 'we hate bio' material. Both of which I don't really trust to be objective.

What I'd like to see is a "what if we relied on this 100%, for 200 years" type analysis. I'm curious what the results would be.

I also foresee diesel as being much more resistant to future taxation since it is so vital to all other sectors of the economy. There's few politicians who'll risk their career over taxing diesel fuel.

They could make industrial/commercial applications tax-exempt.
And leave private consumption taxed.

Truckers could have a card that they swipe to put the pump into tax-free mode. Or something... I donno...

-scheherazade

[Mr Kleen]

Has anyone done any calculations on how much surface area you would need to plant, to produce fuel at a rate capable of sustaining our current consumption?
It would be interesting to know if bio fuels are actually capable of replacing fossil fuels, due to sheer volume vs. growth-rate.

Also, the impact on the soil if it had to constantly grow fuel crop. Would it eventually be 'dead soil' (low/no nutrients), and how long would that take?
Are burned nutrients going to return to the soil (via rain?) in a form that is useful for plants? Are people getting into something that is literally going to be throughput-capped in order to not have another dust-bowl?

a Car and Driver article talked about this a while back. short answer? current tech biofuels can't replace gas.

I also have a real moral issue with using food to power cars when there are starving people in the world.

[Sabre]

but it's used food that would normally just go out to the trash!

[zaxrex]

The easiest way to produce bio fuels now is to convert crops that can also be used as food. But it is not the only way. In the near future, there will not be enough bio fuels produced to even meet the additional growth in demand, regardless of type of substrate or process used.

Brazil has gotten to the point where in one month's time, they have clearcut/burned 2,500 square miles of rainforest. Part of that land will be used for bio-crop production. So we are shooting ourselves in the foot if we take a similar approach.

But in reality, alternative fuels won't make a dent in consumption of normal fuels until we force a change, socially and economically. That is going too slowly for me.

In the interim, biodiesel co-ops and waste veggie oil conversions are viable for the concerned and motivated individual. It is not a solution.

Diesel fuel vehicles have not had the environmental restrictions that gasoline vehicles have had. Because of this, they will always have the perception of "dirty". Reformulated diesels running in newer engines with catalytic converters on them will have better environmental impacts than gasoline vehicles. So that is nice...

[zaxrex]

but it's used food that would normally just go out to the trash!

That is only Waste Veggie Oil processing. Bio diesel can be made out of unrefined plant oils. In that respect, it can be a direct competitor for food crops. There is not enough food grade oil that can be used for processing to meet an energy demand.

The one nice thing is, the residual waste from processing can be used to re-introduce nutrients back into the soil, so it is partially sustainable.

[GaToR]

In the interim, biodiesel co-ops and waste veggie oil conversions are viable for the concerned and motivated individual. It is not a solution.

Agreed, it is not a solution, but it is an alternative for the environmentally conscious now until something more permanent becomes available.

How good of an alternative? Well, it has already been stated that a compact diesel can get up to 75mpg. That's about 30% better than our favorite compact hybrid, the Prius! And if the Prius is getting 30% better mileage than other compacts, that puts a well-done diesel at greater than 50% efficiency improvement over gas for vehicles with similar weight and torque.

A diesel-electric car might do even better, but there's a lot to be said for the denser fuels. Gasoline just isn't all that efficient as a combustible material, which is why all the industries use diesel widely.


In rough terms, look at the Audi R8 4.2 V8(gas) and the potential development of the 6.0 V12(d) :
The diesel version of the same car gets nearly 2x the torque, plus 1.5x the mileage with 1.5x the displacement. That means that on a displacement x weight x torque / mileage, the diesel is just over 4 times as efficient as the gas.

Does that mean the same vehicle can get 4 times the fuel mileage with all other factors being equal? Actually yes. If you applied this to extremely-high torque applications, like ships and semi-trucks, the difference becomes exponentially better. Which is why they don't bother with 10+ liter gas engines since WWII.

Because it combusts slower due to compression, as displacement goes up and peak RPMs go down, diesel actually gets more relatively efficient, while gasoline plummets in efficiency in high-torque applications.

Semi-trucks use 10+L engines and weigh 40 tons. A 12L diesel can be twice as relatively efficient as a 6L diesel. While a 12L gasoline engine is much less relatively efficient as a 6L gas engine.

i.e. once you get to the scale of a 10,000 ton US Navy Cruiser, a gasoline powered one might not make it out of port on full fuel bunkerage.

They just need to shrink these ratios down to scale for our economy cars.
Which is why for a little 2.0L diesel, the potential is there to get way better than we even currently think possible in terms of torque and economy. VW corp seems to have cracked it, but we'll likely see some improvements over time. Perhaps the Japs can shed new light on efficient diesel tech the same way they did with compact cars 20 years ago.

[scheherazade]

The plug-in electrics (don't laugh) seem like a decent alternative for short range commuters.

They can charge over-night, and they have a 200+ mile range (ok, the tesla roadster does... but nothing stops ford from doing it too).

For someone who drive 5 miles to work and 5 miles back, the car can as good as erase fuel costs. It's not free.. but it's pretty darn close to it.

They'd still need a car to 'go the distance', but for around town... I wouldn't be surprised if the idea picked up.



I can see the diesel-electric-plug-in as being a possible hit.
Plug in over night, and drive around-town, literally never using the diesel.

If electric power gets low, diesel starts up. Maybe near 1/5 tank or so.

-scheherazade

[drwrx]

The plug-in electrics (don't laugh) seem like a decent alternative for short range commuters.

While I agree with this in general, if everyone used plug-in electrics for commuting our demand for electric power would far outstrip supply. The public would create such a spike in demand that rolling blackouts would be required accross the nation starting at around at 4pm eastern time and not stopping until 8pm pacific.

And I won't even get into what an enviromental disaster the production and disposal of the batteries would be.

[complacent]

And I won't even get into what an enviromental disaster the production and disposal of the batteries would be.

That's my number 1 gripe.

Batteries. Are. Horrible.

[GaToR]

Military Hybrids

An interesting article in defense contractors' efforts to sell the military more eco-friendly trucks, since they long for that extra 30% fuel efficiency. Every gallon used is a gallon that has to be shipped over 2 oceans and trucked across the desert just to reach our troops.

I was looking for the hydraulic hybrids, since batteries are as environmentally hazardous as the emissions they replace. Basically its like airbrakes in reverse - using braking energy to pump brake fluid into a reservoir where it compresses Nitrogen gas, which is then released upon accelerating.

At first I wasn't thrilled about having hot oil stored at 5,000psi and then giving way on an F-150 accelerating onto a major highway. That'll make for a fun driving situation. But then you think about the fact that there are millions of trucks with airbrakes, or Nitrogen-filled shock absorbers, and they only fail as often as anything else that isn't well maintained.

Once again, however, there are only so many Joules of energy you can store during braking, so ~30% efficiency is still the norm.

Bottom line: for right now there is no 100% viable alternative energy source. The only thing we can do is reduce and improve on what we have. With the right tuning, a compact diesel could get 75mpg alone. Combine that with an easily disposable hybrid system (like hydraulic fluid), and we could see 100mpg out of cars... that still feel like cars.

[WRXWagon2112]

According to Bob Lutz, diesels won't gain much traction in the U.S. He thinks that ethanol is more likely to catch on with American consumers.

In the fuel economy and future tech debate, the hybrid vs. diesel vs. hydrogen fuel cells vs. smaller cars and smaller engines always provokes a fair bit of discussion among Autoblog commentators. At this point, no one yet knows what's going to win since nobody knows how the volatile mix of products, timelines, prices, regulations, legislation, state standards, and gas prices will ultimately pan out. Bob Lutz's prediction is that diesels, at least as far as the US is concerned, won't be much of a factor.

His reasoning is simple: "I think customers are going to say, 'Wait a minute. At equal fuel prices I'm paying $4,000 more for this." Unlike many countries in Europe, the US offers no incentive for people to buy diesels. In the States the price of a diesel vehicle is often more than $1,000 higher than that of a gasoline-engined car, and diesel fuel is just as expensive as gas (throughout California and other states, it's slightly more expensive than premium unleaded). In that case, Lutz's opinion is that just about all the customer will glean from an oilburner is a higher car payment.

Lutz sees diesel uptake in the US hovering at about eight-percent. The technology he sees as winning the day: ethanol. It's clean, it's easy to integrate into the refueling infrastructure, and it "doesn't require a change in consumer behavior." (Except for the people in emerging markets who've seen the price of corn skyrocket.) For another take on the fuel economy battle, according to Kelly Blue Book, 40-percent of US new car shoppers think hybrids are the future, with just 17-percent citing flex-fuel.

--Alan

[GaToR]

According to Bob Lutz, diesels won't gain much traction in the U.S. He thinks that ethanol is more likely to catch on with American consumers.

In the fuel economy and future tech debate, the hybrid vs. diesel vs. hydrogen fuel cells vs. smaller cars and smaller engines always provokes a fair bit of discussion among Autoblog commentators. At this point, no one yet knows what's going to win since nobody knows how the volatile mix of products, timelines, prices, regulations, legislation, state standards, and gas prices will ultimately pan out. Bob Lutz's prediction is that diesels, at least as far as the US is concerned, won't be much of a factor.

His reasoning is simple: "I think customers are going to say, 'Wait a minute. At equal fuel prices I'm paying $4,000 more for this." Unlike many countries in Europe, the US offers no incentive for people to buy diesels. In the States the price of a diesel vehicle is often more than $1,000 higher than that of a gasoline-engined car, and diesel fuel is just as expensive as gas (throughout California and other states, it's slightly more expensive than premium unleaded). In that case, Lutz's opinion is that just about all the customer will glean from an oilburner is a higher car payment.

Lutz sees diesel uptake in the US hovering at about eight-percent. The technology he sees as winning the day: ethanol. It's clean, it's easy to integrate into the refueling infrastructure, and it "doesn't require a change in consumer behavior." (Except for the people in emerging markets who've seen the price of corn skyrocket.) For another take on the fuel economy battle, according to Kelly Blue Book, 40-percent of US new car shoppers think hybrids are the future, with just 17-percent citing flex-fuel.

--Alan

I agree that diesels have a stigma against them in the US. But I see Lutz going either one of two routes: either he is a) a complete moron, or b) a complete asshat. I'm leaning towards the latter.

I also have a real moral issue with using food to power cars when there are starving people in the world.

First off, yes. Ethanol comes from corn seeds, which feed both the livestock and grain industries. It is not taking a byproduct of food production, but adding competition and cost to the very food we eat.

It is also not sustainable. We calculated in an Agronomy class that you could cover the entire surface area of North America with corn and you could not meet our current fuel demands.

Corn is also an environmentally unfriendly plant to grow. It is the main reason crop rotation is necessary in the midwest. Each year it is planted, it saps 3 years worth of nutrients from the soil. You then need 2 years of rotation crops to re-energize the soil.

But since fuel pays more than food, farmers are uprooting other crops just to make more money in the short term. And Iowa is doubling the number of distilleries over the next 5 years.

So in summary, the dangers of ethanol are:
1) Rising food costs, lack of food aid to developing nations (i.e. starving the world to fuel our cars)
2) Turning the midwest into a desert after all the fertile soil has been washed off by 5-10 years of continuous corn planting.
3) Ruining the agricultural economy when the supply can't meet demand and another alternative is sought (i.e. the farms go bankrupt, the distilleries go dry)

For me, if this is GM's solution, may they continue to crash until they are no longer a factor in the automotive industry. My point is that diesel is not going anywhere for 15-20 years in the other industries, and it holds much promise for the consumer market as well. GM has the technology available to make clean diesel as well. There's nothing inherently wrong with a Duramax.

But they have invested so much in the Yukon and Tahoe hybrid, I can see why they would want to snuff diesel. They complain about diesels having a $1K higher purchase price, but hybrids average $4K higher, and don't get as good highway economy. The only reason they can compete is government tax rebates, which if you read this thread:

http://forums.dcawd.com/viewtopic.php?t=5969

those won't last forever either. This is very shortsighted for GM, and a dangerous path for our economy to travel. Unfortunately he's right. It is likely to catch on, but that is because there is as much power in the US Corn Producers Association in Washington as there is for Big Oil.

[Mr Kleen]

the rising cost of corn is already being felt by small cattle ranchers in Kentucky. My dad's father-in-law isn't getting anywhere near last season's price for calves because nobody wants to pay for the corn to feed them.

ethanol is bad science foisted upon the citizens by lobbyists for the agri-corps and politicians.

[scheherazade]

And I won't even get into what an enviromental disaster the production and disposal of the batteries would be.

That's my number 1 gripe.

Batteries. Are. Horrible.

Yep.
Which is why we should use these things :

http://www.maxwell.com/ultracapacitors/ ... ap3000.asp

Small (for a capacitor of this capability), stupid-high power storage (for a capacitor), very high efficiency, and takes a bazillion more cycles than a battery before it's due for retirement.

-scheherazade

[Libra Monkee]

You know what cars need? Hamsters! Lots of hamsters! On little tiny wheels. Instead of horsepower it'd be hamster power. Just make sure you feed them and change the paper at the bottom of the engine every so often.

[complacent]

And I won't even get into what an enviromental disaster the production and disposal of the batteries would be.

That's my number 1 gripe.

Batteries. Are. Horrible.

Yep.
Which is why we should use these things :

http://www.maxwell.com/ultracapacitors/ ... ap3000.asp

Small (for a capacitor of this capability), stupid-high power storage (for a capacitor), very high efficiency, and takes a bazillion more cycles than a battery before it's due for retirement.

-scheherazade

Correct me if I'm wrong (may very well be, it's been some time since I've wired up more than 6 farads at once in an automotive environment) but aren't the nature of capacitors more of a transient storage device and not so much as an long term storage device?

If so, wouldn't that require some additional engineering as far as the production of electricity within the vehicle?

I'll try and go read up on these ultra-capacitors and let my ignorance hang out a little later on.

Definitely an interesting idea though.

[scheherazade]

Correct me if I'm wrong (may very well be, it's been some time since I've wired up more than 6 farads at once in an automotive environment) but aren't the nature of capacitors more of a transient storage device and not so much as an long term storage device?

If so, wouldn't that require some additional engineering as far as the production of electricity within the vehicle?

I'll try and go read up on these ultra-capacitors and let my ignorance hang out a little later on.

Definitely an interesting idea though.

They do leak. Slowly, but yes, they won't store literally forever.
Spec sheet shows 5ma of leak current on that cap.

And you can charge a cap so much faster than a battery. If your power supply can provide the juice, you could fully charge your electric car in minutes. Spec sheet shows peak current is 4800 amps, around 13KW at maximum discharge. Though they state 11KW peak 4KW sustained. *Per kilogram*. Charge rate should be pretty darn fast.

You could probably pair these up with some DC DC converters, maybe a zener+relay to cut it off when source voltage drops below useful. (Not giving a formula. I fix psu's sometimes, but I'm no designer).

Yes, caps are generally not used for storage, but they're also generally not that powerful. With some work, you could make them spoof a battery.

I *have* seen battery-type applications for these. Micro radio-control devices use micro super-caps for power.

Anyways, I'm sure there are caveats.
Generally the total stored energy (after complete charge) won't be better than a battery. The real benefit is being able to re-charge in no-time.

In my opinion, charge time hurts electric cars significantly.

-scheherazade

[WRXWagon2112]

Going back to E-SCI101 here so my depth of knowledge isn't that great in this subject but ...

Yes, capacitors charge fast, but they also discharge fast. And completely. Isn't the point of using a battery in an electric car so that the charge be drawn upon in a continuous manner? IIRC, a capacitor will simply release all it's energy instantly (or nearly so). It's primary purpose is for transient spikes in current - not as a continuous power source.

Hence the use of capacitors (ballasts) in fluorescent lights - it provides the initial "blast" of power needed to get the light started. But after that, the light only needs the steady flow of household current.

Can someone with electrical knowledge chime in? I'm thinking Zak could help out here.

--Alan

[Mr Kleen]

reguardless of how you store the electricity, you still have to make the electricity...

[ElZorro]

On the supercaps - for all intensive purposes they act like a very fast charging battery. (In general) they are great for situations with low current draw. Could you build a hybrid/electric car around super caps? Sure. But depending on the leakage rate you could walk out to your car after work and find it dead.

These arguments always come down to the same thing: storing energy. Gas/diesel/biodiesel/ethanol/batteries are all ways of storing energy.

For gas/diesel its easy: nature did a bunch of work for us already underground. Sure, we have to do some refining to get the junk out, but thats not bad. Add in some pumping and transportation.

Now, lets look at biodiesel. First, you have to grow a crop. This leaches minerals out of the ground, takes alot of resources (land, people, and more fuel itself for the vehicles, interesting article on fuel use in farming http://www.ext.colostate.edu/PUBS/FARMMGT/05006.html). Now we have to refine it. This is the same thing for ethanol. Gabe is right, farmers are already seeing the impact of ethanol, prices for feed have gone up. We've also seen it - cereal prices are going up and pretty soon we're going to see increases in anything that corn goes into (oh, and by the way, read ingredients, almost all sweeteners used in the US come from corn syrup, so that means beer, pop, candy, fast food...).

Lets look at an electric car. Where does its energy come from? The power grid. Where does that energy come from? The power plant. From Jan07-Oct07 48% of the power generated in the US came from coal. (http://www.eia.doe.gov/cneaf/electricit ... m_sum.html) Where does the coal come from. Well, we dig it up and transport it using diesel and electric powered machines (mining equipment and trains). Why do we keep using coal - because the US has a ton of it (http://en.wikipedia.org/wiki/Coal#World_coal_reserves)

This problem with storing energy extends to the vehicle. For gas/diesel/biodeisel/ethanol this isn't bad - you put a gallon in and with the exception of a little bit of evaporation you pretty much have the same amount of energy in your tank the next day if you don't drive. Now, for batteries (we'll put supercaps in this category) you don't - there is a small discharge rate.

An interesting article to look at (http://en.wikipedia.org/wiki/Energy_den ... nd_in_fuel). Has some good numbers on energy density of various things (gas, diesel, different types of coal).

If it came down to it - I'd say generate all of our power from renewable (solar, hydro, thermo, etc) or nuclear sources. Run as much as we can as electrical vehicles. For applications where electric doesnt work (military primarily) we maintain diesel. Yes, this would put a hurt on the power grid (as Darrin pointed out), but that something that we can fix - build more wires. (I know, copper costs are high - but no! overhead wires are made with aluminum http://en.wikipedia.org/wiki/Electricit ... ansmission)