Best Ratio of Potential Chemical Energy vs. Cleanliness of Burn
 

Just wondering what would be the best ratio would be. Diesel has a high energy content but is very dirty. Gas/petrol is lower energy content, but cleaner. Is there any other fuel that would have a better ratio (maybe alcohol, natural gas, propane, bio-fuel, etc.)? I know bio-fuel is essentially zero carbon footprint, but leaving out the whole growing it first takes out CO2 thing...

Diesel has the highest energy content of any affordable commonly avaible fuel.
Its only dirty if you when you burn it at lower air fuel ratios.
Gasoline does the same thing in lower A/F ratios.

If you were to fumigate the intake of the diesel with natural gas or methanol, replacing diesel fuel energy with natural gas or alcohol it would run much cleaner.

You need to define this "ratio" more fully.
 

ANY of the common fuels available can be burned cleanly enough to meet Tier II - bin 5 levels. Are you speaking of measured cleanliness at the tailpipe? Or are you referring to "well to wheels" cleanliness?

If you are referring to the CO2 output per mile, it is hard to beat a diesel, all things being equal, for grams of CO2 per mile. If your bio - diesel is sourced from a low fossil fuel expended source, even better.

Waste vegetable oil in an older diesel application is about as low as you can go with this line of thinking of reducing CO2 emissions per mile.

Edison2 used E-85 in their Xprize car because they could/(were able to) burn it cleaner. They could have used gas or diesel and gotten the same phenomenal "MPGE," but as it stood with E85, their emissions were less than all the super aero electric cars charging from the grid.

But maybe there are other fuels like Hydrogen that pollute less or not all because of their chemical make up?

The Xprize did away with the emissions test.
 

At least with the original idea of running an FTP-75 cycle. In the end, it was a simple calculated grams per mile of CO2. By leveraging the bio-content of E85, Edison could show a "clean engine path". Meaning, they probably could pass the FTP-75 with a bit of work. They also could leverage the high octane of E85 to increase specific power and efficiency.

With the efforts to produce ethanol from cellulose sources, E85 could become a much more viable option. Thus, Edison could make the case for a fueling infrastructure.

Hydrogen is a clean fuel, if you can overlook the problems in production, storage and transport.

You are joking right?

I once read that water vapor is a greenhouse gas.

My original intention in this thought bubble was for tailpipe measurements, but "well to wheels" is certainly a very important figure as well, which I did not originally think about. Maybe an answer to both would be beneficial (if the answer would be different for both scenarios).

I was referring to all emissions, not just limited to CO2. Meaning sulfer dioxide, methane, particulates, etc. I wonder if bio-diesel pollutes those pollutants more or less than dino-diesel. I wonder if organic bio-diesel would be the best (cleanest) well-to-wheels fuel.

MMMMMMMMM. french fries!

I wonder if there is an efficient and clean way to "produce" hydrogen, like electrolysis. The issue with that though is the question of the efficiency of using energy to create the electrolysis vs. using that same energy to "fuel" a vehicle directly.

Is this in reference to current hydrogen production using natural gas as the source for H?

Yes sir! We talk about that in my Environmental Studies classes. We just don't generally refer to it as a GHG, because we don't see water vapor as "bad". But in essence, no matter what it is, if it is "up there", it will cause a greenhouse effect (to what degree and how unhealthy it is to our environment and our breathing is the deciding factor). Of course, water vapor can be considered bad if it mixes with molecules like sulfur dioxide, which creates acid rain.

Thanks for the replies guys!
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Found this article, pretty interesting: Clean Energy

Bio diesel burns much cleaner in my diesel and I have only used B20.
But I can't really use it during the winter.

Yes current and likely sources for the forseeable future.
Which will be natural gas, natural gas and coal at some point several decades down the road.

At the risk of sounding argumentative, how do you know bio-diesel burns cleaner? Have you tested it at a smog check or something? Why can't you use it during the winter? Is it because of crystal formation/solidification?

The B20 runs cleaner because there is virtulally no smoke during operation.
Remember I run no emmissions system what so ever, so what comes out the tail pipe is uncencored engine exhaust.
I would assume if I went from B20 to B100 there would be even less smoke.
B20 is the highest bio diesel concentration I have found and filled up with.

Bio diesel in NewMexico during winter will have the consistancy of pudding during a cold spell and will jell and cause filtering problems the rest of the time.

I took the time and ripped all the old rubber lines out of my suburban and replaced everything with biodiesel compatable stuff and installed larger primary fuel filters and installed stronger fuel pumps for running WVO.
Other wise I would be trying to avoid biodiesel. It tends to turn non biodiesel compatable rubber to black mush and cleans out gunk in the fuel tank just to redeposit it in the primary fuel filter.
I can run B100 or a 50% WVO/diesel mix today, None of the new diesels can do that.

Hydrogen is king with the best energy density, the best combustion result and the widest air/fuel ratio. However, it's reasonably impractical.

Consider BSFC for a bit, that is HP/HR/Lb of fuel consumed. BY WEIGHT, diesel and gas are closely matched. Not by gallon though.

E-85, can match modern diesel BSFC in specially designed engines. In other words, overall thermal efficiency can be excellent surpassing 45%.

But, the bottom line is and has always remained the same. Gasoline is very hard to beat for overall use.

This is a confusing post.
 

You make three statements that disprove your fourth. Explain a bit more.

You think my post is confusing, hahaha. You should experience my brain... (or what's left of my 3, functional brain cells)(just a little joke)

I was thinking about: Alcohol Fueled Heavy Duty Vehicles Using Clean, High Efficiency Engines and the promise of such. Having done development work with turbocharged race and street engines for 30+ years, I found the above quite interesting.

Then, recalled my time at Mobil Oil and the practicality of gasoline. It's easy, cheap and remains plentiful. A bit off subject. But that's how it goes with me... 3 brain cells, 3 different directions. :)

From an aviation standpoint, weight is what matters. And that's what I consider first. Volume being a secondary consideration. If Jet A and 100LL Avgas have nearly the same specific energy, then it's engine configuration that dictates the result. An interesting battle is shaping up between modern aviation diesels and modern piston gasoline burners. BSFC is what matters here. The winner is not clear yet. Both have quite similar BSFC numbers. The gas engines start/restart more readily in cold weather and at high altitudes.

Until you add in the weight of the tank required to store it and that the engine it is being burned in will have to be larger and heavier for a given power output. It does burn clean though.

I should think any fuel burned in a CI engine will be dirtier than that in a SI engine. They are always going to be run lean (= high NOx) and mixing the fuel and air is going to be more difficult (= high HC).

When considering a fuel, the energy released at a stoichiometric mixture, the moles of combustion products per mole of air and fuel mixture inducted (which with a given volumetric efficiency will affect the power output), the proportion of H2O and CO2 produced (and their specific heats at combustion temperatures) and octane or cetane rating are all going to effect the efficiency and, indirectly at least, the emissions per unit of useful work done.

In general, I suspect that the greater the proportion of H in the HC the better so yes, ignoring any knock on effect on vehicle weight, H2 will be the best. CH4 will look pretty good also.

You might think hydrogen is a great motor fuel, if you don't know anything else about it aside from its liquid state energy density.
Hydrogen fuelled vehicles are just a massively expensive overly complex answer to a problem that could be solved with BEVs. BEVs which don't need a very expensive fueling system built from the ground up.
Then you have the dirty little fact that almost all hydrogen produced comes from natural gas, not water.

The problem with BEVs though is the potential chemical energy is not as high with today's battery technology as other sources are (i.e. standard fuels). The other issue is where we get electricity from. Here in California, where electricity mostly comes from Natural Gas, a BEV would not be any better than a fuel cell vehicle that gets Hydrogen from the same source of NG (although the infrastructure would not be as difficult to implement).

I'm wondering how the energy to drill and process Natural Gas for Hydrogen development compares to the energy needed for electrolysis of water to produce the same amount of Hydrogen. At the same time, would solar/wind power make sense to power the electrolysis process. According to Wikipedia, the electrolysis of water is more efficient when salt is added to the solution.

Semi-random tangent question: Gas station storage tanks are notorious throughout history for leaking toxic gasoline into the ground. If a "gas" station supplying hydrogen had a leaky tank, would the hydrogen contaminate the ground in a toxic matter? If there was a leak could cleanup crews just oxygenate the ground to create water?

Answer: boost trailer, can be more batteries or a liquid fuelled generator.
I think liquid fuel generator is the way to go.


Who cares where the power comes from. Batteries are a lot cheaper than a fuel cell.
Having most of your electrical power come from natural gas is why California has some of the most expensive power in the country.
If some one really cares that much about where their power comes from they should go off grid with solar, wind and fire wood or natural gas.
Otherwise let the power company do its job and have them worry about the fuel source.

Both are horribly inefficient processes and amount to wasting resources. I ran all the numbers back in 2008, I don't remember the all details from 5 years ago but I do know it will not be economical in our life times.
Turning natural gas into hydrogen takes $4 worth of natural gas (1therm) and turns it into $10 to $12 worth of hydrogen (1therm). All you do is triple the cost of energy.

The main ground water contaminant was MMT, before MMT it was Lead.
Obviously we don't use Lead in auto fuel any more.
The U.S. very rarely uses MMT in gasoline, it may be completely banned.
Canada still uses it like its going out of style.
Problem is MMT mixes very well with water, its harder to separate than the hydrocarbons from the water and MMT is a nasty carcinogen.
Pure biodiesel would be easy to clean up, the esters would break down on contact with moisture and bacteria with a little air.

As a gas the H2 will find its way up into the atmosphere where it will ultimately be converted to H2O. Even if it did not there are biological process which result in free H2; it's benign.

Another aside with H2 is that if it is stored as a cryogenic liquid, such as might be the case in a car fuel tank, it is necessary to boil off some of the contents in order to maintain the tank temperature. Your H2 fuel tank must leak, by design.

The cryo servicing stuff I used to work with would boil off its contents after about 2 weeks or so.
If I had to fill up my car every 2 weeks even if I didn't drive it I would be finding another type of car.