Skip to comments.Few transportation fuels surpass the energy densities of gasoline and diesel
Posted on 02/14/2013 2:31:01 PM PST by thackney
Energy density and the cost, weight, and size of onboard energy storage are important characteristics of fuels for transportation. Fuels that require large, heavy, or expensive storage can reduce the space available to convey people and freight, weigh down a vehicle (making it operate less efficiently), or make it too costly to operate, even after taking account of cheaper fuels. Compared to gasoline and diesel, other options may have more energy per unit weight, but none have more energy per unit volume.
On an equivalent energy basis, motor gasoline (which contains up to 10% ethanol) was estimated to account for 99% of light-duty vehicle fuel consumption in 2012. Over half of the remaining 1% was from diesel; all other fuels combined for less than half of 1%. The widespread use of these fuels is largely explained by their energy density and ease of onboard storage, as no other fuels provide more energy within a given unit of volume.
The chart above compares energy densities (both per unit volume and per unit weight) for several transportation fuels that are available throughout the United States. The data points represent the energy content per unit volume or weight of the fuels themselves, not including the storage tanks or other equipment that the fuels require. For instance, compressed fuels require heavy storage tanks, while cooled fuels require equipment to maintain low temperatures.
Beyond gasoline and diesel, other fuels like compressed propane, ethanol, and methanol offer energy densities per unit volume that are less than gasoline and diesel, and energy densities per unit weight that are less than or equal to that of gasoline. Natural gas, either in liquefied form (LNG) or compressed (CNG), are lighter than gasoline but again have lower densities per unit volume. The same is true for hydrogen fuels, which must be either cooled (down to -253oC) or compressed (to 3,000 to 10,000 psi).
However, considering only energy density leaves out the relative fuel economies associated with vehicles capable of using other fuels. The typical fuel economy of an internal combustion engine in a light-duty vehicle is around 25 miles per gallon. On an equivalent basis, electric vehicles with fuel cells powered by hydrogen can double the fuel economy of a similarly sized gasoline vehicle, while battery-powered electric vehicles can achieve a quadrupling of fuel economy, but the costs of fuel cells, hydrogen storage, and batteries are prohibitively expensive to most consumers and the availability of refueling and charging facilities is extremely limited. In addition, the improvement in fuel economy of these vehicles does not compensate for the lower fuel densities of hydrogen and various battery types like lithium ion, lithium polymer, and nickel-metal hydride batteries that result in limited driving range relative to gasoline-powered vehicles.
Since Diesel is more dense, holds more energy than gasoline in weight, and requires less refining, then why does it cost 10%-15 % more at the pump ?
Is it strictly the amount of Road Taxes ?
“Is it strictly the amount of Road Taxes ?”
No, it was getting the particulates out of the fuel (low sulfur), as in “clean diesel”. They have done that, but it’s adding at least 50 cents per gallon to the cost.
That three little diamonds, just above the 0.00, represent different types of batteries. The one on the right is probably Lithium Ion. So you get an idea of what you’re dealing with. That’s why running the heater on an electric car is a battery-killer, while running the heater on a gas car is free heat (that would have been rejected by the engine or radiator anyway).
Is it strictly the amount of Road Taxes ?
I noticed a "bump" in Diesel prices when refiners introduced the "low sulfur" product. I would imagine that there may be low sulfur (sweet) crude but just like low sulfur coal there isn't enough to satisfy demand. That would lead to additional processing at the refinery to reduce/remove sulfur from the product. Refining crude oil often involves catalytic processing with precious metals like platinum.
Prior to the low sulfur product, Diesel was close to a dollar less than gasoline. Of course both were subject to road taxes. At that time I was heating my house with "heating oil" which was #2 Diesel dyed red to indicate "for off-road use only". My last oil fill was $680 for 168 gallons with out the road tax. That's $4.05 a gallon when gasoline was in the $3 range w/ tax included. I called the jobber and asked "why so high" and he said "special handling". I switched over to natural gas heat, the savings paid for the new boiler in three years.
Take your pick, it could be caused by legitimate processing costs or rapacious greed. Maybe a little of each...
So ethanol is heavier than gasoline, and is more dense according to the graph.
But also ethanol has fewer Btu’s for energy.
So , our $4.00 per gallon ethanol gas would cost us approximately $4.35 as a pure gas ?
The $4.00 per gallon ethanol gas doesn’t include government subsidy to the ethanol industry .
Personaly, I would rather have corn for feed and nutrition of humans and domestic annimals during a drought,
rather than the intransigent EPA trying to get 15% ethanol gas usage during a drought.
That’s it, Im getting me a coal powered car!
“So , our $4.00 per gallon ethanol gas would cost us approximately $4.35 as a pure gas ?”
Actually, no. Look again...more like $6.00. There simply is not as much energy in ethanol (that’s why drunks pass out). You are right, there is NO REASON to keep trying to use ethanol for fuel. With fracking, we have what we need and will have more and more of it. Use the corn to feed the animals...rather than having to kill them early (i.e., I like cows).
The simple refining ended with the EPA ultra low sulfur diesel requirements. Even the most sweet crude requires hydro treater and the like. Simple cut of the topping plant cannot be sold in the US.
So my visions of a coal powered mobile electric car recharging tow vehicle may actually be more efficient than a diesel version?
Also I forgot to include you get more BTUs, more energy per gallon with diesel so it helps justify the price. You can travel the same miles for less gallons with diesel over gasoline.
The ethanol subsidy ended a little over a year ago. The mandate to use remains.
Why shouldn’t you pay more for more btus?
Forger the electricity, use your coal to generate steam!
Of course, steam for the turbine generator so we can charge the helpless, stranded electric cars and their owners as we tow them on to their destination. This thing would look like part locomotive part motor home and part car carrier. With free WiFi even.
My buddy’s daughter put down 5 grand on a Tesla SUV that won’t even be manufactured until 2014. That boy Elon Musk(rat) is one hell of a salesman.
Oh I almost forgot, my son recommended a steam whistle and a cow catcher.
Egads, I wonder if she is interested in some investment property in the everglades.
Diesel used to always be cheaper than gasoline, it wasn't until the mandatory ultra-low sulfur regulations that it became more expensive. I, personally, believe that the reason the price has not gone down (as their filtering has been paid for) is because it's now "normalized" as more expensive [in minds] than gasoline...
That said, if they were to increase the price of diesel-fuel by a dollar, I'm fairly sure our domestic shipping industry would collapse. -- and just imagine the ways they could "never let a crisis go to waste" if that were to happen.
The Ultra Low Sulfur Diesel requires a heck of a lot more than a filter. Just like reformers are run for every gallon of modern gasoline, you won't get ULSD without running product through hydrotreaters and similar process equipment.
Ah, I see.
I still think that ULSD is a bad idea.