ethanol is cleaner, but it has a lower mpg, is it still cleaner than gasoline per mile?

Question

per mile which is the cleanest in general? , gasoline,
clean disel,ethanol or biodiesel?

per mile which is the cleanest refering to carbon dioxide? gasoline, clean diesel, ethanol, or biodiesel?

Answer 1

The short answer - ethanol is far cleaner than gasoline or diesel more than making up for the lower mpg you get with ethanol.

There are several of types of pollution that are formed when a fuel is burned. The four most important are CO2, Nitrogen oxides, SO2 and particulates. Actually unburned fuel can be and issue too.

SO2 is only formed if the fuel has a high sulfur content which is the case with many diesel fuels. It is not a problem for either ethanol or gasoline. Like SO2 particulates are a problem primarily for diesel engines and not gasoline or ethanol. Diesel engines are not generally as clean burning as gasoline engines for this reason. If the fuel is carefully refined the sulfur can be removed. Also the engine can be designed to remove nearly all of the particles (clean diesel technology) but this is not currently done in the United States. Bio diesel avoids the sulfur problem but might still have the particulate problem, I'm not sure.

Nitrogen oxides form due to high combustion temperatures and depend upon the type of fuel. Ethanol forms very little nitrogen oxides and is actually added to gasoline to reduce their formation so ethanol is far cleaner in this regard. Diesel engines form nitrogen oxides as well. Catalitic converters perform two functions they reduce nitrogen oxides and they oxidize unburned fuel in the exaust.

While all these fuels produce CO2, it is a pollutant only if the fuel contributes to the total CO2 concentration. As others have noted a fuel derived from a fossil source contributes CO2 wheras a fuel derived from a biological source does not. Bio fuels do not contribute to total CO2 because the plant removes CO2 from the atmosphere when it grows and then the same CO2 is released back into the atmosphere when the fuel is burned resulting in no net change. However there will be some fossil fuels used in the growing and manufacture of ethanol and this will result in some contribution of CO2.

As others have noted one issue with ethanol production is the net energy yield. Recent studies have found that net energy yield for ethanol produced from corn is about 1.2X. Net energy for ethanol produced using a cellulose feedstock is on the order of 7-8X. These figures are for net energy and so the lower mileage of ethanol is accounted for. This means corn based ethanol is just barely worth doing from an energy production point of view. Cellulosic ethanol on the other hand is very favorable from an energy production point of view.

It is worth pointing out that ethanol use may make sense for other reasons than producing energy. For instance reducing nitrogen oxide production when blended with gasoline.

Answer 2

Ethanol would run poorly in cold temperatures.

In the USA, it's production would probably cost the same as gasoline. When gas is $5 per gallon, then MAYBE, Ethanol will be a bit cheaper.
(In Brazil, where Ethanol is used more widely, it is cheaper because of cheaper labor costs).

Here is the MATH on carbon dioxide. If you deliberately GROW and make ethanol, you will be contributing to the carbon dioxide totals. If you pump crude oil from the grown, you contribute to the carbon dioxide totals.

If you burned RUBBISH and other consumables that would otherwise ROT, the carbon dioxide totals would be the same either way.

SOLAR energy collection IS a positive way to get energy without contributing carbon dioxide. This could be WIND, Solar collectors, Tides, Hydro-electric... all sources that are generated from sun-power.

Hybrid cars would be much better if recharged by solar energy forms.

Solar energy could be stored in the form of Hydrogen. Then the hydrogen could be burned, yeilding only water as a byproduct. No green house gas would be produced.

Answer 3

Depends on what you mean by "cleaner". Reserving the discussion to carbon dioxide, which is everybody's bogey man these days, we can say this: A fuel produced by biological means has a net effect of zero on carbon dioxide, as all the carbon in the fuel was once part of, and will again be part of, plants. Petroleum based fuels will have a net contribution to CO2 of approximately three times the weight of the fuel.
There are two important facts that should be kept in mind when considering this:
- Most of the world's carbon dioxide is dissolved in the ocean. The atmosphere contains approximately 2,875 billion metric tons of carbon dioxide. The ocean contains 144,700 billion metric tons -- fifty times as much. Clearly, the equilibrium between oceanic and atmospheric CO2 is of crucial importance.
- Biological fuels require considerable energy to produce. In many cases, the energy consumed exceeds the energy produced. Even a tie may lose: if it takes a gallon of gasoline to make a gallon of alcohol, you have a net loss: the gasoline has 120,000 BTU per gallon, while the alcohol has only 85,000 BTU per gallon.

Answer 4

In principle, all these fuels can be burned to give nothing but CO2 and water. But in practice it's easier to burn ethanol cleanly than any of the others. Methanol is clean burning too.

Answer 5

work closer to home, ride a bike instead of driving, use public transportation