I don’t know if this is a debate, its an actual question. One of the reasons ethanol isn’t used as a fuel is there is concern that growing and making the ethanol requires more energy than it produces. It produces energy, sure but you need to run farms, mills, factories, etc in order to grow it, produce it, isolate it, and transport it and unlike gasoline ethanol requires more BTUs than it produces (I heard it takes 110,000 BTUs of machinery and technology produce enough ethanol to make 71,000 BTUs).
I honestly don’t know the answer to this question. HOWEVER, even if the production cost of ethanol is higher than the energy gain, that’s hardly a reason not to do it. In an ideal situation, most of the energy that is required to produce ethanol that we do not get from solar will come from wind, hydro or nuclear. Since you reasonably cannot have a 2 ton SUV powered by wind, solar or nuclear(at least right now), ethanol is the next best thing.
So the fact that it takes more energy to produce than it gives might be accurate, but rather meaningless. I’m sure that charcoal briquettes you use for your BBQ take a lot more energy to produce then you ever get out of them, changes nothing though.
In the past I (and others, IIRC) have posted links to technical papers that go through detailed energy balances which show that yes, under the current state of the art there is a net energy gain from using ethanol. It took me about 5 minutes to get this page to load, so I’m not going to search, but I’m certain searching on ethanol and energy will yield at least a few good links.
We generally don’t use charcoal briquettes to power our automobiles.
I would have to imagine in the grand scheme of things that charcoal briquette energy efficiency is trivial vis á vis the energy efficiency of motor fuels.
Ok, I’ll take that. What I was trying to say that very few things produce a net energy gain, and just because it is ineffcient does not make it useless. I’m certain that batteries take more energy to produce than they yield, we still use them because they are portable. It’s not really expected to get more than 100% efficiency out of anything, the best we can hope for is to harness energy that is already there (solar, nuclear, wind) to barely push us over that edge. Ethanol gives us portability and space efficiency, if worst comes to worst we’ll still use it even if it takes 10x the energy to produce.
As I understand it, a major con of using ethanol is its tendency to attack rubber gaskets and other assorted parts in engines that haven’t been modified to resist such damage (as opposed to its efficiency).
Indeed, there are very few energy sources that can give you a net energy return, i.e. a source that gives you more energy than what you expend getting it. We call these special energy sources fuels. It’s important to know what these are, because only fuels are viable as a commodity for large scale energy distribution. Examples of fuels include coal, oil, and natural gas. An energy vessel, by contrast, is the opposite… an energy vessel is an energy source wherein more energy is expended getting the source than what you get out of it. Examples of energy vessels include batteries and liquid hydrogen. An energy vessel cannot be used for large scale energy distribution; only fuels can be used for that purpose.
There is debate on whether some energy sources are fuels or energy vessels. Examples include PV arrays and alcohol.
I don’t know the answer to the OP’s question. But my gut instinct is that alcohol is not a fuel - it’s an energy vessel. I say this for two reasons:
A lot of diesel fuel must be burned to make alcohol. Let’s say a farmer must put 10 gallons of diesel fuel into his tractor to pull enough corn to make 4 gallons of alcohol. Would that make sense from a large-scale energy standpoint? Would we conclude alcohol is “clean burning”? The answer is “No.” to both. (Yea, yea, I know energy density must also be taken into account. I’m just trying to keep it simple.) Not to mention that a lot of energy must be expended to till the land, sow the seed, convert it to alcohol, etc.
Consider this: we really don’t have to perform an engineering analysis to determine if an energy source is a fuel or energy vessel. The free market will do it for us. If an energy source is bought and sold as a commodity for large scale energy distribution, and commercial companies are making money selling it (and without the help of government subsidies), then it must be a fuel. Is this true for alcohol? No. Alas, I can only conclude alcohol is an energy vessel.
As I understand it, the situation in Brazil is unique. First, Brazil produces a surplus of sugar-they ferment this and disrill the alcohol. Most of the heat to run the distilleries comes from burning the sugarcane waste (bagasse). Second, the main objective was not to save energy, it was to reduce the huge import bill for oil. Finally, most sugarcane production in Brazil uses horse and ox power (and human power too). So we cannot duplicate the Brazilian’s expereince. To my mind, there are better prospects in making methanol (wood alcohol) from natural gas-this synthesis is quite easy. And we have lots of natural gas-Texas is full of the stuff (the TRC just doesn’t want to sell it at depressed prices, so they leave it in the ground).
I also think that we could make other biofuels…like turpentine (C8H10)-its got lots of energy, and we can get it from pine trees.
The problem with this analogy is that it isn’t that simple.
Generally most of the corn we see growing is used as animal feed.
Its grown weather or not some of it is used for other stuff.
Making fuel is probably one of the best economical ways of using it.
Consider this . the plastic bags you recieve most of your store bought goods in are in some cases made of corn.
Also consider the by products from alcohol plants are used for many things. One of the most common is animal feed.
You should also know that there are alcohol plants springing up all over Iowa.
Someone , or should I say lots of people think its a good idea.
While an energy source’s being a fuel (to use your terminology) is likely a necessary condition for selling it to be economically viable, it’s not likely to be a sufficient condition. There are all sorts of reasons why something could be a fuel, and yet not be economically viable. In order to be economically viable, it needs to be competitive with the alternatives, which at the moment have very high energy returns (coal, oil, uranium). If a fuel has a lower energy return or requires much higher labour or capital expenditures, its price may well be uncompetitive and hence the market won’t provide it without subsidies. This won’t mean it’s not a fuel, just that it’s not as cheap a fuel.
There is one other point worth considering. Suppose you live in Niagara Falls or in the shadow of the Hoover or Grand Coulee Dam. You have all the hydroelectric power anyone could ask for, essentially at your fingertips. You still need to be able to run your car on something, and at present electric-car technology is barely viable. You need a movable fuel source.
If there’s a net energy loss to produce ethanol or hydrogen, but that deficit is made up from stationary power sources, and the ethanol or hydrogen is a reclaimable source (burns clean, more can be produced, etc.), then there’s an advantage to using it.
We have a massive surplus of potential energy available: sunlight, dammable rivers, geothermal, tidal, etc. The problem is that they’re all stationary sources, with electricity the only way to transport that energy. Fueling a vehicle, an airplane, etc., takes a movable energy source. If that tractor has enormous batteries instead of gasoline or deisel motor, and is plugged into a high-amperage outlet in the barn when not in use, you can get a net gain of movable energy source from growing ethanol.
I question the premis that we have a “massive” surplus of actually exploitable potential energy, especially “dammable rivers”. This cleanest and most renewable of energy sources has become politically unacceptable.
But, be that as it may, using energy from these sources to power the equipment to raise corn, and then to distill it into alcohol for transport is absurd. Use the electricity directly to produce hydrogen. Far more efficient to produce, and far better energy density.
I don’t think anybody can really get a clear idea about the viability of ethanol as a fuel in the US until the massive corn subsidies are removed. The reason ethanol is being pushed so hard is not because it’s enviromentally friendly or reduces foriegn dependance on oil, but because it increases the demand for corn.
You are quite right about the fact that it is pushed because it increases the demand for corn. However, it is able to push the demand for corn because it is politically winning to push it as it DOES decrease demand for foreign oil.
This topic comes up every now and then. After Cecil’s column, there was much debate, and most people in the debate ripped Cecil for his non-answer. The consensus as I remember it was that the exact energy economics of ethanol were changing all the time as the processes changed, but that best case scenario was that it only provided slightly more total energy to our economy.
But what has been missed in this thread is that ethanol production does not use up large amounts of diesel or gas compared to what it creates. Ethanol production uses up large amounts of coal. We have plenty of coal. Using Ethanol decreases use of foreign oil to power our cars and replaces it with burning a fuel that uses up our plentiful coal reserves.
As far as the environment goes, it is about a wash, with ethanol winning some points and gas winning others. But it does change where the pollution resides. Gasohol burns slightly cleaner than regular gas, helping out large cities, but adds some pollution around coal power plants in the midwest (which then potentially finds its way to large cities in the east.)
So we subsidize ethanol for political reasons because it supports US produced car fuel.
And don’t forget we subsidize oil production at least as much, but just not in as easily trackable format.
The best previous thread on this topic was in response to Cecil’s column; the thread was Ethanol as Fuel. There’s some pretty insightful commentary and information in the thread (some stupid shit, too, but you can gloss over that), so it’s a worthwhile read. I recall a consensus essentially the same as what BoringDad claims, but read the thread for yourselves.
I understand what you’re saying, but I’ve always hated this particular differentiation, because it leads to unsatisfying conclusions. For example, I think you’d probably agree that, under ideal conditions, ethanol can be produced on a net energy gain basis – it would be a fuel, in other words. However, other processes would result in a net energy expenditure – the ethanol would be an energy vessel. So, in this scenario, I could have two gallon jugs of ethanol, one of which is a “fuel,” and one an “energy vessel,” and yet there would be no physical difference between the two.