As we go to press with this newsletter the national average gas price for regular unleaded gasoline is $2.85 per gallon, down from a high of $4.12 in July. Crude oil hit its record of $147.27 per barrel in July as well, a price that will not only be reflected in gas prices but price increases in food, plastics, medicines, and virtually every product we currently take for granted. As we begin acknowledging the skyrocketing costs of energy to our pocketbooks and environment, people and governments are groping for alternatives to petroleum. While many people think these alternatives require new cutting-edge technology, one has been around for the past 4000 years.
Ethanol, or alcohol, seems like an ideal replacement for gasoline. It has similar energy storage to gasoline, burns with almost no carbon or pollutants, and is inexpensive relative to oil. It is renewable, and can be produced by individuals, co-ops, or small companies in local settings. Not so with gas or oil.
There are two types of alcohol, ethanol and methanol. Ethanol is made when yeast ferment sugars or starches, and is the alcohol in whiskey, wine, and beer. Methanol comes from the fermentation of rougher cellulose plant materials like grasses or wood. It is in rubbing alcohol, and it’s deadly. Although ethanol and methanol are both used as fuel, methanol has low energy storage compared to ethanol. It is corrosive and can cause damage to engine components, but could be replaced by ethanol in most applications. Methanol’s major advantage is that it can be made from any almost any plant matter, so it allows for recycling of things like hay, weeds, or corn stalks that might otherwise be thrown away. Work is being done on breaking down the cellulosic feedstocks that produce methanol into the sugars and starches necessary for ethanol, but it’s not commercially practical yet.
The major critique of alcohol is that it can be energy negative, meaning it can cost more than a gallon’s worth of energy to produce a gallon of alcohol. One analysis does indeed indicate ethanol is negative but most other studies show that it is positive, in some studies by as much as eight-to-one. If mixed biomass is used instead of a single feedstock, the differential could be positive by a ratio of hundreds to one. The real positive/negative ratio depends on what energy is included in the production of the alcohol and what type of feedstock is used to produce it.
The first issue is the things that are included in the energy costs of the product. For example, if corn is used as a feedstock then the cost of production obviously includes land, labor, seed, fertilizer, and water. It also includes the cost of the equipment to farm the corn, the cost of the fuel to run the equipment, and the cost and time of distilling and packaging the alcohol. But what about the opportunity costs of using the corn as feedstock instead of food? What about the cost of distributing the alcohol to the users? When you consider the alternative of gasoline, does its production cost include the cost of the refineries? Does it include the cost, in blood and treasure, of the military used to defend the oil supplies? Are the environmental costs included in the production of either alcohol or gasoline? As you can see the costs of producing any fuel can be very arbitrary, so it pays to take a close look at the processes used to calculate cost in any of these studies.
The second issue is that the type of feedstock determines how much alcohol can be produced. Corn is frequently referenced as a feedstock because our country produces such a large surplus, but it takes a huge amount of water and resources to produce corn even though it has a low alcohol yield compared to other feedstocks. Corn, at 200 gallons of ethanol per acre, is at the low end of the scale near figs (30 gal), wheat (79 gal) and apples (140 gal). Sugar beets (400 gal) and even prickly pear cactus (500 gal) are more efficient feedstocks than corn. The high end of the yield scale includes beets (940 gal), sweet sorghum (1100 gal), and palms (2140 gal). The highest yield crop is the humble cattail. Managed as a single crop and fermenting only the starches, cattails can yield up to 2,500 gallons per acre. If they are grown in sewage and the cellulose material is fermented along with the starch they can yield an amazing 10,000 gallons of alcohol per acre or more, 50 times the yield of corn.
Finally, there are environmental advantages to ethanol that aren’t included in the calculation of its energy costs. Petroleum is an open-loop fuel when it comes to carbon production, while ethanol is closed-loop. This means that the carbon in petroleum was stored safely underground millions of years ago but it is released when the petroleum is dug up and used. Ethanol locks carbon into the soil and roots of the feedstock, so it is never released to become a greenhouse gas. It has no emissions at all from combustion, minimal emissions from feedstock farming or distilling, and no possibility of an oil spill to destroy oceans or coastlines.
We know our energy future can’t depend on the oil companies, so we can’t let the oil companies tell us what it will depend on. Ethanol made from corn doesn’t make sense, but unless you’re a lobbyist from Iowa or an oil company executive trying to sink the whole idea, there’s no need to make it out of corn. As our energy debate continues, let’s remember that just because ethanol has always come from corn doesn’t mean that it the best way, or even a good way, to make it in the future.
