Biodiesel:An Alternative Fuel With a Foothold

Seeing the effect we’ve had on the world through industry—in particular, the burning of fossil fuels—can be depressing. With the world’s temperature increasing faster than it has in millennia, and our continued, voracious consumption of our rapidly depleting fossil fuels aiding that rise, despair seems the natural recourse. Nonetheless, countermeasures exist, and to my surprise one of them—the use of biodiesels as a fuel source—is gaining traction.

Global warming, the facts of which I described in my first installment of “The Case For GlobalWarming,” is largely a consequence of our fossil fuel use. While I go into more detail on how human civilization creates this warming effect in next week’s installment, the basic principle is simple: burning fuels for heat and energy, such as gasoline, release greenhouse gasses into the atmosphere. They’re called “greenhouse gasses” because they contribute to the greenhouse effect, whereby, as in a greenhouse, they allow sunlight to enter the atmosphere but trap the reflected heat inside said atmosphere. Our burning of coal, petroleum and other products pumps more of these gasses into the air, wrapping the planet in a thickening blanket of methane, carbon dioxide, and other pollutants.

Carbon dioxide, of course, amounts for most of the greenhouse gasses we emit, and in the United States, fuel used for cars and trucks is the second largest contributor to our carbon footprint. Carbon dioxide results from burning just about anything with carbon in it, and the fossil fuels we use produce a sizable amount. It should come as no surprise, given that petroleum comprises the liquefied corpses of primeval microbes; and microbes—as with all life—consist of carbon compounds.

Not all carbon compounds, though, produce the same amount of carbon dioxide when burned. Diesel fuel, for example, releases less CO₂ when burned than gasoline, despite both being crude oil derivatives. (Diesel, however, releases more particulates, which could make it a worse contributor global warming.) Biodiesels emit even less.

Biodiesels are a variety of synthetic diesels made not from crude oil, but alcohols and fatty acids. These fats could be vegetable oils, greases or lard, obtained either as by-products of food production or from crops raised for energy purposes. The resulting substances chemically resemble petroleum-based diesel fuel, but have distinctive properties. One of these is that biodiesels burn more cleanly than regular diesels. Burning biodiesel produces on the order of 78% less carbon dioxide, and produces less of most other pollutants as well.

EPA chart comparing emissions of diesel/biodiesel solutions.
Chart found at the Alternative Fuels Data Center, US Department of Energy

The above graph demonstrates, on a relative scale, how different diesel/biodiesel solutions compare with respect to greenhouse gas emissions. On the far left we have a 100% petroleum diesel solution, and on the far right a 100% biodiesel solution. The emissions of carbon monoxide (CO), particulates (PM), and unburned hydrocarbons (HC) drops substantially in solutions with more biodiesels, with the only downside being an increase of 10% in the emissions of nitrous oxides (NOx) compared to pure diesel. Given recent studies that diesel's particulate emissions could dwarf its carbon advantage with respect to gasoline, the reduction in particulate emissions in biodiesels are especially encouraging.

Since nitrous oxides can have a deleterious effect on the environment and human health as well, we cannot ignore this factor. However, the reductions in carbon monoxide emissions (which itself is a toxic gas), as well as other by-products, dwarf this increase. Also, biodiesel releases almost no sulfur compounds when it burns, unlike ordinary diesel. (Just the Basics: Biodiesel, pg 2) Moreover, biodiesel itself is non-toxic. If a truck of biodiesel were to spill, it would have far less impact on the environment compared to the disastrous consequences of spilling oil, regular diesel or gasoline. (Alternative Fuels Data Center, 2013)

Given the numerous benefits of biodiesels, why haven’t we switched over to this wonder fuel already? The fact of the matter is that we already have partially switched to biodiesels. While diesel is not used so much outside of large trucks and commercial vehicles in the United States, the fuel does appear to be gaining traction. New EPA fuel standards have led to an increase in domestic production in the States, (Wikipedia, 2013), and U.S. Department of Energy allows you to search for biodiesel stations near you. While not the most numerous, there are more of these stations than you may expect. Furthermore, a 2012 article in Scientific American mentions a return of diesel engines in consumer vehicles, with a focus on attempts by GM. Since diesel cars use less fuel per gallon than gasoline cars, they promise to be far less expensive at the pump. This may pave the way for a consumer market for biodiesels.

Nonetheless, barriers remain to the widespread adoption of biodiesels, and there remain disadvantages to using them. Many of today's diesel vehicles can run on biodiesel with no modification, but not all of them do. Furthermore, most diesel engines aren't rated for pure biodiesel. Typically, the fuel has to be a solution of diesel and biodiesel—with far more diesel than biodiesel. Use of a pure solution, or of a solution with too much biodiesel, could void the manufacturer's warranty. (See Diesel Vehicles Using Biodiesel, Alternative Fuels Data Center) Moreover, as biodiesel tends to crystallize in lower temperatures, it does not provide a suitable option for cold weather conditions. The Department of Energy considers a 20% biodiesel solution to provide the optimal balance of cold weather performance, hardware compatibility, and emissions reduction. (See Benefits and Considerations, Alternative Fuels Data Center)

Needless to say, these operational factors substantially reduce the ecological benefit to the use of biodiesels. However, even if we could quickly switch to a pure biodiesel fuel economy, it could not provide a total solution. There are two major reasons for this fact. The first is that we would have difficulty producing enough biodiesel to meet current demand. We do not have enough oils from by-products to meet demand, and growing crops specifically to be used as fuel can be economically and environmentally harmful. (Wikipedia, 2013) Smaller and less developed countries, which have an economic incentive to produce and export valuable biofuels, risk famine if too many farmers switch to non-food crops for biofuel export. (Wikipedia, 2013)

Moreover, the amount of land required to meet present demand may require clearing more forests to make way for biofuel farms. (Wikipedia, 2013) Such deforestation not only destroys the habitats of thousands of plant and animal species, but can contribute to global warming. As plant life inhales CO₂ and exhales oxygen, slashing forests slows the rate at which carbon dioxide is filtered from the atmosphere, increasing the amount present in the air and accelerating the greenhouse effect. While biodiesels may pump less CO₂ into the atmosphere when burned, the clearing of forests required to create that fuel could have a worse environmental impact than just using fossil fuels.

The second factor, of course, is that biodiesels still release carbon dioxide into the atmosphere in the first place. Far less than present fuels, yes—but it still produces greenhouse gasses. On a large enough scale, that still presents a problem. If we want to arrest or reverse global warming, we will need to make sure that more carbon is going out of the atmosphere than going into it. That could mean that the reductions from the use of biofuels might not be enough, even in principle. Biofuels can only ever be a stopgap measure: other solutions will have to sustain us for the longer term.

Nonetheless, fewer emissions remains a better option than more. It could be that some of biodiesel’s disadvantages may be offset by clever engineering and more research. If consumer biodiesel becomes a reality, I could see hybrid cars using biodiesel engines to reduce their emissions even further. Provided we continue working on other solutions for the long term, adopting biofuels may keep us afloat until even cleaner technology becomes a reality.