10 Disadvantages of Biofuels

This one relates to the little multicolored maps on the backs of seed packets. The ragged stripes stretching from east to west are growing zones: regions where water supply, temperature and sunlight make hospitable climates for certain types of plants. If you live in Zone 5, for example, you will likely have trouble growing a plant that requires the long growing season and high heat of Zone 10 [source: Burpee].

Biofuel crops are no different from petunias or peppers in this regard. Certain crops will grow better in certain regions and may not grow at all in others. And while the range of oil-producing crops considered viable for biofuel production is wide enough to fit most growing zones, the most productive crops simply won't grow everywhere. Consumers living in a low-producing region would need to have biofuel trucked or piped to them, increasing both cost and the amount of emissions produced in production and transport [source: Pimentel].

Researchers are working to increase biofuel yields from weather-tolerant crops [source: Lau]. But in much the same way that oranges will never be a cash crop in Alaska, there will always be some regions that simply can't support large-scale production of biofuel-rich crops.

Ask any grade-school student what a plant needs to grow, and he or she will likely mention two things: https://science.howstuffworks.com/sun.htm

sunlight and water. While the first is a bit beyond the control of biofuel producers, the second is at the core of a potentially serious drawback of plant-based fuels: The water demands of some biofuel-producing crops could put unsustainable pressure on local water resources if not managed wisely.

A 2009 study suggests that, in the rush to produce enough corn-based ethanol to meet federal alternative energy requirements, biofuel demand is already putting stress on fresh water supplies in the Great Plains and central Southwest [source: McKenna]. Central to the problem is corn's relatively high water requirement. Researchers are investigating ways to genetically engineer less thirsty crops, and carefully planning what biofuel crops to plant in a given region can mitigate this problem [source: Lau]. But large-scale biofuel production -- especially using corn, and in arid parts of the world -- will have to share finite water resources with drinking and irrigation needs.

Biofuel production using food crops such as corn, soybeans and sorghum has the potential to alter drastically the world's access to affordable food. The simple supply-and-demand economics of biofuels -- increase demand for corn, for example, and corn becomes more expensive -- can pose a threat to some regions' food security, or the access to affordable nutritious food for the region's population [source: Naylor].

The rise in demand for food-biofuel crops can have a positive effect for crop producers, in the form of higher prices for their produce. But that price quickly trickles down to consumers. A pig farmer, for example, may have to pay a few extra dollars per bushel to buy corn to feed his livestock. That directly translates into more expensive bacon and ham at the grocery store [source: Carey]. For the billions of people who live on only a few dollars per day, even a small increase in food prices could put their access to proper nutrition at risk.

One way to counter this lies in simple diplomacy: The globalization of world commerce means that it's now easier than ever to move food supplies from one part of the world to another in response to increased demand. However, ready access to food imports, and the ease of exporting, hinge on a wide range of political and social factors. Relying on produce from halfway around the globe to feed a hungry nation is a risky price to pay for widespread biofuel integration into the world's energy supplies.

It seemed like a win-win idea: European demand for biofuel was set to spike, driven in part by regulations aimed at reducing greenhouse gas emissions. Industry researchers had found an answer in palm oil, a relatively easy-to-produce biofuel source. Plantation owners prepared their operations to meet the demand …

… and environmental chaos ensued. According to some estimates, expansion by Indonesian palm oil plantations caused the vast majority of that nation's deforestation in the late '80s and '90s. And high-consumption production practices -- moving palm oil with petroleum-powered trucks and the practice of draining and burning peat bogs to prepare farmland -- have made the southeast Asian nation one of the world's leading greenhouse gas emitters [source: Rosenthal].

The Indonesian palm oil problem is really a combination of biofuel's drawbacks. The regional nature of high-producing plants such as palm oil means that certain parts of the world are agricultural gold mines: Biofuel demand motivates plantations to expand quickly. But if not done with an eye toward conserving resources and maintaining the spirit of reducing emissions through plant-based fuels, this ramping up of production can lead to greater environmental problems than the ones it's meant to solve.

This is a problem biofuel crops share with food crops, gardens and lawns worldwide. All of these plants grow better when given fertilizer. But those fertilizers can have harmful effects on the surrounding environment, and expanded biofuel production could mean a major pollution threat to sources of fresh water.

Many fertilizers contain nitrogen and phosphorus. While both of these additives promote rapid and hearty growth in many crops, they have a downside. Overuse or inappropriate application can leave excess fertilizer in the soil, which then washes through regional watersheds and into streams, rivers, lakes and underground aquifers. And once the chemicals are in the water supply, bad things can happen.

Phosphorus has been implicated as a trigger of localized algae blooms: The tiny aquatic plants feed off it and rapidly reproduce, often killing other plants and aquatic animals by reducing the amount of oxygen in water or by releasing toxic chemicals. Nitrogen in drinking water can lead to a host of health problems, including methemoglobinemia, a condition that prevents infants from utilizing the oxygen in their blood [source: Rosen and Horgan]. Careful fertilizer application can help prevent widespread pollution problems, but expanding biofuel production to meet the world's demand opens the door for more mistakes in this realm.

It might seem counterintuitive at first, but some scientists argue that widespread biofuel production is a negative-sum game: Producing enough biodiesel or ethanol to replace one gallon of petroleum fuel, they argue, requires the energy equivalent to several gallons' worth of petroleum fuel [source: Pimentel].

To put it another way, think about a field of corn being grown for ethanol. It may produce 100 gallons of the fuel out of one season's crop. But if the tractors that tend the field burn 75 gallons of fuel in the season, the truck to transport the corn to a processor burns 20 gallons on the trip, and the processor uses the energy of 40 gallons of fuel to run its distillation equipment, is the ethanol produced really an environmentally friendly, low-emission fuel? Add other resource costs into the equation, such as the gallons of fresh water needed to grow the plants and the amount of fertilizer needed to keep them healthy, and it becomes even harder to equate biofuel with real energy and carbon emission savings.

A 2005 study suggested that, using current farming and production technology, it takes anywhere from 27 to 118 percent more energy to produce a gallon of biodiesel than the energy it contains [source: Pimentel]. While technology may eventually narrow those ratios, the input-output energy ratio of modern biofuel production is a major drawback to its widespread use.

Many biofuel crops are used to make biodiesel. The oil in their seeds is pressed out, filtered and converted to fuel using a chemical process. But while different crops can become biodiesel through the same process, the resulting fuel can vary greatly in its ability to produce power. In other words, not all biofuel crops are created equal.

First, there's the issue of yield. The amount of vegetable oil available in an acre of crops can vary widely, from 18 gallons per acre for corn to 635 gallons for oil palm [source: Journey to Forever]. And again, not every climate region is suitable for a high-yield crop that could produce economically viable biodiesel [source: Burpee].

Second, the oil these plants produce is not equal. Think about the oils in your kitchen: While the olive oil in the cupboard is easy to pour, the lard and vegetable shortening have a paste-like consistency. These differences in state at a given temperature come from the oils' molecular makeup. The molecular bonds in oils low in saturated fats, which stay liquid at lower temperatures, vary from those high in saturated fats, which often form solids in average temperature ranges.

This difference has an effect on the oils' viability as fuel. One obvious consideration is the gel, or clouding, point: A fuel that turns solid well above water's freezing point would not be very useful in a cold location. Consequently, it makes sense to look for an unsaturated oil as a biofuel source.

But there's another complication that arises with this selection. Many unsaturated oils have undesirable burn characteristics: They'll leave gummy residue in an engine when used as fuel. Hydrogenating, or treating the oil with hydrogen, can mitigate this problem, but increased processing means increased cost [source: Journey to Forever].

The symbols of agricultural success in many parts of the world are endless fields of corn, soybeans or wheat, with identical crops stretching as far as the eye can see. Unfortunately, that image is also a sign of monoculture, an agricultural problem that could conceivably get much worse due to biofuels.

Monoculture refers to the practice of growing one heavily concentrated crop, rather than the rotation of various crops through a farmer's fields over time. While this is an economically attractive practice, playing off economies of scale to make the crop more profitable for the farmer, it can have severe environmental drawbacks. Hundreds -- even thousands -- of unbroken acres of one crop offer an irresistible target for plant pests; pest populations can explode beyond control in such a tempting environment. Likewise, the nutrients that are put back into the soil through crop rotation and allowing fields to lay fallow disappear under intense monocultural farming. Long-time monoculture farms have to use much more artificial fertilizer than their more sustainable peers, increasing water pollution. And the singular nature of a monoculture crop increases the risk of a total loss for the farmer; imagine the damage if a severe strain of corn blight hit an ethanol-producing corn farm [source: Altieri].

Monoculture isn't a problem confined to biofuel production; it's an issue that had been studied for years in relation to large-scale food crop production. But since many popular biofuel crops, such as corn and soybeans, are also popular food sources for much of the world, it stands to reason that the problems related to monoculture could get much worse as consumers demand more biofuel.

Farmers of corn, soybeans and cotton -- all potential biofuel sources -- are increasingly planting genetically modified versions of those plants [source: United States Department of Agriculture]. This isn't the selective breeding that farmers have practiced for years; genetically modified crops are altered in the lab to tolerate herbicides better, fight off pests or produce higher yields.

In theory, this sounds like a terrific way to keep up with biofuel crop demand. After all, a better harvest would reduce prices and ensure there's enough corn or soybeans on hand to feed and fuel the world, right? But in cases that seem as much science fiction as they are scientific fact, genetically modified crops have accidentally developed unintended -- and sometimes dangerous -- traits.

A prime example of this occurred in the early 2000s. During initial tests of a modified strain of corn, researchers discovered that the crop, which had been engineered to fight off a moth known to prey on corn, produced pollen that could possibly kill larvae of the monarch butterfly. Scientists sounded the alarm, and further tests by academic and industry researchers confirmed that the corn's pollen posed a threat to monarchs. By that time, the corn had been on the market for a season. Thankfully, it didn't sell well, so few fields were planted with it. Had it been the season's popular strain of corn, there could have been an ecological disaster as monarchs migrated through the corn-heavy American Midwest [source: Mellon and Rissler].

Perhaps the most straightforward of biofuel's drawbacks is the most obvious: It isn't petroleum-based fuel, so it will operate differently in engines designed for petroleum-based fuel.

Corn-based ethanol, for example, has a higher density than gasoline; fuel injectors have to be larger in an ethanol-only engine to match the fuel flow of a comparable gasoline engine. And alcohol fuels (including ethanol) can corrode or damage some of the metal and rubber fittings used in gasoline-powered engines. The conversion from one fuel to the other, in some cases, requires a range of new injectors, gaskets and fuel lines. And once the engine's running, the differences in combustion properties between gasoline and ethanol means that the ethanol-converted engine needs to have its ignition timing adjusted to operate properly [source: Tsuneishi].

Biodiesel doesn't fare much better. Because of the higher-than-petroleum gel point of many biodiesel-producing oils, a biodiesel engine can be difficult -- if not impossible -- to start in cold weather. The problem is even worse for pure vegetable oil, used as fuel in so-called "greasecars." Drivers of vehicles using these fuels often have heating units installed to keep the fuel tank and lines free from gelled fuel, or install dual-fuel systems that flush the engine with petroleum diesel on start-up and shut-down. A number of manufacturers sell components for biodiesel and greasecar conversions, and intrepid tinkerers often find ways to overcome the gelling problem. But the conversions add time and money to the biofuel equation, something that can be off-putting for potential biofuel users.

To learn more about biofuels, click to the next page.