Biofuels and biofuel crops have long been in use as a substitute for fossil fuels. Biofuel is a low-carbon fuel that is produced from biomass, rather than by the very slow geological processes involved in the formation of fossil fuels. The demand for biofuels is expected to double in the next few years, and could potentially allow us to decrease our dependence on fossil fuels.
Also known as energy crops, biofuels include things like wheat, corn, soybean, and sugarcane, but can also be made using waste materials. Biofuels burn cleaner than fossil fuels, and release fewer pollutants and greenhouse gases, such as carbon dioxide, into the atmosphere.
They are relatively sustainable and energy companies sometimes also mix them with gasoline. Unlike oil, coal, or natural gas, biofuel sources, in theory at least, are renewable.
Biofuels generally fall into two categories, bio alcohol, and biodiesel. The former, such as ethanol, is created through fermentation, using yeast and bacteria to break down starches and sugars from corn and other plants. Scientists are also working to develop technologies that would allow bio alcohol to be made instead of cellulose and hemicellulose, the non-edible fibrous material that makes up the bulk of plant matter. In fact, several commercial-scale cellulosic ethanol biorefineries are already in operation.
Biodiesel, on the other hand, is created in refineries that use new and used vegetable oils and animal fats such as recycled cooking grease. These oils are then treated with alcohol and converted to biodiesel.
As you can imagine, there are some drawbacks to these kinds of fuels. Issues include the amount of land and resources (such as water and fertilizer) required to grow the crops and the use of food crops as fuel. This, in particular, creates problems with higher food prices and deforestation. The latter being somewhat counter-productive to the aim. Additionally, the costs for converting food crops into energy, as well as the need to retrofit existing vehicles and power plants to run on them, are not cheap.
All of that being said, let's take a look at some of the most important biofuel crops. This list is not exhaustive and is in no particular order.
1. Corn is a great biofuel source
Corn is generally considered the king of ethanol-based biofuels. Sugar-rich corn is turned into ethanol in a similar fashion to beer brewing. The kernels are ground up and mixed with warm water and yeast. The yeast ferments the mixture to produce ethanol. This ethanol is then blended with gasoline to use in existing car engines. Pretty neat!
This mixture releases less carbon monoxide, nitrogen oxide, and sulfur than run-of-the-mill gasoline and reduces smog in cities. The reason the kernels alone are used is that the main body of the plant contains cellulose, which is more difficult and expensive to break down.
2. Another biofuel example is rapeseed/canola
Rapeseed oil has been used to cook food and in lamps for centuries. Today, it's an important biodiesel source. The most important type is canola because, compared to other rapeseeds, it is low in erucic acid, which makes it healthier for animals and humans to eat.
It's an interesting fact that biodiesels tend not to fare well in cold climates. This is because vegetable oils tend to be high in saturated fats, which allow ice crystals to form at low temperatures. This is obviously not good for combustion engines.
Canola just so happens to be low in saturated fats, which clearly gives it an advantage in colder environments than its alternatives. Rapeseeds are also relatively high in oil content when compared to most plants, which makes them great crops for making fuels.
3. Sugarcane is a commercialized biofuel
Brazil has been working tirelessly to reduce its dependence on fossil fuels over the years. This South American country has been growing energy crops since the 1970s as a direct consequence of the Middle East Oil Embargo. When oil prices leaped, the Brazilian government encouraged its farmers to plant sugarcane.
Sugarcane is used to produce bioethanol, not unlike corn. Brazil has invested billions of dollars into this industry, to such an extent that it is now cheaper than gasoline. Interestingly, in the 1980s, most cars in Brazil were ethanol-powered, but today most utilize flexible fuel engines. Producing ethanol from sugarcane is six times cheaper than using corn. However, farmers burn their fields during sugarcane harvesting, releasing massive amounts of greenhouse gases into the atmosphere and somewhat negating the carbon benefits from using bioethanol.
4. Palm oil is one important biofuel example
Palm oil is extracted from the fruit of palm trees and it is one of the more energy-efficient biodiesel fuels on the market. Diesel engines also do not need to be converted to run on palm oil either.
Palm oil biodiesel is less polluting than gasoline as well. Palm oil has helped develop the economies of Malaysia and Indonesia in particular. However, the growing of palm trees for biodiesel in these countries has led to the burning of thousands of acres of rainforest each day for land to grow the crops. This destruction threatens the fragile ecosystem and endangers thousands of plant and animal species.
5. Jatropha is probably a biofuel you've never heard of
This ugly, poisonous weed is a big player in the biofuel market. The bushes grow quickly, do not require a large amount of water, and their seeds have around 40% oil content.
India is currently the world's largest Jatropha producer and their biodiesel industry is centered on this crop. This has allowed the country to bring economic benefits to rural farmers who can grow this crop on agricultural land too poor for other crops. Jatropha plants can live for 50 years and do very well on land devasted by drought and pests.
The seeds of the plant are crushed to release the oil for biodiesel production. But the seed cases and vegetable matter are not wasted. Handily, they can also be used as biomass fuel!
While promising, this potential biofuel source has not really been exploited to its full potential.
6. Soybean plants are valuable biofuel crops
Not just used for tofu, sauce, crayons, and shampoos, soybeans can also be used as a fuel source. Most biodiesel in the USA is, as it turns out, made from soybeans. Motor vehicles, heavy equipment, and even buses can run on pure soybean biodiesel or by blending the soy biodiesel with more traditional diesel fuels. The National Academy of Sciences states that soybean diesel yields more energy than corn ethanol.
One bushel of soybeans can yield 5.68 liters (about 1.5 gallons) of biodiesel. However, while soybeans have an oil content of around 20%, other fuels, like Canola and sunflower seeds, have double that, at 40% and 43% respectively.
7. Last but not least: Switchgrass
This plant has the greatest potential to cure our addiction to the use of fossil fuels. Unlike corn, switchgrass has a form of cellulose that uses less energy to convert to ethanol than from processing fossil fuels.
Switchgrass's cellulose ethanol contains more energy than corn ethanol. Although there are not currently large plantations of this crop scientists are currently working on methods to exploit this plant in the future.
Researchers at the Auburn University in Alabama have grown test plots of the plant to produce 15 tons of biomass per acre. It is believed that each acre of the crop will allow for the production of 4,350 liters of ethanol, every day!
Unlike other biofuel crops, switchgrass grows in poor soil on land not normally used for farming, so no cropland is taken away from food production. And because it is a perennial, farmers only have to plant it once, meaning less work to grow.
And that is your lot for today, biofuel fans. These are but some of the most important biofuels grown and harvested around the planet.
There are also a few emerging crops that could, perhaps, take their place among these venerable examples. But time will tell if commercialization of these potential biofuels is realized.