In plain English, biofuels are liquid fuels directly obtained from biomass—and that’s what sets them apart from other types of renewable sources of energy. The main types of biofuel in use today are ethanol (alcohol) and biodiesel.
Before we look at more complex aspects, which have to do with the chemistry of biofuel energy, let’s tackle the basic questions first:
- What is biofuel? What’s the official definition and what is the functional one?
- What are the pros and cons to biofuels?
- What are the most important biofuels producers at the global level?
Image source: Biotech in Asia
What is biofuel?
The official definition: A biofuel is any energy-producing fuel obtained through the contemporary (as opposed to geological) process of biological carbon fixation. All biofuels are hydrocarbons made by/from a living organism.
It is important to understand that biofuels can also be man-made in labs; they don’t necessarily have to have been made by a living organism. The only essential condition is that the initial material is CO2 fixed, i.e. transformed into a different molecule, by a living organism, and that this occurs quickly, not over long periods of time.
The practical definition: Basically, a biofuel is a hydrocarbon fuel produced from organic material (something that was once alive) – as opposed to non-hydrocarbon fuels like nuclear fission. It also has to have been formed over a short period of time. This means days, weeks, or months, but not millions of years, as is the case with fossil fuels.
What is a fuel? A fuel is any type of substance, formed through fixing a carbon molecule, which is then able to produce energy in a mechanical system. Fuels can take a wide range of forms, from protein, to alcohol, to fat.
What is biological carbon fixation? In the process of carbon fixation, inorganic carbon (such as CO2) is transformed into organic material, i.e. any type of molecule that could be part of an organism that is alive. The word ‘biological’ refers to carbon fixation that happens in living organisms.
The carbon fixation stage in photosynthesis
Image source: BBC
What is biofuel used for?
In short, biofuels can be used to power any mechanism that would otherwise run on conventional fuels. Here’s how biofuels match up with fossil fuels, in terms of energy output:
|Diesel||Biodiesel yields 90% as much energy|
|Gasoline||Ethanol has 50% of its energy content.
Butanol has 80% of the energy content of gasoline.
|Coal||The majority of biofuels can produce at least this much energy. On the upside, they produce a smaller amount of CO2 emissions.|
At the moment, biodiesel covers some 0.15% of the market in North America and 3% of the German market. The total global output is almost 1 billion gallons. Both North and South America prefer bioethanol (the U.S. and Brazil produce 87% of the world’s total output), while Europe prefers biodiesel.
Did you know that…
- biofuels have been around for as long as cars? In the early 20th century, when Henry Ford was still designing his Model T cars, the plan was to run them on ethanol. Similarly, some of the world’s first diesel engines were designed to run on peanut oil. Sadly, the world then discovered crude oil deposits, which made gas and diesel stay cheap for nearly the entire duration of the century. Only when global warming concerns and rising gas prices became a reality did the world turn its attention back to biofuels.
- one of the most popular biofuels in the U.S. is the same kind of substance as your drink at the bar? Ethanol is an alcohol and is just the same substance you can find in your booze. However, the main difference is that the ethanol that gets mixed into most of the U.S.’s gasoline is chemically treated to be undrinkable. It’s made from highly processed corn.
- a lot of countries around the world are already using biofuels? Some of the cars in Brazil already run on pure ethanol, which is used as a fuel of its own, not as an additive to fossil fuels. Also, in Europe, they use diesel-like fuels made from palm oil.
What are biofuels made from?
The short answer: biomass. What is biomass, though?
Biomass is organic matter, i.e. any dead matter that comes from an organism which was once alive. In practice, this includes:
- corn kernels,
- algae mats,
- sugar cane stalks,
- the cellulosic part of plants,
- coffee beans,
And there’s loads more. An important distinction to make here is that, while biofuels all come from a renewable source (i.e. biomass), this doesn’t automatically make them all ‘green’, or environmentally friendly. ‘Green’ sources of energy are dubbed as such because they pose no threat to the environment.
Image source: LIU
Since some types of biofuels do produce greenhouse emission, this means that not all of them are green.
Biofuel Pros and Cons
The implied comparison, when discussing the pros and cons of biofuels, is that with fossil fuels. Around the world, biofuels and fossil fuels are used together or alternatively, depending on their availability and cost, but also on the availability of food in a given area. Let’s take a look at how these factors affect the two types of biofuels.
|Price||Expensive. The process of extracting fossil fuels from the ground has always been complicated, which, in turn, has maintained their costs at high levels.||Substantially cheaper. It has always been more economically affordable to produce biomass than to extract fossil fuels—unless you factor in the effects on food resources (see below).|
|It’s worth mentioning that technological advances have had a positive impact on the cost of biofuel production, but also on that of extracting fossil fuels. In what concerns price, the complexity of the production process is an essential influencing factor.|
|Availability||Not renewable. It’s common knowledge that, at some point, Earth’s fossil fuels resources will be depleted. With ever lower availability, prices will continue to climb.||Renewable, but not limitless. When biofuels first emerged, it was believed that they would never run out. As it turns out, humanity has yet to find a method to produce biomass at a pace that can keep up with our growing energy needs.|
|Food availability||Not directly linked. Fossil fuel extraction and the consumption of non-green fuels does affect the environment, though. The increased incidence of acid rain, larger greenhouse emission rates||Strongly linked. In most cases, growing biomass for biofuels takes up some of the limited available land for food farming. Right now, the Earth doesn’t have enough land available both for food and for biomass. This affects both the price of food and the price of biofuels, while rendering the latter unaffordable in poorer countries.|
Biofuels do take a toll on the world’s tally of available farmland. At the same time, though, it’s important to note that not all biofuels come with this disadvantage: growing algae, for instance, might one day only take up ocean space.
Image source: Biopact
If you’re curious about the actual facts and figures, here’s some data which shows the amount of land needed to cover just the world’s needs for jet fuel (i.e. 13% of total consumption):
- for Jatropha: 2.7 million sq. km = 1/3 of Australia;
- for Camelina: 2 million sq. km;
- for algae: 68,000 sq. km = Ireland.
Algae do stand out, in the landscape painted by the numbers above. While covering all of the world’s fuel demands with Jatropha would require 27 million sq. km (= Russia, the U.S., and a little more), algae need only 680,000 sq. km, which is roughly the size of France. While algae can be easily genetically manipulated, they still require a lot of water, which makes their current net energy yield unsustainable.
The cost of biofuels
From the above, it’s easy to notice that the cost of biofuels, tied in with their effect on food resources, represent an important argument against these renewable energy sources.
This is why biofuel R&D is currently receiving less government funding than it did in the early 2000s. In 2011, the U.S. Senate voted to stop tax breaks and commercial protection for the production of ethanol based on corn. Note that the U.S. is the second largest producer of ethanol in the world.
Meanwhile, at a global level, biofuels are still regarded as an economically viable alternative—not right now, yet at some point in the future. Here are the main issues pertaining to the socio-economic costs of biofuels:
- Moderating the price of oil. Merrill Lynch commodity experts have outlined that biofuels mitigate crude oil and gasoline trading prices by 15% and 25% respectively. This view is shared by the Canadian Renewable Fuels Association, which maintains that biofuels help keep oil prices from exploding.
- The “food vs. fuel” (“food or fuel”) debate. This debate is actually very controversial at global levels. The short versus long term effects of using farmland for biomass crops (as opposed to food crops) are difficult to ascertain, given the many factors that impinge upon pricing. These factors include governmental market involvement, government subsidies, and the use of several, divergent economic models in the academic side of the debate. Those who argue that biofuels are sustainable from this point of view explain that ethanol is produced from what would be an inedible part of the corn (the starch).
Image source: Mercopress
- Effects on poverty in developing countries. This, too, is an unsettled debate, as of yet. On the one hand, some argue that, since many developing countries import oil, biofuels would help stabilize prices and create employment. On the other hand, this would not apply to countries with limited resources for agriculture. One proposed solution to this debate is a country-by-country assessment of the economic viability of biofuels.
Biofuels and pollution
If biofuels produce greenhouse emissions, doesn’t this make them as harmful for the environment as fossil fuels? Could the impact of biofuels on global warming come to be reduced in time?
- Carbon dioxide
In what concerns carbon dioxide, the answer to this could be yes—at least in an ideal scenario.
The reality is that biofuels do produce carbon dioxide, one of the most powerful greenhouse gases. But it’s also true that the plants that biomass is made of consume some of that carbon dioxide. In other words, if biofuel CO2 consumption and production can be balanced to the point of zero net increase, their contribution to climate change would become irrelevant.
Unfortunately, reality falls short of the ideal. In fact, research undertaken at Cornell University in 2005 found that the technology involved in producing ethanol from corn consumes 30% more energy than it produces.
All in all, burning biofuels is cleaner than burning fossil fuels. However, when the entire production cycle is also factored in, the situation looks somewhat different. Here are the facts, in terms of grams of CO2/MJ of energy each type of fuel produces:
- Coal: 112g;
- Sugar cane biofuel: 107-18g;
- Corn biofuel: 103-49g;
- Wheat biofuel: 98-58g;
- Diesel: 86g;
- Gasoline: 85g;
- Natural gas: 62g.
“So, what’s up with those huge variable ranges for all the biofuels?” you might wonder. The answer lies in the origin of each feedstock crop. As is only logical, it’s far more sustainable to produce sugar cane biofuel in Brazil than it is in South Africa.
- Nitrous oxide
As you may already know, CO2 is not the only greenhouse gas around. Other substances, such as nitrous oxide, fall into the same category. Nitrous oxide also happens to be the main by-product of the majority of fertilizers. Fertilizing substances help plants turn molecular nitrogen into elemental nitrogen, via bacteria.
Contrary to the result of previous research, bacteria also produces a lot of N2O. So, while using biofuels could even out the output of CO2, the problem of N2O would still remain.
Whenever alcohols such as ethanol are oxidized, they release certain aldehydes into the atmosphere. Many of these substances are toxic to living organisms and have been linked to respiratory problems, chronic migraines, and lung diseases.
While the link between aldehyde production and biofuels is still being researched, here are some preliminary facts:
- The European Union has completely banned formaldehyde and classes it as a carcinogenic substance. Acetaldehyde is classed as carcinogenic and mutagenic by the World Health Organization and the U.S. Environmental Protection Agency.
- Gasoline mixed with ethanol (the U.S. standard) produces 40% more aldehyde emissions than pure gasoline.
- In Brazil, cars running on ethanol are a common occurrence. Tests have shown that the air in Sao Paulo, Brazil, contains 160% more formaldehyde and 260% more acetaldehyde than the air in cities where ethanol fuels are not burned.
The impact of biofuels on the environment
It’s very important to understand that more scientifically sound research is needed on the environmental impact of each distinct biofuel on the environment. They were definitely not created equal, neither in terms of greenhouse gas emissions, nor in what concerns their impact on food, land, soil, water, and biodiversity.
That being said, here are some proven issues that some biomass crops have caused the environment:
- Soil erosion
With an increase in demand for biofuels, several areas around the globe have also seen massive deforestation of mature trees. In Indonesia, for instance, palm tree plantations have replaced nearly 10,000,000 acres (38,000sq km) of forest.
This large-scale phenomenon has caused the erosion of soils, as well as reduced photosynthesis capacities. Mature trees absorb more CO2 than most crops used as feedstock for biofuel.
- Water consumption
There are two main ways in which biofuel production affects global water resources:
- For irrigating biofuel feedstock crops;
- For boiling/cooling production mechanisms in refineries.
In the U.S., for instance, the Energy Independence and Security Act states that biofuel production needs to increase substantially by 2022. Increasing yields for sweet sorghum, pine, sugarcane, and corn would take a heavy toll on the freshwater resources of Georgia and Florida. Sweet sorghum alone would up water needs by as much as 25%.
All in all, it has been estimated that producing biofuels consumes 2 to 84 times more water than fossil fuel production. And, yet again, it’s worth mentioning that some feedstocks don’t need to be irrigated, so a focus on those crops could be the solution in areas where water is scarce.
On the one hand, there are plenty of arguments in favor of growing a single type of crop on a given plot of farmland: it’s more efficient for the energy yield, since you can select the best performing crop; fewer resources (water included) are required for mono-crops.
On the downside, though, mono-crops lead to an increase in the population of pests that target that particular crop. Pesticides will also only work to a certain extent and, in time, the pests will become resistant to them. So, at the end of the day, producing biofuels also comes with the major risk of growing ‘super pests’ in tow.
Where is biofuel produced?
In what concerns the production of biofuels, the situation isn’t that much different from that of fossil fuels. In other words, certain crops are more popular in certain areas. Let’s take a look at the situation on a global level.
As previously mentioned, you’ll notice that, while bioethanol is more popular in the two Americas, Europe and the rest of the world seem more partial to biodiesel.
|Area||Country||Output in liters||Main feedstock||Type of fuel|
|North America||40 billion||Corn
|United States||40 billion||Corn
|South America||25 billion||Corn
|4 billion||Castor beans
|Brazil||25 billion||Sugar cane||Bioethanol|
|Australia & Asia||4 billion||Palm oil||Total biofuel|
Recycled cooking oil
|India||1 billion||Sugar cane
|Australia||500 million||Sugar cane|
|Africa & the Middle East||2 billion||Dung