- Biofuels are produced from various types of plant material. It is high-carbon, high-energy plant material whose energy yield is derived from captured CO2. The process requires sunlight for rapid conversion.
- Biofuels are all about energy yield. All living organisms require more energy than they consume to grow, mature and maintain their life functions. The process of energy conversion is different for all plant species. Certain biofuels have a higher energy conversion rate.
- There are several examples of energy crops with higher energy yield. One such example would be algae biofuel. Various attempts have been made to commercialize algae biofuel. Some of these attempts were successful, others came to nothing.
- Biofuels can only be obtained from plants that grow quickly. Different amounts of CO2-enriched atmosphere and different levels of solar radiation are required to maintain the energy demand of plants and the growth cycles of each plant species.
- Biofuels are derived from plant material that breaks down into its various chemical components.
1. ARE ALL BIOFUELS MADE FROM PLANTS?
Are fossil fuels just another form of biofuels? According to the peak oil theory, conventionally recoverable oil is deposited on the ocean floor. Over millions of years, dead marine organisms have accumulated on the ocean floor.
Oil consists of these organics. They gradually decomposed into liquid form. This transformation from organic matter into oil required pressure and heat. The concentration of decomposed organic matter with a high calin an oxygen-deficient environment allowed oil to form.
Where did this transformation take place? In shallow, warm oceans. The organic material was exposed to pressure and heat. Over time, organic material gradually accumulated on the ocean floor in these shallow waters. In some regions, such as the Persian Gulf, the geologic plates moved little. This contributed to the accumulation of dead organic material on the seafloor. This allowed even more organic material to be deposited in one place. The organic material decomposed. The oil became trapped between hard rock layers and continued to decompose.
The key feature of biofuels, then, is that they fall into the realm of organic chemistry rather than inorganic chemistry when it comes to their origins. The definition of synthetic fuel is somewhat different. Synthetic fuel can be made from recycled plastic waste and R-PET. These are just a few examples. In a sense, the process of making synthetic fuel simulates the natural geological process. Pyrolysis may involve heating shredded, relatively homogeneous plastic waste in an oxygen-deficient environment. If all goes well, a relatively pure pyrolysis oil is obtained. Other fuel components can be used in the chemical industry.
Another example is biodiesel from local sources, which is commonly blended with conventional diesel fuel. The biodiesel is an admixture to make combustion more efficient.
2. ARE ALL BIOFUELS RENEWABLE?
Most biofuels are renewable because they are a concentrated, high-carbon form of energy. Biomass and plants take a long time to store energy, mostly from the sun. The sun is our most important source of energy on this planet. This has not changed since the dawn of mankind, and for most of our history we have used plants to meet our energy needs. However, plants are not as efficient at storing energy. Plants cannot extract so much energy from the sun’s rays that we could use it, without other energy sources. It takes too long to store the energy we need to meet our needs. The energy conversion process is not as efficient as modern solar panels, which have been optimized to convert solar radiation into electricity. In this sense, renewability is a key feature of biofuels.
Biomass hardly provides us with more energy than the cultivation of energy crops has required. The good news, however, is that we can grow them continuously. In that sense, they are renewable. Hard coal, and to some extent lignite and hydrocarbons, are also based on plants. They have accumulated solar radiation and provide us with a surplus of energy. However, the question remains whether hydrocarbons are renewable, because we don’t have a million years to regrow them. So the most likely answer is that hydrocarbons and coal liquefaction are not biofuels.
It is not always possible to guarantee that biofuels are 100% renewable. Supply chains play a role. Biomass travels from A to B to collect biomass from different sources. Industrial processes are needed to treat biomass and convert biomass into biofuel. This is especially true for second generation biofuels.
3. DO BIOFUELS HAVE TO BE GREEN?
Not necessarily. The green color is due to chlorophyll. Let’s take an example. The starchy material that is pressed and crushed to make sugar cane is brownish in color with slight green undertones. The aging of the sugar cane plant plays a role. The sugar cane must be stored on site before it is fed into the treatment plant. The author of this website has seen the processing of the sugar cane. In Brazil, the brownish sugar cane plants are used to produce bioethanol. The resulting fuel has a light brownish color, but just like vegetable oil, it turns a yellowish hue after treatment.
The answer is that biofuel need not be green. In many cases has a yellowish tinge.
4. DOES SUSTAINABLE AVIATION FUEL COUNT AS BIOFUEL?
Sustainable aviation fuel would be considered biofuel if more than 50% of it is derived from biogenic, organic sources. Sustainable aviation fuel can be produced from a variety of feedstocks. Waste materials include municipal solid waste, recycled plastics, and organic waste. Depending on the fuel source, different pyrolysis oils can be obtained. The concentration of tar and other residues from the treatment process varies in each case.
We should always weigh the pros and cons of each type of fuel. Biofuels come in different shades and colors. Each energy source has its own advantages and disadvantages, and biofuels are no exception. We should evaluate the advantages and disadvantages of each biofuel source individually.
5. CONCLUSION: WHAT ARE BIOFUELS?
- Most biofuels derive from biomass.
- Depending on our definition, hydrocarbons can be considered biofuels in that they come from biogenic sources. These sources may consist in part of decayed marine microorganisms, algae, and plankton.
- Hydrocarbons cannot be considered renewable because, from a geological perspective, it takes time to renew the supply of hydrocarbons.
- Biofuels can be considered renewable energy sources. This does not mean that all biofuels are renewable in the true sense of the word. This is because energy crops have a growing season. In order to grow them, we need land to grow these energy crops. Sugarcane production takes up a lot of land in Brazil that could be used to grow food instead.
- Biofuels do not have to be green. Many biofuels have a yellowish color.
- Sustainable aviation fuel (SAF) and other types of renewable fuels can be considered biofuels if more than 50% of the fuel inputs come from biogenic sources.