What is Biofuel?
What makes biofuel unique from other renewable energy sources is that the biomaterial sources of this form of energy can be directly converted into liquid fuels. This conversion process is achieved through carbon fixation, which involves converting inorganic carbon that is present within the biomass to hydrocarbon fuel1. Since biofuel is organic matter, any type of material that was once living, such as algae, sugar cane or kernels of corn, can be considered as biomass and ultimately transformed into a form of renewable energy.
There are several advantages associated with biofuel, especially when compared to the use of fossil fuels. For example, fossil fuels can only be obtained by extraction from the earth, which is an expensive and often difficult process to achieve. Furthermore, fossil fuels are not renewable sources of energy and will ultimately run out. On the other hand, the production of biofuels is significantly cheaper and more simple to achieve as compared to that required for fossil fuels. In addition, while biofuels do produce carbon dioxide (CO2), which is considered a greenhouse gas, it is estimated that the amount of CO2 produced by biofuels will balance the amount consumed by growing plants.
Challenges for Biofuel
Some of the major limiting factors associated replacing fossil fuels with biofuels involves the inherent characteristics of most biomass sources, of which include high moisture content, low energy density and nonhomogenous chemical properties. In addition, the use of biomass sources that exhibit higher concentrations of alkali and other alkaline earth metals (AAEMs) can increase the chance of serious ash-related complications to occur2. To this end, various researchers are currently looking to how alternative energy conversion processes, such as hydrothermal carbonization (HTC) can address these limitations while also advancing the reality of replacing fossil fuels with biofuels in the near future.
Current BioFuel Sources
Aside from the numerous sources that can potentially be converted to biofuel, it is also important to recognize that the chemical structure of biofuels also vary. These biofuels, as well as the fossil fuel that they closely relate to, include:
- Ethanol → Gasoline/ethane
- Biodiesel → Diesel
- Methanol → Methane
- Biobutanol → Gasoline/Butane1
The conversion process and biomass source for the biofuel has a direct pact on exactly which type of biofuel will be produced. For example, bioethanol is typically obtained from feedstock sources, of which can include wheat, sugar beet, corn, straw and wood3, whereas biodiesel is typically obtained from vegetable oils. Bio-oils, which is a term used to describe liquid fuels, are typically obtained from the conversion of agricultural crops, municipal wastes, as well as various byproducts produced by both the agricultural and forest industries. Another type of biofuel known as activated biochar is obtained from agricultural residues that include fruit stones, nutshells and corn cobs2.
Bamboo for BioFuel
Bamboo naturally grows in large quantities throughout Africa, India and China, as well as various other nations around the world. As a result of the devastating deforestation and soil degradation that has occurred in a large majority of Ghana’s forests, researchers of this nation have turned to bamboo to solve this country’s growing fuel demands3. What is particularly useful about bamboo is that the entire plant, of which includes the stem, branch and its rhizome, can be used to produce biofuel in the form of charcoal and briquette. Recently, the International Network for Bamboo and Rattan (INBAR) has adapted bamboo charcoal technology in Ghana in an effort to increase production of bamboo charcoal briquettes that can be used for rural communities and replace the use of natural or traditional wood charcoal, both of which significantly contribute to air pollution in these areas.
As previously mentioned, the conversion process from biomass to biofuel plays a crucial role in determining the type of biofuel that will form, as well as what type of biomass source is appropriate for this method. HTC is regarded as a relatively simple process that converts raw biomass into solid biofuels. Some biomass sources previously converted by HTC include poultry litter, grape pomace, watermelon peel, sewage sludge and tobacco stock4. In a recent study, both HTC and a different biomass conversion process known as coupling washing with torrefaction (CWT) were used to convert bamboo sawdust into biofuel. In this study, the researchers found that both HTC and CWT were capable of safely converting bamboo sawdust to biofuel while simultaneously reducing potential ash-related issues from occurring4.
- “Biofuels: What are they?” – Biofuel.org.uk
- Zhang, S., Su, Y., Xu, D., Zhu, S., Zhang, H., & Liu, X. (2018). Assessment of hydrothermal carbonization and coupling washing with torrefaction of bamboo sawdust for biofuels production. Bioresource Technology 258; 111-118. DOI: 10.1016/j.biortech.2018.02.127.
- “Bamboo biofuel technology emnhancing Ghana’s green energy sector” – Climate Action
- Demirbas, A. (2008). Biofuels sources, biofuel policy, biofuel economy and global biofuel projections. Energy Conversion and Management 49; 2106-2116. DOI: 10.1016/j.enconman.2008.02.020.