A biofuel is a fuel that is produced through biological processes (such as agriculture) as opposed to geological processes (like fossil fuels). Renewable biofuels either involve carbon fixation, such as those that occur in plants or microalgae through the process of photosynthesis; or, they are created by the conversion of plant material. Conversion of plant material is by one of three mechanisms: thermal conversion, chemical conversion, or biochemical conversion.
Examples of biofuels include bioethanol, which is an alcohol made by fermentation of carbohydrates produced in sugar from a crop like corn. The bioethanol can be used as a fuel for vehicles or as a gasoline additive. A similar example is with biodiesel. A third use with the generation of methanol, which is a liquid and easy to transport. Biodiesel is made from rapeseed oil and other plant oils. It can be used in diesel-powered vehicles without needing any modifications to the engine. The fourth major biofuel is biobutanol, which has slightly less energy than gasoline, but can run in any car that uses gasoline without the need for modification to engine components.
Why are biofuels needed?
One reason for considering biofuels to address future energy needs is due to the depletion of fossil fuels as a result of the activities of the petrochemical industry. A second reason is the environmental impact that the continued use of fossil fuels is having on the planet, especially in relation to the emission of greenhouse gases (like carbon dioxide), leading to global warming. A third factor is sustainability, given that the raw material for many biofuels is self-renewing (such as plant biomass). A fourth factor is efficiency and the better integration of biofuels with new technologies.
Why are there concerns with the use of biofuels?
The main challenge to the use of biofuels is with the amount of arable land needed to grow plants to provide the necessary biomass. Biomass is simply organic matter. In others words, it is dead material that was once living.
Many campaign groups are concerned that land that should be used for growing food crops is being turned over to grow plants used in biofuel production. This is on the basis that plant matter should for biofuel production is more lucrative and at the detriment of providing sufficient food, especially in developing regions of the world.
There is a solution, however, and this is algae, especially types of microalgae called diatoms. Diatoms are microscopic algae that are major contributors to marine ecosystems; they are also the basis of diatomaceous earth, which is used by gardeners as a natural pest deterrent.
Microalgae
One renewable source of the biomass needed for biofuels can come from microalgae. Algae create hydrogen with the assistance of the enzyme hydrogenase, which breaks down when oxygen is present. This is more sustainable, and arguably more acceptable for society, than sacrificing crops that would otherwise be grown for food. The use of the ocean-based biomass allow for the production of oil without using up arable land and drinking water.
A further advantage with microalgae is that they can grow with light, water, carbon dioxide and a small amount of minerals, which means little in the way of inputs are needed and that the biomass can be harvested all year round. Moreover, the algal cells divide quickly which results in the biomass harvested more quickly than land-based biomasses.
Boosting biofuel efficiency
In relation to making biofuels more efficient some interesting new research has been reported. This is based on understanding the mechanism behind oil synthesis within microalgae cells and this new understanding could contribute to the discovery of biofuels. One question with the use of microalgae is which species are the most appropriate to use?
To find this out a research project has captured the metabolic changes occurring on a molecular level when lipids are produced in algae cells. Studying this in detail has allowed researchers to assess which types of algae are the best candidates for providing the necessary biomass for biofuel production. The research has been undertaken by a team headed up by Professor Hasunuma Tomohisa together with Kato Yuichi, who are employed at Kobe University Graduate School of Science, Technology and Innovation.
Looking at marine microalgae the research has concluded that a species called Chlamydomonas sp. JSC4 is a strong candidate. This is a species of green alga harvested from brackish water. The reason why this species comes out top is because it has a high growth rate and it can produce high levels of lipids. To show this the scientists used a technique called “dynamic metabolic profiling”. This method was used to analyze JSC4 and assess how the organism produces oil within its cells.
To study this, the researchers incubated JSC4 with carbon dioxide. It was found that within four days of incubation more than 55 percent of cell weight consisted of carbohydrates. However, when saltwater was added to the incubation liquid (about 2 percent), there was a decrease in carbohydrates and increase in oil. At seven days, with the saltwater mix, over 45 percent of the cell weight had become oil. This is regarded as very efficient. This happens because the sugar biosynthesis pathway in the organism slows down and instead the pathway for activating triacylglycerol it switched on. Triacylglycerol is a constituent element of oil so it is expected that using this metabolic mechanism will increase the production of biofuels.
The new study has been reported to the journal Scientific Reports. The research paper is headed “Dynamic metabolic profiling together with transcription analysis reveals salinity-induced starch-to-lipid biosynthesis in alga Chlamydomonas sp. JSC4.”
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we considered neuroscience and considered how scientists are using the light and sound methods to study the brain. The previous week examined whether B12 vitamins can help boost brain function. This centered on studies where seniors eat either peanut butter or Marmite each day.
