Third Generation Biofuel: A Sustainable Source of Energy

Increasing energy demand is a serious issue besides food and shelter through overwhelmed world. The requirement of energy for the mankind is increasing day by day.

By GHULAM ABBAS

World has already been confronted with energy crises due to depletion of finite resources of fossil fuel. Fossil fuel is the backbone to run global economy. However, major source of energy is based on fossil fuels only. It is observed that use of fossil fuel has affected in two- way: Unsustainable use cause depletion of resources and accumulating greenhouse gases like CO2 causing global warming, ozone depletion, consequently responsible for climate change. On other hand, the scarcity of fossil fuels causes rising price of petroleum-based fuels which leads huge economic threshold. Therefore, all worries of energy crises laying our focus on renewable energy sources such as solar, wind, hydro, tidal and biomass. Besides all the renewable energies, one of the most important energy sources in near future is biomass. There is different biomass from various sources like agricultural, forestry, and aquatic have been taken into consideration as the feedstocks for the production of several biofuels such as biodiesel, bioethanol, biohydrogen bio-oil, and biogas. The biofuel is benefited in several ways over traditional fuels like; greater energy security, reduced environmental impact, foreign

 

exchange savings and socio-economic issues. However, the environmental impact raised from burning of fuels has a great impact on carbon cycle (carbon balance), which is related to the combustion of fossil fuels. Besides, exhaustion of different existing biomass without appropriate compensation resulted in huge biomass scarcity, emerging environmental problems such as deforestation and loss of biodiversity. Therefore, an initiative has been taken to develop different solid, liquid, and gaseous biofuels as the alternative energy resources.

The current research and technology based on the third-generation biofuels/algal biofuel or algal oil is an alternative to liquid fossil fuels or other biofuels which are derived from algal biomass. It has been considered as the best alternative bioresource that avoids the disadvantages of first and second-generation biofuels. Algal biomass has been investigated for the implementation of economic conversion processes producing different biofuels such as biodiesel, bioethanol, biogas, biohydrogen and other valuable co-products.

What are Algae and how are they used?

 

Billions of years ago the earth atmosphere was filled with CO2. Thus, there was no life on earth. Life on earth started with Cyanobacteria and Algae. These humble and mysterious photosynthetic organisms sucked the atmospheric CO2 and started releasing oxygen. As a result, level of CO2 was started decreasing to such an extent that life evolved on earth. Once again, these miniature organisms are poised to save humanity from the threat of global warming. Algae are, micro e.g. chlorella and diatom to macroscopic e.g. giant kelp, mainly photo-autotrophs organisms, inhabitant of every possible habitat. They’re capable of producing algal biomass by converting CO2 and H2O by engaging sunlight. Algal cells can be converted in various types of fuels depending on techniques and part of cell used in. Microalgae are very small in sizes usually measured in micrometres, which normally grow in waterbodies or ponds. Microalgae contain more lipids than macroalgae and have the faster growth in nature. There are about more than 50,000 microalgal species out of which only about 30,000 species have been taken for the research study. The short harvesting cycle of algae is the key advantage for their importance, which is better than other conventional crops having harvesting cycle of once or twice in a year.

There are several advantages of algal biomass for biofuels production: (a) ability to grow throughout the year, therefore, algal oil productivity is higher in comparison to the conventional oil seed crops; (b) higher tolerance to high carbon di oxide content; (c) the consumption rate of water is very less in algae cultivation; (d) no requirement of herbicides or

 

pesticides in algal cultivation; (e) the growth potential of algal species is very high in comparison to others; (f) different sources of waste water containing nutrients like nitrogen and phosphorus can be utilized for algal cultivation apart from providing any additional nutrient; and (g) the ability to grow under harsh conditions like saline, brackish water, coastal seawater, which does not affect any conventional agriculture.

Among algal fuels’ attractive characteristics are that they can be grown with minimal impact on fresh water resources, can be produced using saline and wastewater, have a high flash point and are biodegradable and relatively harmless to the environment if spilled. Algae cost more per unit mass than other second-generation biofuel crops due to high capital and operating costs, but are claimed to yield between 10 and 100 times more fuel per unit area.

Research onto algae for the mass-production of oil focuses mainly on microalgae (organisms capable of photosynthesis that are less than 0.4 mm in diameter, including the diatoms and cyanobacteria) as opposed to macroalgae, such as seaweed. The preference for microalgae has come about due to their less complex structure, fast growth rates, and high oil- content.

Now adays, various species of algae are undertaken in research for finding the precursor molecules for biofuel. Common most species yield the biofuel are: Spirulina platensis, Nannochloropsis sp., Scenedesmus sp., Chlorella marina, Chlorococcum sp., Spirogyra sp. etc. lgal species are cultivated in photobioreactors, open ponds, closed loop systems and turf scrubbers on commercial scale.

 

Lipids or oily part of the algal biomass can be extracted by standard protocols. Extracted biomass is further proceeded to produce by-products such as bioethanol, biobutanol, biogas, bio-gasoline, biodiesel, green diesel and jet diesel. Said products are also investigated for economic implementation.

Green diesel can be produced (also known as renewable diesel, hydrotreating vegetable oil or hydrogen-derived renewable diesel) through a hydrotreating  refinery  process that breaks molecules down into shorter hydrocarbon  chains  used  in  diesel  engines. Interestingly, it has the same chemical properties as petroleum-based diesel meaning that it does not require new engines, pipelines or infrastructure to distribute and use. It has yet to be produced at a cost that is competitive with petroleum.

There is a clear demand for sustainable biofuel production, but whether a particular biofuel will be used ultimately depends not on sustainability but cost efficiency. Therefore, research is focusing on cutting the cost of algal biofuel production to the point where it can compete with conventional petroleum. Several companies and government agencies are funding efforts to reduce capital and operating costs and make algae fuel production commercially viable.

This technology must overcome a number of hurdles before it can compete in the fuel market and be broadly deployed. These challenges include strain identification and improvement, both in terms of oil productivity and crop protection, nutrient and resource allocation and use, and the production of co-products to improve the economics of the entire system. Although there is much excitement about the potential of algae biofuels, much work is still required in the field.

In Pakistan, research has also been made in field of biodiesel. Mostly higher plants are practiced for this purpose. Recently reported that research is also carried out to extract the biofuel from Algae. Being rich with algal diversity, oil extraction from it can be an opportunity for Pakistan to balance its production vs demand graph of fossil fuels. Being easy and economical its use can lead to the development of strong Algal Bio-fuel Production Industry in Pakistan.

Unfortunately, we are so far to produce biofuel as sustainable source of energy at commercial scale. For this purpose, we need development analogous to research.

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