Renewable energy resources can be used over and over again. Renewable resources contain wind, geothermal energy, solar energy, hydropower and biomass. That resource generates much less pollution, both in gathering and production, than nonrenewable sources. The sun produces the solar energy. Some people use solar panels on their homes to convert sunlight into electricity. Dams and rivers generate hydropower.
When water flows through a dam it activates a turbine, which runs an electric generator. Biomass includes natural products such as wood, manure, corn and algal biomass of living organisms which used as energy source. Biomass, a renewable energy source, is organic matter resulting from living, or newly living organisms. It can be used as a source of energy and it most ultimately pointed to plant-based materials which are not used for feed, and are specially named lignocellulosic biomass.
Biomass can either be used in a straight line throughout burning to create heat such as forest residues and municipal solid waste, or indirectly after converting it to various types of biofuel. Conversion of biomass to biofuel can be summarized by different methods which are generally classified into: thermal, chemical and biochemical methods [ 11 ].
Biomass is considered the simply source of fuel for domestic use in several developing countries even today. Biomass is entire biologically created matter based in hydrogen, carbon and oxygen. The assessed biomass yield in the world is Even today, wood remains the largest biomass energy source [ 22 ]; examples include forest residues such as dead trees. Wood energy is derived by using lignocellulosic biomass second-generation biofuels as fuel.
Depending on the biomass source, biofuels are divided generally into two main groups. First-generation biofuels are resulting from origin such as corn starch and sugarcane. Sugars existing in the biomass are fermented to yield bioethanol, which can be used immediately in a fuel to yield electricity or act as a flavor to gasoline [ 23 ]. Second-generation biofuels use non-food-based biomass sources, for instance, municipal waste and agriculture.
These biofuels are often composed of lignocellulosic biomass, which is not edible and is a low-charge waste for several industries.
Although being the favored substitute, except the second-generation biofuel neither yields an inexpensive production nor achieved by technological issues. These issues appear essentially due to chemical slowness and building inflexibility of lignocellulosic biomass [ 24 ]. Energy derived from biomass is projected to be the largest non-hydroelectric renewable resource of electricity in the US between and by Energy Information Administration [ 25 ].
There is research involving algae as non-food source can be yielded at rates of times those of other kinds of land-based agriculture, for example, soy and corn. As soon as gathered, it can be fermented to yield biofuels, for example, ethanol and methane, in addition to hydrogen and biodiesel [ 26 ].
Resources of biomass include primary, secondary and tertiary. The first one primary biomass resources consisted directly by photosynthesis process and are income directly from the land. They contain permanent short-rotation woody crops and herbaceous crops, the seeds of oil crops and remains produced from the collecting of forest trees and agricultural crops.
Secondary biomass resources result from the processing of primary biomass resources such as agricultural by-product field crop residues and water vegetation algae, seaweeds, etc. Tertiary biomass resources are post-consumer residue streams including animal fats and greases, used vegetable oils, packaging wastes and construction and demolition debris [ 27 ] as shown in Table 2. Algae used as third generation of biofuels production. This generation of biofuels is advanced and is based on biological.
Microalgae are prokaryotic or eukaryotic photosynthetic organisms. Indeed, they can grow quickly in fresh or salt water due to their unicellular or simple multi-cellular building structure. Because of their simple cellular structure, they are very capable converters of solar energy. As the cells of microalgae grow in aqueous suspension, they have efficient access of water, CO 2 and other nutrients [ 29 ].
Microalgae are one of the oldest living organisms in our planet and have more than , species. Table 3 shows oil contents of different microalgal species [ 30 ]. Microalgae can grow in wastewater, thus giving it the ability to address treatment, utilization and disposal concerns [ 9 ].
Also, it can be grown in arid and semi-arid regions with poor soil quality, with a per hectare yield estimated to be many times greater than that of even tropical oil seeds [ 9 ]. Microalgae can be considered as a sustainable energy source of next generation biofuels [ 31 ]. Microalgae are able to create oil along the year.
Microalgae produce oil is more compared to conventional crops. Microalgae yield 15— times greater oil for biodiesel production than traditional crops. Biodiesel yield from algal lipid is distinguished with a high biodegradable and non-toxic.
Microalgae can cultivate in high amounts arrived to 50 times greater than that of switchgrass, which is the more growing terrestrial crop. Microalgae can complete the whole growth cycle in limited days by way of photosynthesis process that alters sun energy into chemical energy. They grow in fresh water, seawater, wastewater or non-arable lands [ 5 ].
The cultivation of microalgae needs less water than other energy oil crops. Table 4 shows the comparison between the different sources of biodiesel [ 32 ]. Production of biodiesel from microalgae can fix CO 2. Roughly 1 kg of algae biodiesel fixes 1. Microalgae cultivation has a higher CO 2 mitigation rate between Microalgae cultivation can use phosphorus and nitrogen as nutrients from wastewater resources.
Therefore, microalgae can provide the additional advantage for wastewater bioremediation. Furthermore, microalgal biodiesel can decrease the liberation of NO x. Microalgae yield significant by-products for instance H 2 , ethanol, biopolymers, carbohydrates, proteins, beautifying products, animal feed, enricher, biomass remains, etc.
Improvement of microalgae does not need stimulant for growth. The warming value of microalgal biodiesel is greater than that of the other terrestrial plants. Algal biomass is a renewable resource that has the potential to supply a limited portion of international energy needs [ 36 ]. Preference toward microalgae is due largely to its less complex structure, fast growth rate and high-oil content for some species This characteristics of the strain should be taken into consideration. There are greater than , types of algae, with varying ratios of three main types of molecule: protein, oils and carbohydrates.
Types of algae great in carbohydrates in addition to oils create starches that can be liberated then fermented into ethanol; the residual proteins can be converted into animal grains [ 1 ].
Research into algae for the mass-production of oil is mainly focused on microalgae organisms capable of photosynthesis that are less than 0. In the end of eighteenth century, Robert Koch was one of the first scientists focused on the isolation of microorganisms in pure culture, followed by Sergei Winogradsky who initiate the field of microbiology and he was responsible for the first isolation of microorganism.
There are four main techniques for obtaining unialgal isolates: spraying, streaking, serial dilution and single-cell isolations [ 37 ]. Spraying and streaking are useful for single-celled, colonial or filamentous algae that will grow on an agar surface; cultures of some flagellates may also be founded by these methods.
A lot of flagellates and in addition to other forms of algae, must be separated by single-organism isolations or serial-dilution procedures. Spraying procedure, a stream of air is utilized to diffuse algal cells from a mixture onto the surface of a petri plate having solidified medium with agar for growth.
Hold a pipette in both hands; the tip end is caught with a forceps so that the glass near the tip is within the flame of a Bunsen burner gas flame. The pipette is held in the flame only until the glass becomes marginally soft. This is determined by testing for flexibility by moving the tip with the forceps. Then the pipette is removed from the flame and pulled out straight or at an angle so that there is a bend.
You can differ the diameter of the fine pulled tip by altering the speed of pulling. You would need a fine diameter tip if you are trying to separate very small algae, but a bigger diameter tip is necessary for large cells. Addition of antibiotics to the growth medium is necessary to prevent growth of cyanobacteria and other bacteria, while addition of germanium dioxide will inhibit diatoms growth. Treatment of culture, isolated algae, by an extensive washing procedure via one or more antibiotics is called axenic culture.
Resistant stages such as zygotes or akinetes can be treated with bleach to kill epiphytes, and then planted on agar for germination. Two basic alternatives for microalgae cultivation exist and their relative merits are the basis of ongoing debate. Microalgae cultivation using sunlight energy can be carried out in open ponds, covered ponds or closed photobioreactors, based on tubular, flat plate or other designs [ 38 ].
Algae houses are utilizing numerous variance methods to grow the algae, involving covered ponds, open ponds, bioreactors and raceways. Algae grow normally in brackish, fresh or salt water centered on the algae species. An algal biofuels house must assess the cost and accessibility of water at the site of the production capacity. Water evaporation is the main problem, may be depending on the climate or whether of the system that used for growth of the algae open or closed. Table 5 presents a short comparison of open pond systems and closed photobioreactors.
Each system has benefits and drawbacks with respect to optimal growth conditions. Advantages and disadvantages of open pond and closed systems which are used for algal growth. Figure 6 shows fixation of carbone dioxide in photobioreactors, utilizing microalgae to convert carbon dioxide and solar energy into algal biomass through photosynthesis process. The microalgae transferred to isolated photobioreactor for hydrogen creation, where the algae will transform solar energy into hydrogen gas using a biophotolytic procedure under sulfur deficiency.
After the hydrogen yields stage, the algal biomass will be gathered and used for various purposes: the algae can be utilized immediately as a food for human or as animal feed or in aquaculture. After nutrient control, algal biomass can hold big quantities of important biomolecules, which will be removed for industrial trade.
However, these substances generally contain few percent of the biomass, leaving the common of the fixed carbone dioxide in the residual biomass. The remaining algal biomass from different method steps can be utilized either as a fertilizer for agriculture in which case the fixed carbon will be retained for some years, or for storing of the fixed carbone dioxide by industrial uses like manufacture of plastics.
Remaining biomass can also be utilized as an energy transporter by removal of biodiesel through the direct conversion of the biomass to other energy transporters by biological or thermochemical procedures [ 39 ]. Fixation of carbone dioxide in photobioreactors, utilizing microalgae to convert carbon dioxide and solar energy into algal biomass through photosynthesis process. Photobioreactors, the closed systems are much more expensive than ponds.
PBR can have different sizes and shapes: plastic bags, flat panels, tubes, fermenter like and others, as shown in Figure 7. Vertical tubes are the most popular system due to their relatively easy maintenance, high surface to volume ratio and low cost [ 40 ].
Between the advantages of utilizing photobioreactors are resistance to infection with uninhabited algae types and the possibility of simply controlling different factors, including temperature, light intensity and pH. The PBR can be located outdoors or indoors using artificial light or sunlight or a mixture of both. A recent study showed that different wavelengths may have a significant influence on biomass and lipid productivity, as well as on the lipid profile [ 41 ].
Different shapes of closed system. Open ponds can be considered a cheap and easy to build, as extended as the area is relatively flat. Cultivation can be prepared immediately above the soil and some simple surface covering for reducing water loss due to seepage, and the other enhancements can be prepared to increase solar energy capture, and reduce the contamination process.
The most common types are raceway Figure 8 , circular, inclined and unmixed. Open-pond systems for the most part have been given up for the cultivation of algae with high-oil content [ 43 ]. Open systems using a monoculture are vulnerable to viral infection. However, such open ponds also suffer from various limitations, including more rapid than closed systems biological invasions by other algae, algae grazers, fungi, amoeba, etc.
It became a main problem, limiting its latter problem is offered. Wastewaters and marine waters can be used as environment and considered a good match for this system due to the water sustainability issues that would prevent large open-pond cultivation from using potable water and the cost of this operation is relatively low.
Therefore, this system is able to generate the biomass with a good price [ 44 ]. In general, open ponds constitute the cheapest method of producing algae in large quantities [ 45 ]. Open system raceway pond. Nutrients such as phosphorus P , potassium K and nitrogen N are vital for microalgae growth and are necessary quantities of fertilizer. Iron and silica, in addition to many trace elements, which considered essential marine nutrients, the lack of one can limit the growth of microorganism.
A suitable nutrient source for algae is from the sewage wastewater treatment, agricultural, flood plain run-off, all presently major pollutants. However, this wastewater cannot feed algae immediately, but the first process through anaerobic digestion by bacteria. If wastewater is not processed before it reaches the algae, it will possibly kill much of the desired algae strain.
The early research suggests algae could produce more biofuel per hectare than current methods using commercial crop residue. In Australia, the CSIRO is looking into the best algal strains for producing biofuels, and assessing our algae resources.
While commercialisation is still a way off, the CSIRO is working to improve the feasibility and efficiency of algae production, harvesting and processing. Barramundi fillets are made even better with this easy pistachio and herb pesto. Perfect for…. Fossil Fuels. Nuclear Fuels. Acid Rain. Climate Change.
Climate Feedback. Ocean Acidification.
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