Abstract
This study presents designing and managing a green fuel supply chain based on algae to investigate the development of such fuels in the country. On this basis, a definitive model is first developed to model all the activities of the green fuel supply chain, which includes the supply of raw materials for the growth of algae, the cultivation of algae and their conversion into fuel, and finally, the supply of fuel in the country. This deterministic model is extended to a robust network model to secure supply chain decisions against uncertainty. Using the proposed model for the development of algal fuels in Iran shows that the green fuel production cost is currently 27 cents/liter. The current cost of producing fuel from algae cannot compete with fossil fuels, but this cost can be greatly reduced in the future by slightly increasing the growth rate of algae and their oil content.
TopIntroduction
Environmental pollution from fossil fuel consumption, together with rapid consumption, limited oil reserves, and increasing energy demand are the most important motivations for developing new energy. Among new energy sources, biomass-based green fuels have gained considerable importance in recent years. This is because biomass fuels can replace fossil fuels without changing the transport fleet (Yue et al., 2014). In addition, the uptake of carbon dioxide during growth reduces the net amount of carbon dioxide entering the atmosphere and consequently reduces environmental hazards (Sims et al., 2010). To date, various raw materials have been used to produce green fuels. The most important raw materials are corn, sugarcane, soybeans, and oilseeds (Mata et al., 2010). Although the production of fuel from these materials has been done economically in many parts of the world, it has faced severe criticism in recent years because these fuels are extracted from the edible food and adversely affect the agricultural market (Davis et al., 2011). Such problems have led to attention being paid to the use of non-food primary sources for fuel production. The most important primary non-food sources known as the second generation of fossil fuels are corn husks, grass, spruce, jatropha, and bamboo (Sims, 2010). Although this generation has fewer adverse effects on food markets, they do not have high productivity and need adequate water and fertilizers for the agricultural sector, making them unable to produce green fuel on a large scale. Among the types of raw materials without a food source, microalgae (tiny-celled species of algae) have many biological and technical properties and characteristics that have made them one of the most desirable and promising raw materials for green fuel production in coming years. The most important advantages of microalgae are high growth rate as well as high oil storage capacity (Sims, 2010), the ability to grow in brackish water and wastewater, which can help in minimizing the need for fresh water. In addition, microalgae having the capability to use the greenhouse gases emitted from the power plants and converted into fuel in their cells (Maity et al., 2014).
Key Terms in this Chapter
Algaculture: Algaculture is a form of aquaculture involving the farming of species of algae. The majority of algae that are intentionally cultivated fall into the category of microalgae (also referred to as phytoplankton, microphytes, or planktonic algae). Macroalgae, commonly known as seaweed, also have many commercial and industrial uses. Still, due to their size and the specific requirements of the environment in which they need to grow, they do not lend themselves as readily to cultivation (this may change, however, with the advent of newer seaweed cultivators, which are algae scrubbers using upflowing air bubbles in small containers). Commercial and industrial algae cultivation has numerous uses, including food ingredients such as omega-3 fatty acids or natural food colorants and dyes, food, fertilizer, bioplastics, chemical feedstock (raw material), pharmaceuticals, etc. algal fuel. It can also be used as a means of pollution control. Global production of farmed aquatic plants, overwhelmingly dominated by seaweeds, grew in output volume from 13.5 million tonnes in 1995 to just over 30 million tonnes in 2016.
Biofuel: Biofuel is the fuel produced through contemporary processes from biomass, rather than by the very slow geological processes involved in forming fossil fuels, such as oil. Since biomass can be used as a fuel directly (e.g., wood logs), some people use biomass and biofuel interchangeably. However, the word biomass simply denotes the biological raw material the fuel is made of or some form of thermally/chemically altered solid end product, like torrefied pellets or briquettes.
Solar Fuel: A solar fuel is a synthetic chemical fuel produced from solar energy. Solar fuels can be produced through photochemical (i.e., activation of certain chemical reactions by photons), photobiological (i.e., artificial photosynthesis), thermochemical (i.e., through the use of solar heat supplied by concentrated solar thermal energy to drive a chemical reaction), and electrochemical reactions (i.e., using the electricity from solar panels to drive a chemical reaction). Light is used as an energy source, with solar energy being transduced to chemical energy, typically by reducing protons to hydrogen or carbon dioxide to organic compounds. Solar fuel can be produced and stored for later use when sunlight is not available, making it an alternative to fossil fuels and batteries. Examples of such fuels are hydrogen, ammonia, and hydrazine. Diverse photocatalysts are being developed to carry these reactions in a sustainable, environmentally friendly way.
Algae Fuel: Algae fuel, algal biofuel, or algal oil is an alternative to liquid fossil fuels that use algae to source energy-rich oils. Also, algae fuels are an alternative to commonly known biofuel sources, such as corn and sugarcane. When made from seaweed (macroalgae), it can be known as seaweed fuel or seaweed oil. Several companies and government agencies are funding efforts to reduce capital and operating costs and make algae fuel production commercially viable. Like fossil fuel, algae fuel releases CO 2 when burnt, but unlike fossil fuel, algae fuel and other biofuels only release CO 2 recently removed from the atmosphere via photosynthesis as the algae or plant grew. The energy crisis and the world food crisis have ignited interest in algaculture (farming algae) for making biodiesel and other biofuels using land unsuitable for agriculture. Among algal fuels’ attractive characteristics are that they can be grown with minimal impact on freshwater 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. The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (39,000 km 2 ), which is only 0.42% of the US map, or about half of the land area of Maine. This is less than 1¤7 the area of corn harvested in the United States in 2000.
Second-Generation Biofuels: Second-generation biofuels are fuels made from lignocellulosic or woody biomass or agricultural residues/waste. The feedstock used to make the fuels either grow on arable land but are byproducts of the main crop or grown on marginal land. Second-generation feedstocks include straw, bagasse, perennial grasses, jatropha, waste vegetable oil, municipal solid waste, and so forth.
Fourth-Generation Biofuels: This class of biofuels includes electrofuels and solar fuels. Electrofuels are made by storing electrical energy in the chemical bonds of liquids and gases. The primary targets are butanol, biodiesel, and hydrogen, but include other alcohols and carbon-containing gases such as methane and butane. Solar fuel is a synthetic chemical fuel produced from solar energy. Light is converted to chemical energy, typically by reducing protons to hydrogen or carbon dioxide to organic compounds.
Third-Generation Biofuels: Algae can be produced in ponds or tanks on land and out at sea. Algal fuels have high yields, can be grown with minimal impact on freshwater resources, can be produced using saline water and wastewater, have a high ignition point, and are biodegradable and relatively harmless to the environment if spilled. Production requires large amounts of energy and fertilizer, the produced fuel degrades faster than other biofuels, and it does not flow well in cold temperatures. By 2017, due to economic considerations, most efforts to produce fuel from algae have been abandoned or changed to other applications.
First-Generation Biofuels: First-generation biofuels are fuels made from food crops grown on arable land. The crop’s sugar, starch, or oil content is converted into biodiesel or ethanol, using transesterification or yeast fermentation.