In order to produce biodiesel from microalgae lipids, the later must be priory extracted. The main lipid extraction techniques are the use of chemical solvents, supercritical CO2, physicochemical, biochemical and direct transesterification. Chemical solvents extraction Chemical solvents method is by far the most commonly used, but less effective when microalgae are still wet (Samorì et … Read More

The large scale production of microalgae is generally performed with solar energy (photoautotrophic metabolism) in open ponds (raceways), closed systems (photobioreactors) or fermentors. Open ponds are generally circular with nested loops and are 30 cm deep (Chisti, 2007). However, ponds can have several non neglectable disadvantages. Indeed, as they are open, evaporation and contaminants (protozoa, … Read More

The effectiveness with which greenhouse gas emissions (GHGs, including CO2, CH4, and others) can be avoided using biofuels is related to the amount and carbon intensity of the fossil fuel inputs needed to produce the biofuel, as well as to what fossil fuel is substituted by use of the biofuel. A proper GHG accounting considers … Read More

Thermochemical biomass conversion involves processes at much higher temperatures and generally higher pressures than those found in biochemical conversion systems. Key intrinsic characteristics distinguishing thermochemical from biochemical biofuels are the flexibility in feedstocks that can be accommodated with thermochemical processing and the diversity of finished fuels that can be produced. Thermochemical production of biofuels begins … Read More

The fuel properties of second-generation ethanol or butanol are identical to those of the firstgeneration equivalents, but because the starting feedstock is lignocelluose, fundamentally different processing steps are involved in producing them. Second-generation biochemically-produced alcohol fuels are often referred to as “cellulosic ethanol” and “cellulosic biobutanol”. The basic steps for producing these include pre-treatment, saccharification, … Read More

A variety of pyrolysis processes have been developed to convert municipal solid wastes and agricultural and wood residues to solid, liquid and gaseous fuels. The thermal process can be designed to maximize the desired end products since the quantity of char, bitumen-like liquid and gas produced varies as a function of the time and temperature … Read More

The development of photosynthetic microbes that produce lipids or hydrocarbons also has great potential for biofuels production. While plant production of useable biomass is unlikely to exceed an overall solar conversion efficiency of 1-2 percent, algae can convert solar power at efficiencies in excess of 10 percent. A combination of anaerobic and aerobic microbial processes … Read More

First generation biofuels technologies comprise mainly of fuel ethanol from crops such as corn and sugarcane and biodiesel from crops such as rapeseed and soy. Second generation processes are those that produce energyefficient biofuels that do not compete with the food chain for feedstocks. Secondgeneration processes convert lignocellulosic materials, including agricultural and forest residues such … Read More

The first generation biofuels are those that are characterized by mature commercial markets and well understood technologies3. Some examples are sugarcane ethanol in Brazil, corn ethanol in the United States, oilseed rape biodiesel in Germany, and palm oil biodiesel in Malaysia. The development and use of first generation biofuels are encouraged by the desire to … Read More

The combustion of fossil fuels such as coal, oil and natural gas has been identified as a major cause of the increase in the concentration of carbon dioxide in the earth’s atmosphere. Carbon dioxide and other so-called greenhouse gases (e.g., methane) allow solar energy to enter the earth’s atmosphere but reduce the amount of energy … Read More