Energy demands have been increasing in recent years with the growing global population. Bioenergy is considered a vital component of addressing these growing demands and minimizing greenhouse gas (GHG) emissions. Recent research on bioenergy has shown that algal biofuels have potential as a feedstock to counter the effects of food in comparison to fuel crisis and deforestation. The carbon dioxide emitted during the combustion of fossil fuels can be recycled back to algal cultivation facilities, leading to a net reduction in overall GHG. Microalgae can also be grown in multiple water resources and have been shown to capture carbon from the atmosphere effectively sequestering nearly 1.8 kilograms of carbon dioxide per 1 kilogram of algae grown.
Hydrothermal liquefaction (HTL) has gained prominence in recent years as a method for thermochemical generation of usable energy products from algae. HTL uses an elevated temperature and pressure to convert wet biomass into energy-intensive liquid fuel feedstock (biocrude), a nutrient-rich water phase, and solid biochar under subcritical water conditions. There has been limited research on the use of HTL biochar in the cultivation of microalgae, especially thermo-acidophilic (low pH and high temperature) strains like G. sulphuraria.
Researchers at Arizona State University have developed a novel method for successful recovery of phosphorous and nitrogen from biochar, a by-product of the hydrothermal liquefaction process (HTL), and the ability to use the recovered nutrients for cultivating G. sulphuraria 5587.1 without inhibition. This method optimizes the recovery of nutrients from this process, and their utilization improves the economics of the process and has the potential to improve the value of algal biofuels. In addition to phosphorus in the biochar, initial tests showed that sodium, zinc, and nickel were also detected as dominant elements. Initial tests also showed the energy content of the biomass at 15.80 MJ/kg, and that of biochar was measured as 24.51 MJ/kg.
- Algae cultivation
- Algae conversion
Benefits and Advantages
- Environmentally friendly
- Reduces costs of algae cultivation
- Recycled nutrients are effective for growing algae
- Reduces nutrient consumption